Hematopathology and Molecular Diagnostics Case Study: A 63 Year Old Man with Fatigue

The following case is an interesting overlap of Hematopathology and Molecular Diagnostics, and shows the utility of sequencing to detect a cancer before biopsy could.

A 63 year old gentleman presented to a heme/onc physician with six months of intractable anasarca, fatigue, and a recent mild thrombocytopenia (Table 1). They were otherwise in healthy condition. The physician initiated a lymphoma work-up that included a bone marrow biopsy. The tests were negative for M-protein.

Table 1. Summary of symptoms and relevant abnormal labs.

The bone marrow biopsy was somewhat limited, but the core contained multiple marrow elements. After a thorough review by a Hematopathologist, no evidence of dysplasia or other irregularities could be detected (Image 1). Flow cytometry detected no aberrant blast population. Cytogenetics detected 20del [16/20] and 5del [3/20]. These findings did not clearly indicate a specific diagnosis.

Image 1. 40x view of the bone marrow specimen at the initial presentation. No evidence of dysplasia was found.

As the clinical suspicion for a malignancy was high, the bone marrow specimen was sent for sequencing on a 1385-gene panel test. The test included tumor-normal matched DNA sequencing (“tumor” sample: bone marrow, normal: saliva), RNA whole transcriptome sequencing on the bone marrow, and Copy Number Variant (CNV) analysis. Tumor-normal matched sequencing helps rule out variants that are normal and present in the patient.

Somatic mutations were determined as those that were present in the “tumor” sample and not in the matched normal sample. The somatic variants found are listed below with their variant allele frequency (VAF) in parenthesis. Recall that a VAF of 40% means that a mutation is present in the heterozygous state in 80% of cells.

  • IDH2 (p.R140Q, 46%)
  • SRSF2 (p.P95T, 51%)
  • CBL (p.R499*, 47%)
  • KRAS (p.K117N, 12%)
Figure 1. View of IGV, which displays the NGS reads for IDH1 along with the variant allele highlighted in red. The color of the bars indicates the direction of the reads (forward in red and reverse in blue). This reflects the allele frequency of approximately 50%.

The mutations in these genes are commonly found in myeloid cancers including myselodysplastic syndrome. Activating mutation in IDH2 (isocitrate dehydrogenase 2) increase the production of the oncometabolite 2-HG, which alters methylation in cells taking them to an undiffereitiated state. SRSF2 (Serine And Arginine Rich Splicing Factor 2) is a part of the spliceosome complex, which regulates how sister chromatids separate from each other. Failures in the proper function of the complex creates genomic instability. CBL (Casitas B-lineage Lymphoma) is a negative regulator of multiple signaling pathways, and loss of function mutations (as seen here) lead to increased growth signals through several tyrosine kinase receptors. KRAS (Kirsten RAt Sarcoma virus) is an upstream mediator of the RAS pathway, which acquires mutations that lead to constitutive activation and sends growth signals to cells causing them to proliferate.

Furthermore the CNV analysis also found the heterozygous loss of chromosome 20 as reported in cytogenetics. CNV analysis did not detect chromosome 5 deletion, as it was below the limit of detection (20% for CNV analysis).

Figure 2. This plot shows the normalized read frequency of genes across each of the chromosomes is shown here. The drop at chromosome 20 is shown in a pale brown color on the right side of the graph. This is consistent with the cytogenetic findings. The loss of 5q isn’t seen as it is below the limit of detection of 30%.

These mutations are all individually common in MDS, but the co-occurance of each gives very strong evidence that MDS is the diagnosis (Figure 3). There have also been studies that provide prognostic implications for several of the genetic mutations present. Some mutations like SRSF2 or CBL at high VAF (>10%) indicate a poor prognosis, but mutations in IDH2 or TP53 at any frequency have not only a high chance of progression, but also a faster time to onset of disease. Another non-genetic risk factor for developing MDS is an elevated RDW, which we saw in our patient.

Figure 3. From Becker et al 2016.

All of these high-risk factors together led us to push for a diagnosis of MDS based off of molecular findings, and the patient was started on treatment with Azacitadine. Our assessment was confirmed 3 months later when, the patient’s follow up bone marrow biopsy showed significant progression with megakaryocytic and erythroid dysplasia and hyperplasia and reticulin fibrosis MF2 (Image 2). Aberrant blasts were detected (1-2%), but not elevated. This demonstrates how molecular findings predicted and predated the patient’s rapid progression to morphologic disease.

Image 2. Dysplastic, hyperplastic megakaryocytes and erythroid lineage.

In summary, multiple molecular mutations indicative of MDS were found in a symptomatic patient’s unremarkable bone marrow biopsy months before a rapid progression to MDS.

References

  1. Steensma DP, Bejar R, Jaiswal S et al. Blood 2015;126(1):9-16.
  2. Sellar RS, Jaiswal S, and Ebert BL. Predicting progression to AML. Nature Medicine 2018; 24:904-6.
  3. Abelson S, Collord G et al. Prediction of acute myeloid leukemia risk in healthy individuals. Nature 2018; 559:400-404.
  4. Desai P, Mencia-Trinchant N, Savenkov O et al. Nature Medicine 2018; 24:1015-23.
  5. Becker PM. Clonal Hematopoiesis: The Seeds of Leukemia or Innocuous Bystander? Blood.2016 13(1)

-Jeff SoRelle, MD is a Chief Resident of Pathology at the University of Texas Southwestern Medical Center in Dallas, TX. His clinical research interests include understanding how the lab intersects with transgender healthcare and improving genetic variant interpretation.

A 66 Year Old Male with Diarrhea, Weight Loss, and Night Sweats

Case History

A 66 year old man with past medical history of recently diagnosed Clostridioides difficile colitis presented to emergency department with diarrhea, weight loss of 52 pounds in 4 months, and occasional night sweats. CT imaging revealed dilation of small bowel with thickened mucosal folds. The duodenum was subsequently biopsied to reveal diffuse intestinal lymphangiectasia containing PAS positive and Congo red negative eosinophilic material and lamina propria foamy macrophages. Laboratory investigations revealed normocytic anemia, proteinuria, and peripheral IgM kappa monoclonal gammopathy.

Biopsy Findings

Image 1. Aspirate.
Image 2. Core biopsy.
Image 3. CD138.
Image 4. Kappa ISH.
Image 5. Lambda ISH.

Bone marrow aspirate shows increased plasma cells and mast cells. H&E stained sections demonstrate a normocellular bone marrow with trilineage hematopoiesis and involvement by 35% plasma cells. By immunohistochemistry, CD138 highlights clusters of plasma cells that predominantly express kappa light chain restriction.

FISH and Mutation Analysis

FISH demonstrated loss of chromosome 11 and gain of chromosome 15, which was consistent with plasma cell dyscrasia. MYD88 mutation analysis did not detect the mutation.

Diagnosis

The findings of the patient’s normocytic anemia, IgM monoclonal gammopathy, and intestinal lymphangectasia with an associated plasma cell dyscrasia involving the bone marrow favor a lymphoplasmacytic lymphoma/Waldenström macroglobulinemia.

Discussion

Waldenstrom macroglobulinemia (WM) is a malignant B-cell lymphoproliferative disorder characterized by lymphoplasmacytic infiltration of the bone marrow and peripheral IgM monoclonal gammopathy.1 It is rare with an overall incidence of 3 per million persons per year, accounting for 1-2% of hematologic cancers.1 It occurs predominantly in Caucasian males, with a median age of 63-68 years old at diagnosis.1-3

Patient may be asymptomatic for years and require observation or experience a broad spectrum of signs and symptoms. These symptoms may be attributable to the tumor infiltration of the bone marrow and lymphoid tissues, IgM circulating in the blood, and IgM depositing into tissues. The most common clinical presentation of WM is fatigue and nonspecific constitutional symptoms, such as fever, night sweats, and weight loss, due to normochromic, normocytic anemia. 20-30% of patients may exhibit lymphadenopathy and hepatosplenomegaly due to infiltration of peripheral tissues. High concentration of IgM in the circulation may lead to hyperviscosity, resulting in oronasal bleeding, gingival bleeding, blurred vision due to retinal hemorrhages, and neurological symptoms, including headache, ataxia, light-headedness, dizziness, and rarely, stroke.2-3 The gastrointestinal manifestations are rare; however, IgM monoclonal protein may deposit into the lamina propria of the GI tract, causing diarrhea, steatorrhea, and GI bleeding.4 Other IgM-related manifestations include cold agglutinin hemolytic anemia, cryoglobulin, and amyloid deposition in tissues.3

Diagnosis of WM includes evidence of IgM monoclonal gammopathy and at least 10% of bone marrow infiltration by lymphoplasmacytic cells.5 Monoclonal gammopathy can be detected by the monoclonal spike, or M-spike, on serum protein electrophoresis.3 Serum immunofixation may be performed to identify the type of monoclonal protein and the type of light chain involved.3 In terms of immunophenotype, neoplastic cells express surface IgM, cytoplasmic Igs, CD38, CD79a, and pan B-cell markers (CD19, CD20, and CD22). CD10 and CD23 are absent. Expression of CD5 occurs in approximately 5-20% of cases.6 Recent studies have reported two most common somatic mutations in WM, which are MYD88 L265P mutations (90-95% of cases) and CXCR4 (30–40% of cases).7 Absence of these mutations, however, do not completely exclude the diagnosis of WM.

The International Staging System for WM identifies five factors associated with adverse prognosis, including age older than 65, hemoglobin < 11.5g/dL, platelet count < 100K/μL, beta-2-microglobulin > 3mg/L, and monoclonal IgM concentration > 7g/L.3 Patients younger than the age of 65 years with 0 or 1 of these factors are in the low-risk category with a median survival of 12 years.3 In contrast, patients with 2 or more risk factors are in the intermediate- and high-risk categories and have a median survival of almost 4 years. 3

Management of WM depends on the patient’s clinical manifestations.Furthermore, patients with minimal symptoms should be managed with rituximab, whereas patients with severe symptoms related to WM should receive more aggressive treatment, including dexamethasone, rituximab and cyclophosphamide. Hyperviscosity syndrome is an oncologic emergency that requires removal of excess IgM from the circulation via plasmapheresis.8

References

  1. Neparidze N, Dhodapkar MV. Waldenstrom’s Macroglobulinemia: Recent advances in biology and therapy. Clin Adv Hematol Onco. 2009 Oct;7(10): 677-690.
  2. Leleu X, Roccaro AM, Moreau AS, Dupire S, Robu D, et al. Waldenstrom Macroglobulinemia. Cancer Lett. 2008 Oct;270(1):095-107.
  3. Tran T. Waldenstrom’s macroglobulinemia: a review of laboratory findings and clinical aspects. Laboratory Medicine. 2013 May;44(2):e19-e21.
  4. Kantamaneni V, Gurram K, Khehra R, Koneru G, Kulkarni A. Distal illeal ulcers as gastrointestinal manifestation of Waldenstrom Macroglbulinemia. 2019 Apr; 6(4):pe00058.
  5. Grunenberg A, Buske C. Monoclonal IgM gammopathy and Waldenstrom’s macroglobulinemia. Dtsch Arztebl Int. 2017 Nov;114(44):745-751.
  6. Bhawna S, Butola KS, Kumar Y. A diagnostic dilemma: Waldenstrom’s macroglobulinemia/plasma cell leukemia. Case Rep Pathol. 2012;2012:271407.
  7. Varettoni M, Zibellini S, Defrancesco I, Ferretti VV, Rizzo E, et all. Pattern of somatic mutations in patients with Waldenstrom macroglobulinemia or IgM monoclonal gammopathy of undetermined significance.
  8. Oza A, Rajkumar SV. Waldenstrom macroglobulinemia: prognosis and management. Blood Cancer Journal. 2015;5:e394.

-Jasmine Saleh, MD MPH is a pathology resident at Loyola University Medical Center with an interest in dermatopathology and hematopathology. Follow Dr. Saleh on Twitter @JasmineSaleh.

–Kamran M. Mirza, MD, PhD, MLS(ASCP)CM is an Assistant Professor of Pathology and Laboratory Medicine, Medical Education and Applied Health Sciences at Loyola University Chicago Stritch School of Medicine and Parkinson School for Health Sciences and Public Health. A past top 5 honoree in ASCP’s Forty Under 40, Dr. Mirza was named to The Pathologist’s Power List of 2018 and placed #5 in the #PathPower List 2019. Follow him on twitter @kmirza.

Hematology Case Study: The Story of the Platelet Clump: EDTA-Induced Thrombocytopenia

I belong to a Hematology Interest Group and always enjoy seeing the case studies and questions that other techs post. This group is multinational so I see posts from techs all over the world. It’s interesting to see the similarities and differences in standard operating practices and the roles techs play in different areas and different countries. It’s also interesting to see that we all come across the same types of problems and difficult specimens! In the last few months in this Hematology Interest Group, I have seen many questions and comments about resolving clumped platelets, and am therefore using this opportunity to shed some light on these tricky specimens. The case I am presenting, and the photos, are courtesy of Abu Jad Caesar, who is a Lab manager at Medicare Laboratories – Tulkarm branch, in Palestine.

The patient had a CBC performed on a Nihon Kohden 6410. WBC was 12.7 x 103μL, impedance platelet count was 20,000/μL on initial run, other parameters appeared within normal limits. The sample was warmed and a Na Citrate tube was requested to rule out pseudothrombocytopenia. After warming, the EDTA was rerun with a platelet count of 0/μL. The Na Citrate tube was run, and platelet count from the instrument was 189,000/μL. (Figure 1) Because of the blood:anticoagulant ratio in the Na Citrate tube, a multiplier of 1.1 was applied, thus making the Na Citrate platelet count 207,900/μL. Slides were made, stained and examined. Image 1 shows the clumping in the EDTA tube. Image 2 shows the smear from the Na Citrate tube, with no visual clumping.

The CBC was reported with the following comments: Platelet clumping observed, 2 samples drawn to rule out thrombocytopenia. EDTA whole blood smear had many platelet clumps noted (EDTA induced thrombocytopenia). Conclusion: Platelets are adequate and estimated to be about 200,000/μL.

Figure 1. Results from warmed EDTA tube (left) and Na Citrate tube (right).
Image 1. Clumped platelets seen with EDTA.
Image 2. Normal platelet count with no clumping seen with Na Citrate.

Platelet counts in the normal range don’t usually give us too much trouble in reporting, even if some clumping is present, mainly because they are normal. Adequate platelet counts fall within a typical reference range of about 150- 450 x 103/μL. If there are instrument flags for a platelet abnormal scattergram or platelet clumps, it is recommended to repeat testing by another method. If the initial count is performed by impedance counting, many analyzers can also report optical or fluorescent platelet counts. With impedance counting, very small RBCs or fragments may be counted as platelets, thus giving a falsely increased platelet count. With optical counting, large platelets can be counted as RBCs, thus giving a falsely decreased count. Some Sysmex hematology analyzers use impedance and optical counts and also feature fluorescent platelet counts which use a platelet specific dye and give accurate platelet counts without the interferences of other methods. A normal platelet count, even with clumping seen on a smear, is still usually estimated to be normal (or may occasionally be increased.)

Thrombocytopenia, on the other hand, can be a challenge in the hematology laboratory. With thrombocytopenia, physicians need an accurate count to diagnose, treat or monitor patients. Even a small increase or decrease can be significant when there is a severe thrombocytopenia. With fewer platelets, every platelet counts!

One of the first questions we must ask with an apparent thrombocytopenia is if this is a true thrombocytopenia or if it is pseudothrombocytopenia (PTCP). A true thrombocytopenia represents a patient with a low platelet count who may need monitoring or medical intervention. It can be dangerous to miss true thrombocytopenia but is also dangerous to report a low platelet count in a patient with a spurious thrombocytopenia who is not actually thrombocytopenic. Pseudothrombocytopenia, or spurious thrombocytopenia, is defined as an artificially or erroneously low platelet count. In PTCP, the low platelet count is due to clumps that are counted as 1 platelet. (These large clumps can also be counted as WBCs, thus giving a falsely increased WBC count.)

We can divide PTCP into 2 categories Platelet clumping is most commonly caused by pre-analytic errors such as over-filled or under-filled EDTA tubes, clotted specimens, or a time delay between sample collection and testing. Techs should check the tube for clots and sample volume and do a delta check to help differentiate thrombocytopenia and PTCP. But, with an apparent ‘good’ sample, the next step would be a smear review. If there are clumps seen on the smear, then we need to decide what caused the clumps. Is it the first category, one of these common pre-analytical issues, or is it the 2nd category of PTCP, an in vitro agglutination of platelets? Conditions that can cause this in vitro agglutination of platelets include cold agglutinins, multiple myeloma, infections, anticardiolipin antibodies, high immunoglobulin levels, abciximab therapy and EDTA induced pseudothrombocytopenia. (EDTA-PTCP) Of these, EDTA induced pseudothrombocytopenia is the most common cause. (Nakashima, 2016).

When techs talk about platelet clump issues, it is usually because we are looking for ways to resolve or to accurately estimate the platelet count in these samples, and there doesn’t seem to be one easy answer. The clumping makes precise counting impossible and even estimates can be very tricky. How can we estimate these counts? Do we simply report the presence of clumping with “appear normal”, “decreased” or “increased”? Or, should we break our estimates into more ranges to give physicians more valuable information? And, what if the provider wants an actual count in order to give the patient the best care possible and we can’t resolve the clumping? What can we do to provide a count? Some of the first steps recommended include vortexing the sample for 2 minutes to break up platelet clumps, then re-analyzing. Warming samples may also help to resolve platelet clumps, particularly in samples with cold agglutinins or that have had a delay in testing and have been transported or stored at room temperature or below. If clumps persist and recollecting the sample still yields platelet clumping, then pre-analytical error can be ruled out an EDTA induced pseudothrombocytopenia may be suspected. Many labs will have an alternate tube drawn or use another method to help resolve the clumping.

So, what is EDTA induced thrombocytopenia (EDTA-PTCP)? This is not representative of a particular clinical picture, and is not diagnostic for any disorder or drug therapy, but is a laboratory phenomenon due to presence of EDTA dependent IgM/IgG autoantibodies. These antibodies bind to platelet membrane glycoproteins in presence of EDTA. EDTA induces and enhances this binding by exposing these glycoproteins to the antibodies. (Geok Chin Tan, 2016) Though it is an in vitro phenomenon, patients with certain conditions, such as malignant neoplasms, chronic liver disease, infection, pregnancy, and autoimmune diseases, do have increased risk of EDTA-PTCP. However, EDTA-PTCP has also been observed in patients who are disease free. (Zhang, 2018)

What are some alternate methods to help resolve EDTA induced platelet clumping challenges? Probably the most common is to redraw the sample in a Na Citrate tube. Both EDTA and Na Citrate tubes should be drawn. In a true EDTA-PTCP, as seen in our case study, you should see clumps on the smear made from the EDTA tube and no clumps on the smear made from the Na Citrate tube. Because of the volume of the anticoagulant in the Na Citrate tube you must also apply the dilution factor of 1.1 to the count from the Na Citrate tube to get an accurate platelet count. Note, however, that hematology analyzers are FDA approved and validated for use with EDTA tubes. If you wish to use a different anticoagulant, the method must be validated in your laboratory. Note also that alternate methods will generally only resolve EDTA -PTCP, and not clumping due to other cold agglutinins, medication or disorders. In addition, anticoagulant induced thrombocytopenia is not limited to EDTA. It can also occur with citrate and heparin. In a study, it was found that up to 17% of patients with an EDTA -PTCP also exhibited this phenomenon with citrate. In fact, researchers have found, and we have found in our own validations, that some samples that do not clump in EDTA actually DO clump in Na Citrate. Thus, alternate tubes may not resolve all platelet clumping. (Geok Chin Tan, 2016)

Some labs have validated ACD (Citric acid, trisodium citrate, dextrose) anticoagulant tubes for EDTA-PTCP. Using this method, the EDTA tube and ACD must be run in parallel and a conversion factor applied, reflecting the difference in sample dilution in the 2 tubes. A parameter such as the RBC must be chosen to make this comparison. Using a formula that divides the RBC in EDTA by the RBC in ACD gives a ratio that reflects the dilutional differences between anticoagulants. This ratio can then be multiplied by the ACD platelet count to obtain the ACD corrected platelet count. (CAP Today, 2014). Some sources have recommended ACD tubes because the incidence of clumping with Na Citrate can be frustratingly high. It is theorized that the more acidic ACD tube may prevent platelet clumping better than Na Citrate. (Manthorpe, 1981)

Less commonly used tubes are CTAD (trisodium citrate, theophylline, adenosine, dipyridamole) and heparin. CTAD acts directly on platelets and inhibits platelet factor 4 thus minimizing platelet activation. Downsides to CTAD tubes are that they are light sensitive and must be stored in the dark, and can be costly. They also alter the blood/additive dilution ratio so calculations must be used, as seen with Na Citrate and ACD. Heparin tubes are less commonly found to be beneficial in resolving platelet clumping issues because heparin can active platelets. Heparin tubes are also more expensive, so have not generally been a first choice for EDTA-PTCP.

I have heard from techs that their labs have very good results using amikacin added to EDTA tubes to prevent spuriously low platelet counts in patients with EDTA-PTCP. Amikacin should be added to the EDTA tube within 1 hour after draw and testing is stable for up to 4 hours at room temperature. Results of a study done in 2011 showed that the addition of amikacin to the EDTA tube produced rapid dissociation of the platelet clumps with little or no effect on morphology or indicies. This method has proved very promising for reporting accurate platelet counts in patients with multianticoagulant induced PTCP. (Zhou, 2011)

The last anticoagulant tube that I have seen mentioned by many techs in the hematology interest group are Sarstedt ThromboExact tubes. I have seen many posts from techs who use these and they seem to have a very good success rate. ThromboExact tubes contain magnesium salts and are specifically designed to determine platelet counts in cases of PTCP. They are currently validated only for platelet counts and samples are stable for 12 hours after collection. Interestingly, before automated hematology analyzers, magnesium was the anticoagulant of choice for manual platelet counts. EDTA-PTCP has been recognized since EDTA automated platelet counts were introduce in the 1970s. A 2013 study in Germany used ThromboExact tubes with excellent results for resolving multianticoagulant induced PTCP. These tubes became commercially available during the study, in 2013. (Schuff-Werner, 2013) Unfortunately for us in the United States, these tubes are not available in the US. I was recently at a conference and went up to the Sarstedt representatives and asked about these tubes. I was told that they are available in parts of Europe and Asia but are not FDA approved in the US. I asked very hopefully if they were looking at getting FDA approval and was unfortunately told that “they didn’t think they had the market for them to pursue approval.”

Whichever alternative method your lab chooses to use, it is recommended to draw an EDTA and the alternate tube together. This way the 2 counts and the presence or absence of clumping in the tubes can be compared. We have many patients who had one incidence of clumping, yet when the provider orders a Na Citrate platelet count, we get a new draw of both EDTA and Na Citrate tubes together, and there is no flagging or clumping seen with EDTA. In these cases it is appropriate to result the EDTA results as there is no evidence of EDTA-PTCP.

When a patient has a low PLT count without any hematologic disease, family history, and/or bleeding-tendency identified, and pre-analytical errors have been ruled out, PTCP should be considered. This does not mean that a patient with PTCP will have a normal platelet count after the clumping is resolved. As stated above, many patients with EDTA-PTCP have hematological or other disorders and may be truly thrombocytopenic. Resolving the clumping in these patients allows us to give the provider an accurate platelet count, which is very important in thrombocytopenic patients.

The flow chart below (Figure 4) shows some things to consider when dealing with platelet clumping. It is our goal to resolve clumping so that we can report an accurate platelet count in a timely fashion. In the laboratory where I work, I have validated Na citrate tubes, but these seem to resolve clumping in less than 50% of patients. As a last resort, to get an accurate platelet count, some articles have suggested collecting a fingerstick and performing manual counts. I did include this in the chart as an option for multianticoagulant PTCP, however, due to the difficulty in collecting a good specimen and the subjectivity of counts, along with problems associated with necessary calculations, our pathologists have decided that we will not do manual platelet counts. For this reason, I am currently involved in platelet clumping monitoring and will be conducting a small internal study to compare ACD, CTAD and Na Citrate tubes in parallel. Depending on those results we may also then test amikacin. If we come to any enlightened conclusions I’ll write another short blog with our results!

Thanks again to Abu Jad Caesar, lab manager at Medicare Laboratories – Tulkarm branch, in Palestine, who provided me with this textbook perfect case of PCTP, which was easily resolved by collecting in Na Citrate. We wish they all read the textbooks and were as cooperative!

Figure 2. Flowchart for resolving and reporting of thrombocytopenia.

References

  1. CAP Today, January 2014. accessed online http://www.captodayonline/qa-column-0114
  2. Manthorpe R, Kofod B, et al. Pseudothrombocytopenia, In vitro studies on the underlying mechanisms. Scand J Haematol 1981; 26:385-92
  3. Nakashima MO, Kottke-Marchant K. Platelet Testing: In: Kottke-Marhchant K, ed. An Algorithmic Approach to Hemostasis Testing, 2nd ed. CAP Press; 2016:101
  4. Schuff-Werner,Peter, et al. Effective estimation of correct platelet counts in pseudothrombocytopenia using an alternative anticoagulant based on magnesium salt. Brit J of Haematol Vol 162, Issue 5. June 29, 2013
  5. Tan, Geok Chin et al. Pseudothrombocytopenia due to platelet clumping: A Case Report and Brief Review of the Literature. Case Reports in Hematology. Volume 2016
  6. Lixia Zhang, MMed,* Jian Xu, MD,* Li Gao, MMed, Shiyang Pan, MD, PhD. Spurious Thrombocytopenia in Automated Platelet Count. Laboratory Medicine 49:2:130-133. 2018
  7. Zhou,Xiamian, et al. Amikacin can be added to blood to reduce the fall in platelet count. Am Journal of Clinical pathology, Vol 136, Issue 4, Oct 2011.

-Becky Socha, MS, MLS(ASCP)CM BB CM graduated from Merrimack College in N. Andover, Massachusetts with a BS in Medical Technology and completed her MS in Clinical Laboratory Sciences at the University of Massachusetts, Lowell. She has worked as a Medical Technologist for over 30 years. She’s worked in all areas of the clinical laboratory, but has a special interest in Hematology and Blood Banking. When she’s not busy being a mad scientist, she can be found outside riding her bicycle.

Hemoglobin Electorphoresis in Children

This last month, I rotated through our Children’s hospital, which included reviewing hemoglobin electrophoresis tests. I’d learned about them before in residency, but they can be quite more interesting (complicated) than I expected.

Hemoglobin electrophoresis is a blood test to look at different types of hemoglobin to determine if there are any abnormalities. In a children’s hospital it is frequently ordered as a reflex for an abnormal newborn screen or when a child is incidentally found to be anemic. The test is performed in 2 stages. 1st lysed blood samples are run on gel electrophoresis and different types of hemoglobin are separated as they move at different speeds. Several types of hemoglobin will run within the same region, so a secondary method of separation is always employed.

Below, you can see how some bands in the same area of an acidic gel (agarose) are actually very different on the alkaline gel (cellulose acetate) and vice versa.

At our hospital, we use HPLC and measure retention times of the hemolysate to quantify and identify different hemoglobin types present. As a basic primer you should recall that hemoglobin is a tetramer with a pair of alpha globin + a pair of either beta, delta or gamma globin (each separate genes).

Alternative hemoglobins are enriched in populations where malaria is endemic as these variants may provide improved fitness by promoting resistance to the malarial parasite that reproduces inside red blood cells. Thus, many people of African or south east Asian descent may carry these variants.

Our case is that of a 2 year old girl with anemia who had testing sent by her primary care doctor for the following CBC:

This is indicative of microcytic anemia, but unlike some Thalessemias the RBC isn’t very high. More on this later.

Looking at the gel result, there is a large band in the area coinciding with Hgb C. We also see the normal Hgb A2 and a small amount of Hgb F. We know Hgb F can be increased in Hgb SS and thus could also be present if she had Hgb C trait or disease.

InkedBlog 1B_LI

Looking at the next HPLC result, we see there is a similar very high level of Hgb C (68%) with corresponding levels of Hgb F and Hgb A2 (note: acetylated Hgb F and Hgb F are added together). Thus, this fits with a homozygous C with some compensatory A1 and F, right?

Remember Hgb C is a β -globin variant and you only have 2 β -globin genes, so if you are homozygous for the C variant on the β-globin gene (HBB), then Hgb A1, which is made of normal β-globin would be impossible to produce. Also you might be bothered by all of these small peaks. However, there are often small peaks that can’t be definitively identified and are likely post-translationally modified hemoglobin. But in the context of an abnormal Hgb A1 that shouldn’t be there, we dug deeper.

One of the most common hemoglobinopathies is Beta Thalassemia (β-Thal), which clinically manifests when less of the beta hemoglobin protein is produced. Heterozygous mutations lead to Beta Thalassemia minor with minimal symptoms, while homozygous mutations lead to β-thal major with symptoms of anemia. Mutations in the β -globin gene, HBB, can lead to complete loss of β-globin (β0 variant) or partial of β-globin (β+ variant).

As this patient has less than 50% of Hgb A present (expected amount), they could also have a β+ variant as well. This would make them compound heterozygous for C and β+.

One of the hallmarks of Thalassemia is an increase in Hgb A2 (normal 2.5-3.5%). Hemoglobin A2 is a normal variant of A that is composed of two alpha and two delta chains (δ2α2). We see in our case that the Hgb A2 is normal at 2.5%. So it seems the patient doesn’t display a typical Thalassemia picture.

One condition that could create this scenario is if there is a variant in the delta chain of A2 that causes it to elute differently. Indeed, there is a delta variant that creates hemoglobin A2 prime (A2’) that moves near the S region of the HPLC. And when we look back at our unknown hemoglobins, Hgb X is marked at 1.03 of the S region and has an abundance of 3.9%. This supports it being the Hgb A2’ and if we add this together with the Hgb A2 we get an elevated 6.6% A2 total, which would be consistent with Beta Thalassemia. Lastly, one would wonder if we could find this third hemoglobin variant A2’ on the alkaline gel. Previous studies have shown the A2’ variant is more negatively charged, so on a basic gel, it should move further from the negative anode than the other hemoglobins. We don’t see anything to the left of the HgbC, but if we flip the gel over and look under the patient label, you can see a faint band that is likely the A2’!

In summary this case arose from 3 separate mutations in a single patient. She was compound heterozygous for a Hgb C and β+ variants in the β-globin gene and she was heterozygous for an A2’ variant on the delta-globin gene.  This was certainly a case where paying close attention mattered.

References:

  1. Abdel-Gadir D, Phelan L, and Bain BJ. Haemoglobin A2′ and its significance in beta thalassaemia diagnosis. Int J Lab Hematol. 2009 Jun;31(3):315-9. doi: 10.1111/j.1751-553X.2008.01038.x. Epub 2008 Feb 21.
  2. https://ghr.nlm.nih.gov/condition/beta-thalassemia

-Dr. Charles Timmons MD PhD is a pediatric pathologist at Children’s Medical Center in Dallas, TX. His responsibilities include signing out hemoglobin electrophoresis, HPLC and globin sequencing, and has been residency director for 17 years.

-Jeff SoRelle, MD is a Chief Resident of Pathology at the University of Texas Southwestern Medical Center in Dallas, TX. His clinical research interests include understanding how the lab intersects with transgender healthcare and improving genetic variant interpretation.

Hematopathology Case Study: An 80 Year Old Man with Rapid Onset Cervical Adenopathy

Case History

An 80 year old man presented with rapid onset of cervical adenopathy over a period of few months. The largest lymph node measuring 6 cm was biopsied and sent for histopathological evaluation.

Biopsy Findings

Sections from the lymph node showed effacement of the lymph node architecture by a fairly monotonous population of medium to large sized lymphoid cells arranged in vague nodular pattern. Focally, a starry sky pattern was observed. The cells were 1.5-2 times the size of an RBC, with high N:C ratio, irregular angulated nuclei and small nucleoli. A high mitotic rate of 2-3 mitoses/hpf was seen.

Immunohistochemistry

Immunohistochemical stains showed that the lymphoma cells were positive for CD20, CD5, SOX-11, and negative for Cyclin D1, CD10, CD23, CD30, BCL-1, and BCL-6. Ki67 index was about 70%.

Diagnosis

A diagnosis of Mantle cell lymphoma, pleomorphic variant was made.

Discussion

Mantle cell lymphoma is a peripheral B cell lymphoma, occurring in middle aged or older adults, with a male: female ratio of 7:1. Although Cyclin D1 expression is considered a hallmark of mantle cell lymphoma, yet about 7% cases are known to be Cyclin D1 negative. In these cases, morphological features and SOX-11 positivity helps in establishing a definitive diagnosis.

Differential Diagnosis

In the assessment of morphological features of lymphoma, the cell size is an important starting point. In this case, the lymphoma cells ranged from medium to large sized. The following differential diagnoses were considered:

  • Burkitt lymphoma

This case showed a “starry sky” pattern focally. A medium sized population of cells, high mitotic rate and a high Ki67 index (70%) favoured a Burkitt lymphoma. However, although commonly seen in Burkitt lymphoma, a “starry sky” pattern is not specific for this type of lymphoma. Also, the lack of typical “squaring off” of nuclei, basophilic cytoplasmic rim were against the diagnosis of Burkitt lymphoma. The nuclei in this case showed 0-1 small nucleoli, unlike the typical basophilic 2-3 prominent nucleoli of Burkitt lymphoma. Moreover, Ki67 index, even though high was not enough for Burkitt lymphoma where it approaches 100%. The cells were negative for CD10 and Bcl-6, which are almost always found in a Burkitt lymphoma. Hence, a diagnosis of Burkitt lymphoma was ruled out.

  • Diffuse Large B cell Lymphoma

The presence of interspersed large cells with nucleoli, irregular nuclei, high mitotic rate, and a high Ki67 index with a history of very rapid enlargement of lymph node suggested a diagnosis of Diffuse Large B cell lymphoma. However, the scant cytoplasm, lack of bizarre cells, and absence of CD10, BCl-2, BCl-6 were against a diagnosis of DLBCL.

  • Lymphoblastic lymphoma

A diagnosis of lymphoblastic lymphoma was favoured by the irregularly angulated nuclei, and presence of nucleoli. However, the cells of lymphoblastic lymphoma have a more delicate nuclear chromatin, higher mitotic rate as against the relatively condensed chromatin and the low to high variable mitotic rate of Mantle cell lymphoma. Also, lymphoblastic lymphomas are more commonly of the T cell subtype and occur commonly in younger individuals. In this case, B cell markers were positive (CD 20), and the patient was 80 year old, disfavouring a lymphoblastic lymphoma. The blastoid variant of mantle cell lymphoma is practically indistinguishable from lymphoblastic lymphoma, except that it is Tdt negative.

Cyclin D1 negativity in Mantle cell lymphoma

In the cases of Cyclin D1 negative mantle cell lymphomas, morphology plays a critical role in coming to a diagnosis of mantle cell lymphomas. In this case, points that favoured the diagnosis of mantle cell lymphoma were clinical features such as older age (80 years), and male gender, and morphological features such as a vaguely nodular pattern of growth, irregular nuclei, and 0-1 small nucleoli. Due to the presence of variably sized cells with distinct nucleoli, a pleomorphic variant was considered. Even though Cyclin D1 was found to be negative, the cells were positive for SOX-11.

SOX-11 is a transcription factor that is not normally expressed in B cells, but is sensitive and fairly specific for mantle cell lymphomas. It is important to note that SOX-11 is also positive in 25% Burkitt lymphoma, 100% lymphoblastic lymphoma, and 66% T-prolymphocytic leukemia. Herein lies the importance of recognising morphological features, as all of these lymphomas that may express SOX-11 were ruled on the basis of morphology. A more specific antibody, MRQ-58 may be used for greater specificity. The presence of SOX-11 is considered a specific biomarker for Cyclin-D1 negative mantle cell lymphomas. In these cases, there is upregulation of Cyclin D2 or D3 that may substitute for Cyclin D1 upregulation. But, immunohistochemical detection of Cyclin D2 or D3 is not helpful for establishing a diagnosis, as other lymphomas are commonly positive for these markers. Hence, it is important to perform SOX-11 immunohistochemistry to diagnose the Cyclin D1 negative variant of mantle cell lymphoma.

SOX-11 can be used not just for the diagnosis, but also for determining prognosis of mantle cell lymphoma. Indolent MCL usually lack SOX-11 expression. The pattern of SOX-11 staining has also been used a marker of prognosis. Cytoplasmic expression of MCl, seen in only a few cases was associated with a shorter survival as compared to the more common nuclear staining of SOX-11.

Conclusion

In this age, lymphoma diagnosis relies heavily on the use of immunohistochemical markers. However, this case highlights the importance of morphological features in diagnosing lymphomas with unusual immunohistochemical marker profile. Although, this case was negative for Cyclin D1, considered a hallmark of Mantle cell lymphoma, yet, the combination of morphological features with SOX-11 staining helped in clinching the diagnosis. To avoid a misdiagnosis, it would be prudent to perform SOX-11 staining in all lymphoma cases morphologically resembling MCL, but lacking Cyclin-D1.

-Swati Bhardwaj, MD has a special interest in surgical pathology and hematopathology. Follow her on Twitter at @Bhardwaj_swat.

–Kamran M. Mirza, MD, PhD, MLS(ASCP)CM is an Assistant Professor of Pathology and Laboratory Medicine, Medical Education and Applied Health Sciences at Loyola University Chicago Stritch School of Medicine and Parkinson School for Health Sciences and Public Health. A past top 5 honoree in ASCP’s Forty Under 40, Dr. Mirza was named to The Pathologist’s Power List of 2018 and placed #5 in the #PathPower List 2019. Follow him on twitter @kmirza.

Hematology Case Study: Thrombocytopenia in a 4 Year Old Child

A 4 year old child was brought to the pediatrician by her mother with a complaint of new onset of severe bruising on her legs. The mother could not recall any falls or bumps that would have caused the bruising. On exam, the physician also noted mucosal bleeding in the oral cavity. Questioning revealed that the patient had experienced flu like symptoms several weeks earlier. The physical exam was normal except for the bleeding. There was no family history of bleeding disorders. A CBC was ordered.

Reported CBC Results

WBC, RBC, Hgb, Hct, RBC indicies normal

Platelet count 26 x 103/μL

IPF 22% (reference range IPF% 1.0-7.0%) The physician evaluated the results, noting the normal CBC but decreased platelet count. The above results also show the immature platelet fraction (IPF), an additional Advanced Clinical Parameter reported from the Sysmex XN hematology analyzer. A low platelet count, as seen in this patient, will reflex a fluorescent platelet count (PLT-F). The impedance count (PLT-I) can be falsely increased if small RBCs or fragments are counted as platelets. On the other hand, in an optical platelet count, when measuring platelets by size (PLT-O), large platelets can be missed, giving a falsely low count. In this case there was a low platelet count and an instrument flag for an abnormal platelet scattergram. The PLT-F, on the other hand, uses a platelet specific dye which eliminates interference seen with other methods. The fluorescent dye labels the RNA, and forward scatter is used to determine size while side fluorescence is used to measure RNA content. With gating set based on cell volume and RNA content, the PLT-F can be measured. Therefore, the reflexed and more reliable PLT-F was the reported count.

Figure 1. PLT-F scattergram. The PLT-F channel measures forward scatter (FSC) on the Y axis and side fluorescence (SFL) on the X axis.1

Additionally, when there is an abnormal scattergram or a low platelet count, the IPF% and IPF# are also reported. The immature platelet fraction is a measure of the youngest platelets, or reticulated platelets. These are the first circulating platelets, right out of the bone marrow. An increased IPF indicates an increase in platelet production, yet this child’s platelet count was very low. This suggests that the thrombocytopenia may be due to excessive destruction of platelets; the bone marrow was actively making platelets, but they were being destroyed, causing the low platelet count.

Figure 2. Platelet scattergrams from a healthy individual with a normal IPF (a) and a patient with a high IPF (b). Mature platelets appear as blue dots, green dots represent the IPF with increased cell volume and higher fluorescence intensity compared to mature platelets.1

Diagnosis

Immune Thrombocytopenia- ITP.

Primary immune thrombocytopenia (ITP), formerly known as idiopathic thrombocytopenic purpura or immune thrombocytopenic purpura, is one of the most common bleeding disorders of children. In most cases, it presents with sudden onset of bruising and petechiae in an otherwise healthy child, with normal WBC and hemoglobin. ITP is an autoimmune bleeding disorder in which the immune system makes anti-platelet antibodies which bind to platelets and cause destruction. Even though the exact cause of ITP remains unknown, it is recognized that it can follow a viral infection or live vaccinations. While there are some similarities between pediatric ITP and ITP in adults, in children this tends to be an acute disease which is self-limiting and resolves itself in several weeks, with no treatment. However, in a small number of children, the disorder may progress to a chronic ITP. In contrast to ITP in children, a chronic form is more commonly seen in adults. It is usually a diagnosis of exclusion, does not follow a viral illness and requires treatment.

This patient recovered in a few weeks. One month after the initial episode, her PLT was 174 x 103/μL and her IPF% was 6.0%

Conclusion

An IPF reported with a CBC, in combination with a low platelet count, is fast, inexpensive, and can be extremely beneficial in aiding in a timely diagnosis. As the child’s platelet count recovered, the IPF% returned to normal range. ITP can therefore be monitored with a CBC. Thus, the IPF can be used not only to help diagnose but also as an indicator of remission.

References

  1. Sysmex America, 2019. www.sysmex.com/us. Used with permission
  2. Arshi Naz et al. Importance of Immature platelet Fraction as a predictor of immune thrombocytopenic purpura. Pak J Med Sci 2016 Vol 32 No 3:575-579
  3. Briggs,C. Assessment of an immature plateletfraction (IPF) in peripheral thrombocytopenia. Br J Haematol 2004Jul;126(1):93-9
  4. Sysmex White Paper. The role of the ImmaturePlatelet Fraction(IPF) in the differential diagnosis of thrombocytopenia. www.sysmex.com/us
  5. D-Orazio, JA, Neely, J, Farhoudi,N. ITP in children: pathophysiology and current treatment approaches.J Pediatr Hematol Oncol.2013 Jan;35(1): 1-13

-Becky Socha, MS, MLS(ASCP)CM BB CM graduated from Merrimack College in N. Andover, Massachusetts with a BS in Medical Technology and completed her MS in Clinical Laboratory Sciences at the University of Massachusetts, Lowell. She has worked as a Medical Technologist for over 30 years. She’s worked in all areas of the clinical laboratory, but has a special interest in Hematology and Blood Banking. When she’s not busy being a mad scientist, she can be found outside riding her bicycle.

Hematopathology Case Study: A 69 Year Old Male with Weight Loss and Generalized Lymphadenopathy

Case History

The patient is a 69 year old male who presented to the hospital with a 3-month history of drenching night sweats, weight loss, fatigue, and generalized lymphadenopathy. He also endorsed a very itchy rash all over his body. He denied smoking. There was no other relevant social or family history.

Physical examination confirmed diffuse lymphadenopathy, hepatosplenomegaly and a mild diffuse skin rash. Notably, there was a 2.5 cm level-1 lymph node palpated in the left neck. This was subsequently biopsied.

Biopsy

Biopsy of the level-1 neck lymph node revealed a 2.3 x 1.5 x 1.2 cm mass pink-tan and firm mass. Sectioning revealed a glossy white-tan cut surface. H&E staining revealed a polymorphic lymphocytic infiltrate of in the interfollicular zones. The infiltrating lymphocytes ranged from small to large cells with abundant cytoplasm, eosinophils, and plasma cells. There was also a notable increase in the number of high endothelial vessels lined by lymphocytes with irregular nuclear borders and clear cytoplasmic zones.

Image 1. Polymorphic infiltrate of small, mature appearing lymphocytes (A), with prominent blood vessels and clear cytoplasm (B). Most of these cells were CD3 positive T cells (C) with expanded CD21 positive FDC meshworks (D) and scattered CD30 positive immunoblasts (E)

Further characterization by immunohistochemical staining showed the majority of the interfollicular cells to be CD3 and CD5 expressing T cells. These were a mix of CD4 and CD8 positive cells but with marked CD4 predominance. CD7 appeared positive in a smaller population of T-cells compared to CD3 (consistent with loss of this pan-T-cell marker). Varying numbers of the interfollicular cells were positive for CD10, BCL-6, CXCL-13, and PD-1 with a strong positivity for ICOS, phenotypically consistent with an expansion of Tfh (T-follicular helper cell) cells.

Interspersed between the T cells were numerous CD20 positive cells with prominent nucleoli that also revealed CD30 positivity. CD21 staining revealed expanded follicular dendritic cell meshworks. EBER ISH was positive in a rare subset of cells. Kappa and lambda ISH showed an increased number of polytypic plasma cells.

Flow Cytometry showed the presence of a small population of T-cells that were CD4 positive but CD3 negative. There was no evidence of B-cell clonality. TCR-G PCR was positive.

A final diagnosis of Angioimmunoblastic T-cell lymphoma (AITL) was rendered.

Discussion

AITL is a relatively rare neoplasm of mature T follicular helper cells, representing about 1-2% of all non-Hodgkin lymphomas. It is; however, one of the more common subtypes of peripheral T-cell lymphomas, accounting for 15-30% of this subgroup. The condition was first reported in 1974 in Lancet as a non-neoplastic abnormal immune reaction1. It was first recognized as a distinct clinical entity in in 1994 in the Revised European American Lymphoma Classification2. The disease shows a geological preference to Europe (28.7%) over Asia (17.9%) and North America (16%). AITL occurs primarily in middle aged and elderly individuals and shows a slight predominance of males over females.

The disease has a strong association with EBV infection, but the neoplastic T-cells are almost always EBV negative, creating an interesting question of EBV’s function in the etiology of AITL. AITL most often presents late in the disease course with diffuse systemic involvement, including hepatosplenomegaly, lymphadenopathy and other symptoms such as rash with pruritis and arthritis. Lab findings include cold agglutinins, rheumatoid factor and anti-smooth muscle antibodies. There also tends to be immunodeficiency secondary to the neoplastic process. The clinical course of AITL is variable, but the prognosis is poor, with the average survival time after diagnosis being < 3 years. The histological features and genetic findings have not been found to impact clinical course.

Microscopically, AITL presents with either partial or total effacement of the normal lymph node architecture with perinodal infiltration. The cells of AITL are small to medium-sized lymphocytes with clear to pale cytoplasm, distinct cell membranes and very minimal cytological atypia. These cells often congregate around the high endothelial venules. The T-lymphocytes are present in a largely polymorphous inflammatory background of other lymphocytes, histiocytes, plasma cells and eosinophils. There are 3 overlapping sub-patterns of AITL. The first of these is similar to a reactive follicular hyperplasia, and can only be distinguished from normal hyperplasia by use of immunohistochemical stains to differentiate the neoplastic cells from normal reactive cells. The second pattern has retained follicles, but they show regressive changes. The third pattern has completely or sub totally effaced. These three patterns seem to be on a spectrum with one another, given that progression from the first to the third pattern has been seen on consecutive biopsies in the same patient.

Cytologically, AITL cells express pan-T-cell markers including CD2, CD3 and CD5 and the vast majority are CD4 positive. CD3 may be quantitatively decreased or absent by flow cytometry. There are a variable number of CD8 positive T-cells. The tumor cells also show the immunophenotyping of normal T follicular helper cells including CD10, CXCL13, ICOS, BCL6 and PD1 in 60-100% of cases. CXCL13 and CD10 are the most specific, whereas PD1 and ICOS are the most sensitive.

References

  1. Horne, C., Fraser, R., & Petrie, J. (1974). Angio-Immunoblastic Lymphadenopathy With Dysproteinemia. The Lancet, 304(7875), 291. doi:10.1016/s0140-6736(74)91455-x
  2. Harris, N.l. “A Revised European-American Classification of Lymphoid Neoplasms: a Proposal from the International Lymphoma Study Group.” Current Diagnostic Pathology, vol. 2, no. 1, 1994, pp. 58–59., doi:10.1016/s0968-6053(00)80051-4.
  3. Swerdlow, Steven H. WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues. International Agency for Research on Cancer, 2017.
  4. “Angioimmunoblastic T Cell Lymphoma.” Pathology Outlines – PathologyOutlines.com, http://www.pathologyoutlines.com/topic/lymphomanonBAITL.html.

-Zachary Fattal is a 4th year medical student at the Central Michigan University College of Medicine. He is pursuing a career in pathology and has a special interest in hematopathology, cytopathology and blood bank/transfusion medicine. You can follow him on Twitter @Paraparacelsus.

Kamran M. Mirza, MD, PhD, MLS(ASCP)CM is an Assistant Professor of Pathology and Medical Education at Loyola University Health System. A past top 5 honoree in ASCP’s Forty Under 40, Dr. Mirza was named to The Pathologist’s Power List of 2018. Follow him on twitter @kmirza.