cytology – Lablogatory

Thyroid Tales (First Edition)

I’ve found that our cytologists have a love-hate relationship with thyroids. Pathologists do too. Or it could be that we see so many goiters (50%) and follicular lesions or atypia of undetermined significance (35%) that the rare papillary thyroid carcinoma is a gem in our eyes. Minimally-invasive thyroid FNAs are instrumental in the management of thyroid nodules. It’s important to note that due to lack of architecture and assessment of capsular invasion, cytologic diagnoses may be limited, and prior to referring the patient for a potentially unnecessary surgery, various molecular tests can be utilized. The ongoing evolution of molecular testing on thyroid FNAs help classify indeterminate and suspicious cytology diagnoses (Bethesda Categories III and IV), examining the risk of malignancy or detecting the presence of genetic alterations, which help guide surgical intervention versus surveillance. This post (the first edition) features a series of our classic Bethesda Category VI specimens, which bypassed the need for risk classification and defaulted in surgical intervention based on guidelines at the time of diagnosis. It is worth mentioning that many of these cases occurred prior to the implementation of the Thyroid Imaging Reporting and Data System (TI-RADS), so to preserve the accuracy of patient history, a TI-RADS score will not be assumed.

Case 1

Okay, I know I said Bethesda VI, but let’s kick this series off with a Bethesda Category IV case. Thankfully, the patient decided to undergo a partial thyroidectomy, yielding a beautiful tissue follow-up. A 59-year-old male with newly diagnosed melanoma of the neck underwent imaging for staging purposes. A left thyroid nodule was identified measuring 3.0 centimeters. The patient presented for an ultrasound-guided fine needle aspiration.

Images 1-3: Thyroid, Left Lobe, FNA 1: DQ-stained smear; 2: Pap-stained smear; 3. H&E Cell Block section (400X).

Abundant oncocytic Hürthle cells, some with mild atypia, were identified, suggestive of Hürthle cell neoplasm (Images 1-3). With a lack of lymphocytes, we did not feel comfortable suggesting Hashimoto’s (lymphocytic) thyroiditis. Immunostains performed on cell block sections show the tumor cells are positive for TTF-1, focally positive for thyroglobulin and AE1/AE3 (rare), and negative for calcitonin. The morphology and immunohistochemical profile support the above diagnosis.

The patient underwent a left lobectomy and isthmusectomy. Pathology showed a 3.2 cm Hürthle cell carcinoma (Images 4-5) in the left lobe of the thyroid (encapsulated with a foci of capsular invasion without vascular invasion) as well as a 0.3 cm micropapillary carcinoma. Since Hürthle cell carcinoma does not typically concentrate radioiodine, the patient would not be responsive to treatment with radioactive iodine. Therefore, there would be less benefit derived from treating the smaller right lobed nodules (which don’t meet biopsy criteria) from remnant ablation. The patient had a clinically limited stage thyroid cancer. The patient is monitored with neck ultrasounds rather than serum thyroglobulin testing (due to the remaining right lobe).

Images 4-5: Thyroid, Left Lobe with Isthmus, Excision: H&E section (600X).

Cytology diagnosis: Hürthle cell neoplasm.

Pathology diagnosis: Hürthle cell carcinoma.

Case 2

A 53-year-old female with no prior history presented with fatigue and a self-palpated right thyroid nodule and normal thyroid function tests. She reported an extensive family history of hypothyroidism. On thyroid ultrasound, the right upper pole thyroid nodule measured 2.0 x 2.0 x 1.8 cm and was mostly solid and hypoechoic with microcalcifications. Pre-intervention serum calcitonin measured 1634 pg/mL. The patient underwent an FNA of the thyroid nodule and the smears are depicted below.

Images 6-7: Thyroid, Right Lobe, Upper Pole, FNA: 6: DQ-stained smear; 7: Pap-stained smear.

Cells appear plasmacytoid and appear both isolated and in clusters (Image 6). The nuclei are eccentrically placed, and the chromatin has a salt and pepper appearance akin to a neuroendocrine tumor (Image 7-8). Also identified were pink granules and intranuclear pseudoinclusions (Images 6-7). We performed immunohistochemical stains on paraffin sections of the cell block. Tumor cells show positive staining for calcitonin, chromogranin, mCEA, and TTF-1, while negative staining for thyroglobulin and CD45.

Following the diagnosis, the patient had a CT scan for staging purposes. Multiple lymph nodes in the right cervical chain were identified. the patient at a clinical stage IVA diagnosis. In the interim, the patient had a total thyroidectomy which revealed medullary thyroid carcinoma of the right lobe measuring 2.2 cm, a micropapillary carcinoma of the left lobe measuring 0.1 cm (Image 8). Lymphovascular invasion was not identified, the inked surgical resection margins are free of carcinoma, and metastatic medullary carcinoma was identified in 6 of the 77 lymph nodes removed during the central compartment lymph node dissection, and bilateral cervical lymphadenectomies. The calcitonin level dropped to 23 pg/mL postoperatively. Genetic testing was performed to assess for Multiple Endocrine Neoplasia Type 2 (MEN2), and although her result was indeterminate, a RET mutation was not identified.

Image 8: Thyroid, Excision: H&E section (600X).

Case 3

A 67-year-old male with no pertinent medical history presented to the endocrinology clinic after his primary care physician identified a large lump in the patient’s neck. A 7.0 cm hypoechoic right thyroid mass with macrocalcifications was noted on ultrasound imaging. The patient was referred to diagnostic imaging for a thyroid FNA. The smears and cell block section are depicted below. While the papillary formation of Image 9 is not evident on the pap-stained slide (Image 10), the nuclear grooves and pseudoinclusions along with irregular nuclear membranes and powdery chromatin are highlighted. A separate needle pass was collected for molecular testing, which revealed a BRAF V600E mutation in the tumor cells.

Images 9-11: Thyroid, Right Lobe, FNA 9: DQ-stained smear; 10: Pap-stained smear; 11. H&E Cell Block section (600X).

Two weeks after the FNA diagnosis, the patient was scheduled for a partial thyroidectomy of the right lobe. While 60% of the mass demonstrated well-differentiated papillary thyroid carcinoma (Image 12), 40% of the tumor contained poorly differentiated thyroid carcinoma with squamous features (Image 13). No sarcomatous components or giant tumor cells were identified. Carcinoma with squamous features invaded into the surrounding tissue, strap muscle, thymus, and right paratracheal lymph node. Interestingly, the right-sided levels 3 and 4 lymph nodes contained predominantly well-differentiated papillary thyroid carcinoma with rare foci of poorly differentiated thyroid carcinoma with squamous differentiation.

Images 12-13: Thyroid, Right Lobe, Excision: H&E section (600X).

Five months after the excision, the patient developed a left-sided pleural effusion. A diagnostic thoracentesis was performed and metastatic thyroid carcinoma was identified. Immunostains performed on the cell block slides with adequate controls show that the tumor cells are positive for PAX8, and negative for TTF-1, and thyroglobulin. The findings support the diagnosis. While patients with papillary thyroid carcinoma tend to have better disease-free survival rates, the poorly differentiated tumor was difficult to control and eventually resulted in widespread metastasis.

Cytology diagnosis: Papillary thyroid carcinoma.

Pathology diagnosis: Poorly differentiated thyroid carcinoma with squamous features in a background of well-differentiated papillary thyroid carcinoma.

Case 4

A 73-year-old female presented with a rapidly growing and painful thyroid mass that measured 8 cm on imaging. Originating from the right lobe, multiple needle passes targeted various areas of the mass via ultrasound-guidance. The smears and cell block section are presented below. Smears (Images 14-15) feature pleomorphic nuclei in a background of inflammation and necrosis. The cell block section (Image 16) demonstrates increased mitotic figures and neutrophils.

Images 14-16: Thyroid, Right Lobe, FNA: 14: DQ-stained smear; 15: Pap-stained smear; 16. H&E Cell Block section (600X).

We performed immunocytochemical stains on paraffin sections of the cell block. Tumor cells how positive staining for p53, focal staining for cyclin D1, and negative staining for AE1/AE3, thyroglobulin, and BCL-2. Rare tumor cells show staining for TTF-1. The proliferation index by Ki-67 immunostaining is approximately 70%.

While not a standard procedure for thyroid specimens, core biopsies (Image 17) were also obtained from this mass.

Molecular testing on the core biopsy sample identified a high mutation burden, with the tissue harboring both TP53-inactivating and TERT promoter mutations. Imaging demonstrated widespread metastasis, and this patient did not survive the extensiveness of her disease.

Cytology Diagnosis: Undifferentiated (anaplastic) thyroid carcinoma.

Pathology Diagnosis: High-grade carcinoma consistent with anaplastic carcinoma (interchangeable diagnoses).

That’s enough for our classic thyroid cases. Stay tuned for the second edition featuring thyroid FNAs with unsuspecting findings!

-Taryn Waraksa-Deutsch, MS, SCT(ASCP)^CM, CT(IAC), has worked as a cytotechnologist at Fox Chase Cancer Center, in Philadelphia, Pennsylvania, since earning her master’s degree from Thomas Jefferson University in 2014. She is an ASCP board-certified Specialist in Cytotechnology with an additional certification by the International Academy of Cytology (IAC). She is also a 2020 ASCP 40 Under Forty Honoree.

A Series of Infectious Events

Working in a cancer center, our cytologists are well-versed in cancer morphology being able to diagnosis primary malignancies, distant metastases, and even combined metastatic disease in the same lymph node. What we don’t see as often as community hospitals are infectious diseases. However, we do have many immunocompromised patients at our institution, so the rare opportunistic infection does occur. And boy, do we get excited to pass the case around! Please find a series of infectious events embedded within this post. And unfortunately, we do not live in an area where coccidiomycosis is endemic, so beyond school, we haven’t had the pleasure of identifying those in our daily work.

Case 1. Lung, Bilateral, BAL (Bronchoalveolar Lavage)

A 73-year-old male patient was admitted to the ICU with pneumonia. The pulmonologist performed a bilateral bronchoalveolar lavage (BAL) to rule out pneumocystis pneumonia. We prepared a pap-stained smear, two cytospins, a SurePath liquid based prep, and a cell block. Two additional cytospins were sent to histology for GMS staining. While no malignant cells were identified, fragments of squamous epithelium with acute inflammation and necrosis were present. Multiple viral inclusions were identified, appearing as ground glass within the nuclei. (Image 1). These cells present with classic 3 M features: molding, multinucleation, & margination of chromatin. The cell block also highlights viral inclusions, but demonstrates pseudohyphae and spores associated with surrounding squamous cells as well (Image 2).

Images 1-2. Lung, Bilateral, BAL. 1: SurePath LBP; 2: H&E Cell Block section (400X).

Diagnosis: Herpes Simplex Virus (HSV) and Candida.

Case 2. Lung, Left Lower Lobe, CT-guided FNA

A 72-year old male with stage IIA squamous cell carcinoma underwent a VATS right upper lobectomy and mediastinal lymph node dissection. He completed adjuvant carboplatin/gemcitabine therapy. On a surveillance CT scan, the treated area demonstrated progression as well as multiple bilateral lung nodules. To determine whether the new left lower lobe superior segment lung nodule was a metastasis or new primary, a CT-guided biopsy was performed. The smears and cell block sections were negative for malignancy but demonstrated inflammatory cells and necrotic debris, consistent with a necrotizing inflammatory process (Images 3-5). A separate pass was sent for microbiological cultures to correlate our findings. The following day, Kinyoun and GMS stains were performed on paraffin-embedded sections of the cell block. No fungal organisms were identified on GMS, but acid-fast bacilli were noted by the cytologist on the Kinyoun-stained section (Image 6).

Images 3-6. Lung, Left Lower Lobe, CT-guided FNA. 3: DQ-stained smear; 4: Pap-stained smear; 5: H&E section (100x); 6: Kinyoun stain (600x).

Diagnosis: Acid-fast bacilli (AFB), consistent with Mycobacterium Avium Complex. Isolated and confirmed by microbiology.

Case 3. Lung, Right Upper Lobe, CT-guided FNA

A 58-year-old male presented with multiple lung nodules and a brain mass. We reviewed the brain mass excision from an outside institution and agreed with the original diagnosis of anaplastic oligodendroglioma, WHO grade III with a Ki-67 proliferation index that approached 20%. EGFR was not amplified (ratio 1.2), but 1p/q19 co-deletions were noted in greater than 75% of tumor cells. To rule out primary versus metastatic disease, the patient had a CT scan-guided biopsy of right upper lobe lung mass. No malignant cells were identified in the sample; however, necrotic debris and abundant fungal hyphae were noted (Images 7-9). A portion of the sample was sent to Microbiology for culture. The following day, a GMS and PAS stains were performed on paraffin-embedded sections of the cell block which demonstrated the same fungal hyphae seen in the smears and cell block preparations (Images 10 & 11).

Images 7-11. Lung, Right Upper Lobe, CT-guided FNA. 7: DQ-stained smear; 8: Pap-stained smear; 9: H&E section (400x); 10: GMS stain (400x); 11: PAS stain (400x).

Diagnosis: Abundant fungal hyphae, consistent with Aspergillus

Case 4. Left Hilum, EBUS-FNA

A 20-year-old female patient presented with patches, pain, and inflammation on her legs, and she was diagnosed with erythema nodosum. When her swelling and pain worsened, a chest X-ray demonstrated a left hilar mass, and a subsequent CT demonstrated the mass to be encircling the left superior pulmonary artery and obstructing the pulmonary vein along with multiple peribronchial ground-glass opacities and hilar lymphadenopathy. The concern from the referring physician was thymoma versus lymphoma given her age and clinical presentation. The patient underwent an endobronchial ultrasound to assess the hilar mass and lymphadenopathy. The lymph node aspirates appeared benign, with flow cytometry supporting the cytologic diagnosis. On the left hilum FNA, there were aggregates of lymphocytes, plasma cells, and epithelioid histiocytes with caseating necrosis and fibrosis (Image 12-14). Kinyoun, PAS, and GMS stains were performed on paraffin-embedded sections of the cell block. No acid-fast bacilli were identified. Fungal organisms in the form of budding yeast were noted on GMS (Image 15) and PAS stain. The patient was prescribed a 12-week course of antifungal medication.

Images 12-15. Lung, Left Hilum, EBUS-FNA. 12: DQ-stained smear; 13: Pap-stained smear; 14: H&E section (400x); 15: GMS stain (400x)

Diagnosis: Necrotizing inflammation with fungal organisms, suggestive of Histoplasmosis.

Case 5. Lung, Right Middle Lobe, BAL (Bronchoalveolar Lavage)

A 44-year-old male patient with uncontrolled Type II diabetes and hypertension presented to pulmonary after imaging demonstrated diffuse mediastinal and hilar lymphadenopathy. The differential diagnosis was sarcoidosis versus a lymphoproliferative process. An endobronchial ultrasound was performed to evaluate the lymph nodes, all of which came back as reactive. A BAL was performed and sent for cell count, cytology, flow cytometry, and microbiology. Flow cytometry analysis demonstrated a reversed CD4:CD8 ratio, and upon further testing, the patient was determined to have HIV. Eosinophilic froth or casts were identified on the cytopreparations of the BAL (Images 16). GMS and PAS stains were performed with adequate controls, and the PAS was negative for other fungal organisms while the GMS demonstrate positive staining for what we in cytology refer to as cups or crushed ping pong balls (Image 17). He was treated with Bactrim.

Images 16-17. Lung, Right Middle Lobe, BAL. 16: Pap-stained cytospin; 17: GMS stain (600x)

Diagnosis: No malignant cells identified. Positive for Pneumocystis jirovecii.

Case 6. Lung, Right Lower Lobe, CT-guided FNA

A 68-year-old male patient with a history of a renal transplant presented with an endobronchial mass in the left lower lobe that was biopsied and diagnosed as adenocarcinoma at an outside institution. We reviewed the slides in-house and determined the original tumor to be a mucoepidermoid carcinoma. After an unsuccessful staging procedure, a mediastinoscopy was performed, and the mediastinal lymph nodes showed hyalinizing non-necrotizing granulomata, suggesting underlying sarcoidosis. No microorganisms were identified with AFB, GMS, or PAS stains. The patient did not receive adjuvant therapy following the resection of his endobronchial tumor. Seven years later, he presented to the ER for syncope and 30 lbs. weight loss in 5 months. A CT scan was performed demonstrating a thick-walled cavitary lung mass in the right lower lobe. The patient was referred to radiology for a CT-guided FNA of the RLL mass. Fibrous tissue and abundant microorganisms with a polysaccharide capsule were identified on both FNA and core biopsy (Images 18-20). The PAS, GMS, Mucicarmine (Image 21), and Fontana Masson special stains were performed on cell block sections, with proper controls, highlighting abundant microorganisms. The patient was prescribed an antifungal for his cryptococcoma (cryptococcal lung abscess).

Images 18-21. Lung, Right Lower Lobe, CT-guided FNA. 18: DQ-stained smear; 19: Pap-stained smear; 20: H&E section (600x); 21: Mucicarmine stain (400x)

Diagnosis: No malignant cells identified. Abundant microorganisms, morphologically consistent with Cryptococcus species.

If you enjoyed this special series, look out for more in the future! And feel free to recommend or request interesting cases!

Histio Makes History

An 81 year old female presented to the head and neck clinic after being diagnosed with cutaneous T cell lymphoma of the posterior mid-parietal scalp at an outside institution. She was initially treated with Brentuximab every three weeks but developed significant toxicities. The patient’s previous “T cell lymphoma” material was reviewed at our institution and the immunophenotypic report described the neoplastic cells as being positive for CD45, CD2, CD4, BCL6+, CD3 (subset), and CD123 (scattered), while negative for CD7, CD8, CD20, CD30, CD56, EBER ISH, PAX5, and lysozyme. Immunohistochemical slides were not provided for review. Flow cytometric analysis determined that there was no immunophenotypic evidence of a clonal T cell population in the patient’s peripheral blood.

A second scalp biopsy was performed at another outside institution, and the findings were similar to the parietal scalp; however, there were atypical pleomorphic cells which displayed irregular contours, hyperchromasia, and multiple nucleoli. The atypical cells were predominantly positive for CD4 and diffuse positivity for CD1a. These same pleomorphic cells were negative for CD3, CD8, CD20, CD30, ALK1, BCL6, CD56, EBER, AE1/AE3, SOX10, Desmin, PAX5, MUM1, CD5, and Cam 5.2.

The smears contained large, highly pleomorphic cells with irregular, elongated, and multilobated nuclei, frequent nuclear grooves and folds, fine chromatin, prominent nucleoli, and variable amounts of pale, eosinophilic cytoplasm, alt.

The outside tissue block on the original scalp biopsy was requested, and our pathology department performed additional immunostains. The neoplastic cells of interest were positive for CD1a, S100, CD68 (a small subset), and negative for lysozyme, CD21, CD30, and CD3. Ki67 proliferation index was interpreted at approximately 60%. An unstained FFPE tissue section was sent to a reference laboratory, and the neoplastic cells were strongly positive for Langerin.

While the Brentuximab treatment initially appeared to have a positive impact on the overall disease burden, the PET CT following 3 cycles showed a mixed response, including resolution of cervical lymphadenopathy and identification of multiple new lung nodules and bulky mediastinal lymphadenopathy. Between that and numerous reported toxicities, the treatment protocol was discontinued. The patient was then referred to radiology for a CT-scan guided right lower lobe lung biopsy measuring 2.2 x 1.3 centimeters with an SUV or 29.6.

In the CT Scan suite, we received multiple FNA passes from the interventional radiologist and made air-dried and alcohol-fixed smears, rinsing the residual needle material into a tube of balanced salt solution for a cell block preparation. We determined our specimen was adequate for scant tumor cells, as depicted on the Diff-Quik smears below.

Images 1-2. Lung, right lower lob, CT-guided FNA. Diff-Quik stained smears.

In comparison to the material from the second scalp biopsy, the cells from the lung biopsy appeared identical. Our Pap-stained smears and H&E cell block sections also demonstrated the highly pleomorphic cells described above.

Images 3-6. Lung, Right Lower Lobe, CT-guided FNA. 3-4: Pap-stained smears, 5-6: H&E sections (5: 100x, 6: 400x).

Immunostains performed on the cell block slides with adequate controls show that the tumor cells are positive for CD1a, CD4, partially positive for CD45 and S100, negative for AE1/3, TTF-1, and p40.

Images 7-8. Lung, Right Lower Lobe, CT-guided FNA. Cell block section immunohistochemistry. 7: CD1a-positive; 8: partially S-100-positive.

Our pathologists felt the cells from the second scalp biopsy and the lung biopsy were representative of a Langerhans cell sarcoma, a form of malignant histiocytosis, rather than a T-cell lymphoma. It is possible that the first scalp biopsy’s diagnosis of T-cell lymphoma was due to sampling error and the pleomorphic cells of interest were missed. The Ki-67 proliferative index of 60% helped to distinguish between Langerhans cell histiocytosis and Langerhans cell sarcoma.

Molecular testing performed on the core biopsy was negative for a BRAF mutation and positive for an NF1 inactivating mutation. The tumor may then be sensitive to mTOR inhibitors and MAPK pathway inhibitors, such as MEK inhibitors. Appeals for a MEK inhibitor were denied by insurance, but fortunately, the tumor also demonstrated high PD-L1 expression at 90%, making this specific patient a candidate for pembrolizumab, which was fully covered by insurance.

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I can’t help but think about the disparities associated with cancer and the inaccessibility of potentially lifesaving or life-prolonging treatments. Sure, there may be viable alternatives, such as this case, but what if we had equal access to cutting edge, personalized therapies? What if the only therapy available was too costly to bear? Just because a cancer might be rare, such as Langerhans cell sarcoma, it doesn’t mean access to a proven effective therapy should also be rare. Even with drug assistance programs, so many patients face the harsh reality of tapping into their life savings to just to save their own life. When we became medical laboratory professionals, we promised to provide timely and accurate for all of our patients. Now, it’s time that pharmaceutical companies and our healthcare system as a whole work together to provide high quality, low-cost, readily accessible and personalized treatment options to every patient. They deserve that chance to overcome or at least manage their cancer.

Tumor on the Brain

Back in my Master’s program at Jefferson, I fondly remember the week we covered central nervous system (CNS) tumors. I was fascinated by the mnemonic tools we would use to identify different CNS tumors, such as “fried eggs” for oligodendrogliomas, perivascular pseudorosettes in ependymomas, and the whorling associated with meningiomas. Fortunately, for our patients, and unfortunately, for our diagnostic curiosity, we rarely see CNS tumors at my institution. Brain lesions resulting from metastatic carcinomas are typically well-identified via imaging and treated appropriately by the surgical, medical, and radiation oncology teams, but cytologists are available to screen cerebrospinal fluids (CSFs) for CNS involvement. For primary CNS tumors, however, we’re left recollecting the core memory of the second semester of our didactic phase. When a metastatic CNS tumor made its way into our lab, our cytology team swooned with excitement. (Yes, I know, but please introduce me to a lab professional who doesn’t embrace their quirks.) A 27-year-old male patient presented to radiation oncology three years after surgical debulking of a brain tumor at an outside institution. The patient, who was referred to radiation oncology at to treat the residual tumor at the original institution, did not follow up and developed an 8 centimeter recurrence a year after the initial resection. At this point, the patient experienced complete vision loss and underwent a biparietal-occipital craniectomy. A repeat brain MRI was performed a year later, and once again, a large enhancing extra-axial mass was identified along with multiple smaller masses also increasing in size. The patient received radiation after worsening difficulty with ambulation. After almost completing the planned fractions of radiation, the patient elected to stop their radiation therapy due to worsening seizures. A left neck mass was identified six months prior, and while the mass had not grown or caused pain, the patient was referred to head and neck surgical oncology for evaluation. Surveillance imaging demonstrated an enlarged left level 5A lymph node, suggestive of metastatic disease. Multiple ultrasound-guided fine needle aspiration biopsies were obtained from the lymph node, and ROSE was performed. The Diff-Quik-stained and concurrent Pap-stained smears demonstrated lesional tissue, although everything from epithelioid histiocytes to spindle cell melanoma to a renal primary were considered as a differential. Based on the location, a salivary gland primary was also a possibility for this case. The streaked cytoplasm and pseudoinclusions in both smears were concerning for a metastasis of the patient’s primary CNS tumor, but we were still hesitating to make the call.

Images 1-4. Lymph Node, Neck, Left, Level 5A, US-guided FNA. 1-2: Diff-Quik-stained smears, 3-4: Pap-stained smears.

The following morning, the H&E-stained FFPE cell block sections demonstrated the characteristic whorls expected for the patient’s primary, although the idea of metastasis was uncanny.

Images 5-6. Lymph Node, Neck, Left, Level 5A, US-guided FNA. H&E sections (6: 100x, 7: 400x).

We then used immunohistochemical studies to confirm our morphologic diagnosis. Immunostains performed on the cell block slides with adequate controls show that the tumor cells are positive for vimentin and PR (focal), while negative for AE1/AE3, EMA, CK7, CK20, TTF-1, Napsin A, p40, Pax8, synaptophysin, and S-100. The Ki-67 proliferation index fell at 18%, which is consistent with intermediate aggressive disease in a WHO Grade 2 atypical meningioma.

Images 7-8. Lymph Node, Neck, Left, Level 5A, US-guided FNA. Cell block section immunohistochemistry. 7: Vimentin-positive; 8: focally PR-positive.

The patient had next gen sequencing performed on his tissue, which demonstrated an NF-2 mutation, indicating he may benefit from MTOR inhibitors, but he elected not to pursue systemic therapy.

Where meningiomas account for 36% of primary brain tumors, atypical meningiomas comprise only 5-15% of all meningiomas (Cai et al., 202. Extracranial metastasis of atypical meningioma is a rare event, with only a few cases documented in the literature. While meningioma metastases are uncommon, a thorough collaboration between clinical impression and pathologic interpretation is necessary to ensure the possibility is not entirely excluded.

References

Cai C., Kresak J.L., Yachnis A.T. (2021) Atypical meningioma. Pathology Outlines. Retrieved October 11th, 2022, from https://www.pathologyoutlines.com/topic/cnstumoratypicalmeningioma.html.

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Triaging Times

As a clinical instructor and lead cytologist at my institution, I like to remind our newer cytologists and cytology students of the importance of being prepared for FNA biopsies so they develop good habits or best practices as they become more experienced. This level of preparation helps to create a culture of ongoing learning and improvement, which is necessary for the laboratory. In my experience, I’ve met some cytologists who prefer to go into a case blind, with the mindset that knowing the patient’s clinical history in advance muddies their knowledge, skills, and abilities, limiting their mindset by excluding the possibility of other diagnoses. While diving into the unknown might seem exciting, it is also a hindrance and could result in errors, especially when the clinical history helps us triage the patient’s sample. For example, knowing that the patient has a history of lymphoma or that the presentation state includes bulky lymphadenopathy prompts us to collect additional needle passes to send for flow cytometry analysis. Another concern is not knowing whether the patient has a history of breast, gastric, or esophageal cancer, and consequently processing the specimen routinely, which may result in an extended cold ischemic time. This delay in fixation along with insufficient formalin fixation can yield false negatives on ER/PR IHC in breast cancers and HER2 FISH in breast, gastric, and esophageal cancers, which could restrict the use of hormone therapies, such as tamoxifen and aromatase inhibitors for hormone receptor-positive (HR+) cancers, or trastuzumab for HER2+ cancers. I cannot overemphasize the importance of familiarizing yourself with clinical history and communicating case specifics while you act as a mediator between clinician and pathologist.

Whether the clinical history impacts the pre-analytical phase, such as specimen collection (limiting cold ischemic time or collecting additional needle passes for ancillary studies) or the analytical phase, as such processing (formalin fixation) and diagnosis (selecting an appropriate immunoprofile), we must remain vigilant and proactive in laboratory medicine. In this case, knowing the patient’s clinical history was of the utmost significance as it helped to reduce the number of immunostains and ancillary studies necessary to make the diagnosis. Using morphologic criteria in tandem with the patient’s clinical history narrowed the differential diagnoses to just two possible types of cancer, presented below.

A 59 year old male patient presented to the emergency room after an automobile accident. On imaging, the X-ray and CT scan identified a left humerus mass and fracture, and bloodwork was performed. His medical record was sparse and uneventful with no recent visits or encounters. To build a more comprehensive wellness profile and prepare for surgery, he was also offered a one-time screening for Hepatitis C, as an adult who was born between 1945 and 1965.

The left humerus mass was biopsied via CT-scan guidance and two passes were obtained. The Diff-Quik stained smears demonstrate large polygonal cells, some with abundant, granular cytoplasm and some isolated cells with naked nuclei. Vessels also appear to traverse some of the cell groups.

Images 1-2: Bone, Humerus, Left, CT-guided FNA. Diff-Quik-stained smears.

The Pap-stained smears also demonstrate polygonal cells with granular cytoplasm, nuclei with coarse chromatin, and prominent nucleoli. An interesting feature frequently identified in this case is the intranuclear inclusions, and in hindsight, a focus on these may have further reduced the number of immunostains performed.

Images 3-5: Bone, Humerus, Left, CT-guided FNA. Pap-stained smears.

The H&E-stained cell block sections show trabeculae with endothelial wrapping around the cell cords. While renal cell carcinoma was listed as a differential diagnosis due to its telltale oncocytic cytoplasm and vascularity, hepatocellular carcinoma was favored.

Images 6-7: Bone, Humerus, Left, CT-guided FNA. H&E sections (6: 100x, 7: 400x).

Immunostains were performed using proper positive and negative controls on the cell block sections, and the tumor cells show positive staining for Arginase, cam5.2, and Hepar1, while negative staining for CK7 and PAX8 (not shown).

Images 8-10: Bone, Humerus, Left, CT-guided FNA. Cell block section immunohistochemistry. 8: Arginase-positive; 9: cam5.2-positive; 10: Hepar1-positive.

Fortunately, before ordering immunostains, both our cytologist and pathologist working on the case peered into the patient’s medical record and noticed that he had recent bloodwork which demonstrated a positive Hepatitis C screening. This diagnosis was as recent as the identification of his humerus mass. Had it not been for his car accident, I can’t imagine how long he would have gone undiagnosed for both hepatitis and metastatic hepatocellular carcinoma. Incidental findings save lives, folks.

Granted, in settings of unknown primaries with widespread metastatic disease, such as carcinomatosis, an extensive workup is almost always inevitable. Narrowing down possible etiology based on information such as gender, age, and environmental or occupational exposure can help, but that doesn’t always yield a definitive answer as time- or cost-effectively as possible. In this case, that one clue of untreated Hepatitis C was all the cytopathology team needed. A rarity, sure, but as we are asked to do more personalized tests with less material, think of the patient’s specimen as a puzzle and keep your eye out for a clue both under the microscope and behind the computer. You never know what you might find that reduces errors and unnecessary testing while efficiently leading to a definitive diagnosis.

BOGO: Biopsy One, Get One Free

I’ve mentioned before how important it is to know clinical history before attending a biopsy, and I cannot stress this point enough. As the first line of screening, the intermediary between clinician and pathologist, the role of the cytologist is to prepare, assess, and convey. In a cancer center, we have three main populations: the patients with the unknown primary, the patients with the suspected primary, and the patients with the suspected metastasis. In the event of a suspected metastasis, we’ll review previous relevant pathology material if we have it onsite. Unless the clinician is requesting additional prognostic markers, the review process helps us eliminate the unnecessary repetition of immunostains (IHC) by confirming that the current material is morphologically consistent with the prior material. Sometimes we still perform old-school cytology without a plethora of ancillary studies. HA!

Most of the endobronchial ultrasound (EBUS) procedures performed at our institution are for lung cancer staging or differentiation between a lung cancer metastasis and an extra-pulmonary metastasis. Not that we don’t see the occasional sarcoid- or anthracosis-related process from time to time, but our most common indication is cancer. For an 88-year-old male patient with multiple lung nodules and both mediastinal and hilar lymphadenopathy, confirmation of metastasis was the main objective of the EBUS procedure. The patient’s pertinent medical history includes former tobacco use, squamous cell carcinoma of the lung (diagnosed percutaneously in 2022), clear cell renal cell carcinoma (s/p partial nephrectomy in 2020), prostate cancer (radiated in 2007), melanoma (excised in 2001), and cutaneous squamous cell and basal cell carcinoma (also previously excised in 2002 and 2008). With an extensive cancer history, the lung nodules and thoracic nodes could be any of them, although metastatic squamous cell carcinoma of the lung was clinically favored. My awesome cytologist colleague, Kelly, attended the EBUS procedure. The Rapid Onsite Evaluation (ROSE) was a clear-cut “adequate for diagnostic material,” and the attending pathologist added “tumor cells present.” The following morning, Kelly stopped by my desk to ask my opinion of the 12R (right hilar) lymph node she was screening. She said, “look at my dots. Do these look like the same cells to you? Or are they different? Because I feel like they’re different.” Before putting the slide on my scope, I asked, “so… like a combined adenosquamous? Or a small cell component?” She replied, “not small cell. Something… I don’t know, but they look different. The patient was recently diagnosed with lung cancer and has a history of renal cell.” I fixated on the H&E cell block slides (Images 1-3) before perusing the Diff-Quik and Papanicolaou-stained slides (Images 4-5). “Uhm… Why are there two different types of tumor cells here?! The cytoplasm here is so… vacuolated, but it’s not quite like lung adeno, and the other group… even the n/c (nuclear-to-cytoplasmic) ratio is different. What is this?” Kelly replied, “okay, so there are definitely two different types of tumor here.” I looked up, “It has to be. Absolutely, yes.”

Images 1-4. Lymph node, 12R, EBUS-guided FNA. 1-3: H&E cell block sections 1, 100x; 2, 400x; 3, 100x. 4: Diff-Quik stained smear.

Image 5. Lymph Node, 12R, EBUS-guided FNA. Pap-stained smear.

Kelly entered her diagnosis into our laboratory information system and brought the case over to the pathologist on cytology service for the day. She explained her thought process, and the pathologist also questioned if it was a combined process, such as a lung adenosquamous and maybe the original lung biopsy only sampled the squamous component. With the most recent clinical history of both lung squamous cell carcinoma and clear cell renal cell carcinoma, an IHC panel was appropriately selected. Later that afternoon, the pathologist exclaimed, “IT’S BOTH! IT’S SQUAMOUS AND RCC!” The clusters of squamous cell carcinoma did not stain for PAX8 (a renal cell carcinoma marker) (Image 6), and the same cluster stained positive for p40 (a squamous cell carcinoma marker) (Image 7). Within the same level of the cell block, the cluster of cells that appeared morphologically different than squamous cluster stained positive for PAX8 (Image 8) and negative for p40 (Image 9), confirming a renal cell carcinoma component. A small focus of p40-positive cells was present next to the p40-negative renal cell carcinoma (Image 9), further demonstrating mixed histology. This finding was shared with other pathologists, and the results were immediately called to the pulmonologist as this was a critical finding. Sometimes we encounter a partially involved node where the tumor cells are intermixed with lymphocytes, sometimes the lymph node yields more tumor than the primary site, and sometimes, albeit rarely, we encounter a lymph node infiltrated by two different carcinomas.

Images 6-9. Lymph Node, 12R, EBUS-guided FNA. Cell block section immunocytochemistry. Squamous cell carcinoma cluster – 6: PAX8-negative; 7: p40-positive. Renal cell carcinoma cluster – 8: PAX8-positive, 9: p40-negative (with small focus of p40-positive squamous cell carcinoma).

Due to the patient’s bulky disease and PD-L1 expression of 30%, the medical oncologists primary aim was to treat the squamous cell carcinoma first and follow up renal cell carcinoma therapy second. After the first few cycles of treatment, the lung nodules have decreased in size, but the thoracic nodes remain unchanged. Once the squamous cell carcinoma is controlled or demonstrates a more significant response, immunotherapy may be added to target both, with a tyrosine kinase inhibitor directed at renal cell carcinoma metastases in the event of progression.

While We Are Young

Preface: I wish we lived in a world where cancer did not exist. While I do not foresee that being a reality in my lifetime, I hope I can witness a milestone in oncology when the development of safe and effective therapies surpasses the rate of metastasis. I hope to see the day when instead of being five steps behind cancer, we gain our footing and come out at least one step ahead. We can’t be that far away, right? When I see a patient who is younger than me or around my age, I can’t help but ask myself, “why they have to go through this? Why do they have to be diagnosed with cancer?” Now, they have to choose whether or not to undergo fertility sparing treatment in addition to making a shared decision regarding cytotoxic therapy and radiation. They’re just beginning their life, their career, their family; they’re finally building their story, and it’s interrupted by cancer. Rather than a partner or friend, I see many younger patients present to our clinic with a parent. Imagine how that feels to be a parent – knowing your child was just diagnosed with a terminal disease. How does one cope with that? No parent should have to endure the pain and emotional suffering of losing their child to cancer, let alone anything. We’re meant to outlive our parents, we’re meant to enjoy a full and healthy life, and this case tore right through me.

The patient, a 28 year old male, first presented to an out-of-state health system after managing intermittent right hip discomfort with NSAIDs and ice for three years. When the pain worsened, he went to an urgent care toward the end of 2018, but his X-rays were negative. After his pain became unbearable six months later, he had an MRI which demonstrated a proximal femur lesion with hip and sacral involvement. The femoral lesion biopsied via FNA, and the patient underwent 6 cycles of induction chemotherapy prior to resection. The patient’s PET scan showed improvement, and the 10.5 cm hip mass was resected demonstrating fibrosis and no residual disease. Additional chemotherapy was prescribed for consolidation followed by radiation to the sacral lesions. Seven months after no evidence of disease, a surveillance PET scan demonstrated abundant bone lesions in the arms, ribs, and pelvis. A new relapse chemotherapy regimen was prescribed for refractory disease, but within cycle 2, new calvarial lesions were identified. By the beginning of 2021, the patient underwent stem cell harvesting followed by myeloablative/salvage chemotherapy and an autologous stem cell transplant. Soon after he transferred his care to our institution a few months later, the patient underwent a successful stem cell transplant and remained stable for three months post-transplant. The patient began experiencing severe pain which prompted earlier surveillance imaging, and both PET scan and MRI demonstrated extensive disease progression. To improve comfort and confirm etiology, a right thoracentesis was performed, and 1,200 mL’s of bloody fluid was sent to our cytology lab for analysis. The findings are presented below.

At our institution, we use one or two drops of fresh fluid to make a cytospin for triage purposes. We examine the air-dried, Diff-Quik-stained cytospin to determine whether or not the cells are likely to contaminate our routine preparations, and if the cells are overtly malignant, the remaining cytopreparations need to be stained in our known-positive fluid set-up. In this case, the specimen was deemed routine despite the few clusters of cells that do not resemble the predominating mesothelial cells. The tightly clustered group in Image 1 has small, round nuclei; fine chromatin; scant, blue cytoplasm; and atypical mitoses.

Image 1. Pleural fluid, right. DQ-stained cytospin.

The pap-stained smears and liquid-based SurePath preparation were then screened and the cells of interest highlighted below.

Images 2-4. Pleural fluid, right. 2-3, Pap-stained smears; 4, SurePath liquid-based prep.

Similar to the Diff-Quik preparation, the small, round cells of interest are forming tight clusters with each cell approximately twice the size of a normal lymphocyte (Image 3). The nuclei are fairly uniform with fine chromatin, relatively small, inconspicuous nucleoli, and scant cytoplasm (Image 2 & 3). The clustering, while not characteristic of this type of tumor, is most likely artifact due to reactivity of being suspended in fluid. What is not pictured in this specimen is the classic Homer-Wright pseudorosettes.

The cell block sections are consistent with the previous cytopreparations, demonstrating a two-cell population. Small, round blue cells (some forming distorted rosettes) in a background of benign-appearing mesothelial cells.

Images 5-6: pleural fluid, right, H&E cell block sections. 5, 100x; 6, 400x.

This pleural fluid was diagnosed as positive for malignant cells: consistent with the patient’s known Ewing sarcoma. While immunostains were not necessary for this stage IV diagnosis, the cell block sections are expected to stain positive for CD99 (membranous), vimentin, and FLI1 (as an EWSR1 [22q12] break apart rearrangement (83%) was detected in this patient). A few days after this fluid was signed out, the patient passed away, and his family is now undergoing genetic testing.

-Taryn Waraksa, MS, SCT(ASCP)^CM, CT(IAC), has worked as a cytotechnologist at Fox Chase Cancer Center, in Philadelphia, Pennsylvania, since earning her master’s degree from Thomas Jefferson University in 2014. She is an ASCP board-certified Specialist in Cytotechnology with an additional certification by the International Academy of Cytology (IAC). She is also a 2020 ASCP 40 Under Forty Honoree.

Peritoneal Problems

A 74 year old male patient with an extensive cardiac history initially presented to the ER with black stool, warranting a CT scan, upper endoscopy, and colonoscopy, identifying a large, obstructive mass in the colon, smaller, yet unresectable polyps, and subcentimeter liver lesions and lung nodules. The colonic mass was biopsied, consistent with adenocarcinoma; however, the liver lesions were too small to characterize. One month after the onset of symptoms, a right hemicolectomy was performed, and the pathology was signed out as moderately differentiated adenocarcinoma, microsatellite stable, with evidence of lymphovascular and perineural invasion, placing the patient’s stage at IIA (pT3, pN0, cM0). Through shared decision-making, the medical oncologist and patient elected for surveillance due to multiple comorbidities. Forgoing adjuvant therapy, the patient was discharged to physical therapy/rehabilitation. The patient returned for imaging 4 months after his hemicolectomy, demonstrating an enlargement in one of the liver lesions, but then, the patient was lost to follow-up for 20 months.

The patient reestablished care and surveillance imaging, which demonstrated a hypodense liver lesion (in a background of poorly visualized subcentimeter liver lesions), a nonocclusive thrombus in the right portal vein, a heterogenous enhancement of the left portal vein (suggestive of an underlying tumor thrombus), and an 8 cm heterogenous right adrenal mass. Based on the most recent CT scan, the differential diagnoses of the adrenal mass include metastatic disease or a primary adrenal lesion including adrenal cortical carcinoma or pheochromocytoma (for which biochemical analysis should be performed before attempting a biopsy). Extensive peritoneal lymphadenopathy was visualized as well. The area of the right hemicolectomy, however, did not show evidence of recurrence. After biochemical evaluation for metanephrines ruled out a pheochromocytoma, the patient underwent a CT scan-guided adrenal FNA and core biopsy.

The Diff-Quik smear assessed at the time of biopsy revealed a highly cellular specimen, some cells with bare nuclei, enlarged nuclei, and some pseudoglandular structures.

Images 1-2: Adrenal Gland, Right, Fine Needle Aspiration. 1-2: DQ-stained smears

Telepathology confirmed an adequate sample of tumor cells present, and core biopsies were obtained.

The following morning, the pap-stained smears and H&E cell block sections were screened. The cells appeared polygonal with a high N/C ratio and prominent macronucleoli. Cell arrangements formed thickened trabeculae. However, the cytoplasm is more granular than the lipid-rich cytoplasm seen in an adrenal cortical carcinoma. The H&E cell block sections depicted a beautiful trabecular pattern with endothelial cells wrapping the periphery.

Images 3-6: Adrenal Gland, Right, Fine Needle Aspiration. 3-4: Pap-stained smear; 5-6: H&E Cell Block sections.

The preliminary morphology was interpreted as carcinoma, and both cytotechnologist (or cytologist, as we now prefer to be called) and pathologist suggesting features of adrenal cortical carcinoma; however, the IHC markers proved otherwise!

Images 7-9: Adrenal Gland, Right, Fine Needle Aspiration, IHC Cell Block Sections. 7:HepPar1+; 8: Arginase+; 9: pCEA (canalicular pattern)+.

Other differential diagnoses considered renal cell carcinoma and pheochromocytoma (to be safe). The IHC profile ruled out adrenal cortical carcinoma as the cells of interest were negative for inhibin, calretinin, and Melan A. Negative PAX-8, EMA, AE1/AE3, and vimentin staining ruled out renal cell carcinoma, and negative chromogranin, synaptophysin, GATA-3, vimentin, and S100 staining enabled us to safely say that a pheochromocytoma was out of the equation as well. Positive staining for HepPar1, arginase, pCEA (canalicular pattern), and CAM5.2 supported the unlikely diagnosis of metastatic hepatocellular carcinoma (HCC).

This diagnosis placed the patient at Stage IV HCC. It came to light that the patient has a remote history of hepatitis and a high-risk history of drinking, contributing to a poor prognosis. Due to the patient’s condition, they held off on HCV antiviral therapy and decided to observing viral load through regular blood work. The patient and clinician discussed the risks and benefits along with alternatives of systemic therapy, as his multiple comorbidities still pose a significant risk. Immunotherapy was determined to be the best option to delay the progression of his cancer and maintain quality of life.

E(cto)pic Metastasis

A 72 year old female originally presented with lung carcinoid and bilateral renal masses. The patient’s left kidney biopsy demonstrated ectopic thyroid parenchyma by an outside institution. Her thyroid function tests were unremarkable, she had no known previous head and neck radiation, and to the best of her knowledge, there was no family history of thyroid cancer. She underwent FDG PET imaging, which showed increased bilateral uptake in the neck (thyroid and lymph nodes), and an avid right posterior renal mass. Otherwise, her scan was relatively clear. Her left renal mass was resected and demonstrated thyroid parenchyma, but the differential diagnoses included thyroid heterotopia and metastatic well-differentiated thyroid carcinoma.

FNA and core biopsy were then obtained from the right upper quadrant of the kidney. The findings are depicted below.

Images 1-6: Kidney, Right, Fine Needle Aspiration. 1: Pap-stained smear; 2: DQ-stained smear; 3: H&E Cell Block section; 4: TTF-1+; 5: Thyroglobulin +; 6: CK7+.

The FNA was signed out as “Atypical thyroid tissue present.” Immunohistochemical stains demonstrated positive staining for CK7, vimentin (partial), TTF-1, thyroglobulin, and PAX-8 (partial), and negative staining for RCC, Napsin A, synaptophysin, and chromogranin. While these immunostains suggest thyroid-type tissue, morphology was most worrisome for metastatic thyroid carcinoma. The chromatin presented as hypochromatic and powdery, nuclear grooves and pseudoinclusions were present, and the nuclei were enlarged with irregular membranes. However, the scant material present precluded a definitive diagnosis.

Images 7-8: Kidney, Right, Core Biopsy. 7, H&E section 100X; 8, H&E section 400X.

The core biopsy suggested benign-appearing thyroid tissue similar to that seen in the left kidney, however, the surgical pathologist diagnosed the material as metastatic thyroid carcinoma.

A thyroid FNA was obtained from one of the patient’s multiple right-lobed thyroid nodules consistent with TI-RADS category 5 the next day. This was diagnosed as atypia of underdetermined significance due to scant cellularity.

Images 9-10: Thyroid, Right Lobe, Fine Needle Aspiration. 9: DQ-stained smear; 10: Pap-stained smear.

The right renal mass was resected after molecular profiling was performed on the left renal mass tissue. Mutation Detection by Next Generation Sequencing demonstrated a tumor mutation burden of 3.6Muts/Mb and identified mutations in the PRKDC, PTEN, and KRAS genes. Two kidney tumors were identified in the right kidney (one measuring 8.0 cm and the other 4.5 cm), both diagnosed as metastatic thyroid carcinoma with papillary features.

Images 11-12: Kidney, Right, Resection. 11, H&E section 40X; 12, H&E section 400X.

The thyroid was then resected, and pathologic findings were consistent with invasive follicular carcinoma with extensive angioinvasion to 4 or more vessels. While renal metastases are rare, the high affinity for angioinvasion makes the kidney a prime metastasis site due to its vascular-rich tissue. The patient was prescribed a low iodine diet and Thyrogen-stimulated radioiodine ablation to remove any remaining thyroid tissue or micrometastases and enhance the sensitivity of thyroglobulin as a tumor marker for surveillance purposes. While thyroid cancer (papillary and follicular types) is typically considered “the best cancer to have” due its slow growth and low-risk of widespread malignancy, it doesn’t mean that it won’t metastasize, even to a distant organ that you normally wouldn’t suspect. Great caution must be taken to ensure that lumps, bumps, and swallowing issues are addressed at annual physicals to catch a low-risk cancer before it has the opportunity to become an epic metastasis.

By the Book

One of my favorite parts of being a cytotechnologist is the delight of having cytology students rotate through our institution as a practicum site. The pandemic caused a clinical rotation hiatus for the safety of both our staff and students, but thanks to widespread healthcare vaccination, we were able to bring in some fresh minds to experience the variety of interesting cases we enjoy every day. I think what I love most about having students here is reminiscing of when I was in their shoes seven years ago. I remember going into my rotations using nothing but morphologic criteria I memorized from lecture and labs. My clinicals served as a rude awakening that we rarely see any textbook perfect cases. Cancer is like a shape-shifter – one melanoma looks entirely different than another. Two lung squamous cell carcinomas from the right upper lobes from two different patients could look entirely different. The unique variation within and between cancer types is what makes this field so beautifully fascinating. The first time a cytotechnology student shows me a case, tells me their thoughts, works through the criteria, and lists the differentials, I look up and say, “nothing is quite by the book.” How often we fall into a routine of relying on criteria, closing our minds to certain diagnoses because it doesn’t quite look like the clinical impression. When the pathologic and clinical impressions divide, more diagnostic tests are performed, CPT codes fill our billing tab, and we start to panic. “It’s supposed to be adenocarcinoma, so why doesn’t it look like adenocarcinoma?!?

A few weeks ago, the lab received a left pleural fluid from a patient who presented with a history of small cell cervical cancer. I remember learning about this in my first semester of grad school – how rare a finding of small cell carcinoma is, accounting for less than 5% of cervical cancers. It essentially mimics small cell carcinoma of the lung and other neuroendocrine carcinomas, where you should be able to identify the telltale salt-and-pepper chromatin, nuclear molding, scant cytoplasm, loosely cohesive or isolated, necrosis, usually an absence of nucleoli, a high proliferation index with mitotic figures, etc. It’s an aggressive disease to say the least, just like its lung counterpart. When this cancer metastasizes, it takes its same characteristics with it, spreading rapidly without care.

The first step in processing a fluid is to prepare a fresh, air-dried, Diff-Quik-stained cytospin to triage the specimen and decide whether the specimen should be processed routinely or hand-prepped and stained with overtly positive fluids to prevent cross-contamination. There was one cluster identified on the Diff-Quik preparation, but compared to the background of mesothelial and inflammatory cells, the tumor content was insufficient to push it up to hand-processing. The bluish cytoplasm caught my attention as a feature of neuroendocrine tumors AND lymphomas, but the nuclear molding had me favoring neuroendocrine.

Image 1. Pleural fluid, left. DQ-stained cytospin.

That afternoon, I examined the pap-stained smears and SurePath liquid-based preparation, identifying similar cells of interest. However, despite the presence of nuclear molding and scant cytoplasm, the nuclei presented with prominent nucleoli. An interesting feature, to say the least.

Images 2-5. Pleural fluid, left. 2-3, Pap-stained smears (2, lightened to highlight nucleoli); 4-5, Pap-stained SurePath liquid-based preparation.

The following morning, I screened the cell block slides and came across molded groups of cells (appearing as a garden aerial view). Still the prominent nucleoli baffled me, and I thought, “Why doesn’t this look like a classic small cell carcinoma? They clinical history even included known lung mets from the patient’s small cell cervical cancer!”

Images 6 and 7: pleural fluid, left. 6, H&E cell block section 100X; 7, H&E cell block section 400X.

When I sent the case for review by the pathologist, I wrote up a diagnosis of Positive for Malignant Cells; Carcinoma, small cell? Recommend correlation with IHC.” My attending was just as intrigued. She ordered a thorough panel of immunohistochemistry stains based on the morphologic findings.

Images 8-11. Pleural fluid, left. 8, synaptophysin+; 9, CD56+; 10, TTF-1+; 11, BerEP4+.

The tumor cells are positive for synaptophysin, CD56, TTF-1, and BerEP4, focally positive for CK7 and chromogranin (not shown), and negative for calretinin, PAX-8, and p40 (also not shown). The findings support the diagnosis of metastatic high grade carcinoma with neuroendocrine differentiation.

While the stains support a diagnosis of small cell carcinoma, the morphologic diagnosis was mildly questionable. I went back to the patient’s record to see what we may have missed in the clinical history. It turns out the patient initially presented with Stage IB2 HPV+, moderately-differentiated cervical adenocarcinoma in 2020. After completing brachytherapy and one cycle of chemotherapy, but could not tolerate additional treatments due to leukopenia and elevated LFTs. Shortly thereafter the patient complained of abdominal pain and a liver mass and bulky lymphadenopathy were identified on imaging. An FNA of a supraclavicular lymph node confirmed not only metastasis of the patient’s cervical cancer, but discovered a small cell/neuroendocrine transformation. And this is why proper documentation of clinical history is so important to pathologists and laboratory professionals. In one of my earlier posts, I preached that cancer doesn’t discriminate; so why should we? Keeping an open mind is paramount to both succeeding in and enjoying the field of cytopathology. If it looks like a duck, and it walks like a duck, it might actually have transformed into a goose.