Microbiology Case Study: A 72 Year Old Woman with Persistent Cough

Clinical History

The patient is a 72 year old female who overall has been fairly healthy. She has struggled with a cough for several years. A CT scan in 2015 showed some tree-in-bud changes in the lungs potentially consistent with an atypical mycobacterial infection. She had a positive methacholine challenge test and was diagnosed with asthma. Her cough has not improved with inhaled asthma treatments. The cough has been persistent and is at times productive of small amounts of whitish sputum. She has not noted any progressive shortness of breath. Over the last several months she has tried trials of both nasal corticosteroids, and treatment with Prilosec for gastroesophageal reflux. Both of these trials had no effect on her cough. At the end of November 2018, a CT scan of the chest was consistent with an atypical mycobacterial infection.

In January 2019, she came back from a skiing trip. She tried to ski but was unable to because of shortness of breath; she came home on the third day prematurely. During this time, she developed increased cough, fevers and chills. An x-ray was obtained by her primary care provider, which showed a right lower lobe infiltrate, and was placed on levofloxacin for 5 days. After completing the antibiotic, she is still very fatigued and still coughing. She presented to her pulmonologist in March 2019. She denied any fevers, chills or chest pain. Her cough has continued with intermittent sputum production. Her appetite and weight have been stable, along with bladder and bowel habits.

The patient’s past medical history is significant for arthritis, cataracts, depression, polymyalgia rheumatica, and sciatic nerve pain. Her past surgical history is only a tonseillectomy in her childhood. Her social and family history is that she runs an educational travel business, is currently divorced, has never been a smoker, and has no family history significant for recurrent infections.

Laboratory Findings

Induced sputum samples were obtained and inoculated on a 7H9 bottle that was incubated and continuously monitored for growth. Eight days later, the 7H9 bottle flagged positive for growth. A gram stain showed branching gram positive bacilli. The Kinyoun acid-fast stain was negative, but a modified Kinyoun showed rare positive staining cells. The bottle was subcultured onto chocolate agar, 7H11 agar, buffered charcoal yeast extract (BCYE) agar, and LJ slants. Two days later, all plates except the 7H11 plate showed growth of white, dry, crinkled colonies as depicted in Image 1. A gram stain of the colonies showed branching gram positive bacilli as shown in Image 2. Again, the Kinyoun stain of the colonies was negative but the modified Kinyoun again highlighted cells as seen in Image 3. A representative colony was sent for identification to Mayo laboratories a day later. MALDI-TOF performed by Mayo Laboratories revealed the bacteria to be Rothia aeria. An attempt was made to set up sensitivities but the organism was not able to grow out on the test medium.

Image 1. Isolated bacteria culture on chocolate agar.
Image 2. Gram stain, 1000x.
Image 3. Modified AFB stain, 1000x.


Rothia aeria is a very rare pathogen with a current PubMed search yielding 20 references. It was first isolated from the MIR space station (1) and genomic sequencing was perform on the bacteria (2). It has been shown to be a normal oral flora (3), but also seems to be most associated with endocarditis. A few case reports have discussed sepsis, respiratory infections, and joint infections. Importantly, it has been documented to be confused with Nocardia species (4).


  1. Li, Y. et al. Rothia aeria sp. nov., Rhodococcus baikonurensis sp. nov., and Arthrobacter russicus sp. nov., isolated from air in the Russian space laboratory Mir. Int J Syst Evol Microbiol. 2004; 54(pt. 3): 827-835.
  2. Nambu, T. et al. Complete Genome Sequence of Rothia aeria Type strain JCM 11412, Isolated from Air in the Russian Space Laboratory Mir. Genome Announc. 2016 Dec 29; 4(6).
  3. von Graevenitz, A. et al. Coryneform bacteria in throat cultures of healthy individuals. J Clin Microbiol. 1998; 36: 2087-2088.
  4. Saraya, T. et al. Rothia aeria: a great mimicker of the Nocardia species. BMJ Case Rep. Published Online: November 18, 2014.

-Jeff Covington, MD, PhD is a 2nd year anatomic and clinical pathology resident at the University of Vermont Medical Center.

-Christi Wojewoda, MD, is the Director of Clinical Microbiology at the University of Vermont Medical Center and an Associate Professor at the University of Vermont.

Surgical Pathology Case Study: A 3 Year Old Male with a Suspicious Lesion on Imaging Following an Injury

Case History

The patient is a 3 year old male with no significant past medical history who presented to the ED with left lower extremity pain for 24 hours after falling while playing with family members. The patient’s mother was present at bedside providing the history, but was not present at the time of the fall. It is unclear how the patient injured his ankle, but family members noticed the child grabbing his ankle and suspected that he may have twisted it. After the fall, the patient was unable/unwilling to ambulate on the ankle. There is no history of fractures or cancer.

An x-ray and subsequent MRI were ordered of the ankle which demonstrated an expansile lytic lesion involving the metaphysis of the distal tibia measuring approximately 3.4 x 2.2 cm (Figure 1 and 2). The margins of this lesion are indistinct, and there is cortical irregularity at the anterior and lateral aspect of the distal metaphysis of the tibia, likely representing a pathologic fracture. The differential diagnosis includes infection, aneurysmal bone cyst, nonossifying fibroma, osteoblastoma and histiocytosis.

The patient and family then followed up with Orthopedics, who proceeded to perform a biopsy of the lytic lesion in order to determine the nature of the lesion. The results are below.

Figure 1. Xray of the distal tibia demonstrating the lesion.
Figure 2. MRI demonstrating the lytic lesion involving the metaphysis of the distal tibia.


Received fresh for intraoperative consultation is a 1.1 x 0.6 x 0.5 cm aggregate of white-tan soft tissue fragments. Half of the tissue fragments are frozen and read out as “spindle cell proliferation. Consideration of low-grade vasoformative lesion. Defer to permanent,” with 3 pathologists consulting on the diagnosis. The remainder of the tissue not submitted for frozen section, as well as the entirety of a second container from the same lesion, is submitted for routine processing.

On microscopy, the biopsies demonstrate a moderately cellular proliferation of fasciculated spindle cells in a collagenous to myxoid stroma. Nuclei are predominantly oval with variably fine to granular chromatin. Many cells have moderate amounts of tapering eosinophilic cytoplasm, resembling strap cells. Inflammatory cells and osteoclast-like giant cells are admixed (Figure 3 and 4). Immunohistochemical stains demonstrate lesional spindle cells to be positive for CD31, ERG, and FLI1. AE1/AE3 and CAM5.2 highlight rare lesional spindle cells. SMA stains some stellate spindle cells, favored to represent associated myofibroblasts. Desmin, MDM2, CDK4, ALK, and S100 are negative in plump lesional cells (Figure 5 and 6). Overall, the features are consistent with pseudomyogenic hemangioendothelioma, a rare vascular tumor. Although more commonly present in soft tissue, primary bone cases have been reported. These neoplasms have some risk for local recurrence, but only rarely distant metastasis. A portion of tissue was sent to the University of Nebraska Medical Center to evaluate for a characteristic gene rearrangement (SERPINE1-FOSB) that is present in at least a subset of pseudomyogenic hemangioendotheliomas. This was negative.

The lesion was then curettaged by the surgical team.The patient and his family had two follow up office visits with the Orthopedics department. The first one, a week after surgery, was unremarkable. The second visit, two weeks after surgery, was notable for the patient developing a cutaneous rash on both arms and chest. Due to literature citing that these tumors generally arise in the soft tissue, the clinician suggested that the patient and family follow up with pediatric dermatology to ensure that this new rash is not related to the pseudomyogenic hemangioendothelioma. Unfortunately due to insurance, the patient and family had to see a dermatologist at a different institution, and no further visits have taken place.

Figure 3. Photomicrograph of the strap-like cells with tapering eosinophilic cytoplasm , and osteoclast-like giant cells.
Figure 4. Higher power photomicrograph demonstrating the appearance of the strap-like cells with tapering eosinophilic cytoplasmFigure 4.


Pseudomyogenic hemangioendothelioma (PHE) is a rare vascular tumor that most commonly arises in the skin and soft tissues of the extremities. It is usually multifocal, appearing in multiple tissue planes, such as the mucosa, dermis, subcutis and skeletal muscle, in a variety of different anatomic sites. Although even less common, PHE can also involve bone (such as this case). PHE has a male predilection, typically appearing in the second to fourth decades of life. Of the most common symptoms that the patient presents with, pain appears to top the list, although it should be stated that only about half of the patients experience pain.

Grossly, skin and soft tissue PHE tumors appear firm, ill-defined and gray-white. When they involve bone, they appear as multiple discrete, pink-tan to dark brown hemorrhagic tumors with surrounding sclerosis, ranging from 0.1 to 6.5 cm in greatest dimension.

Histologically, PHE demonstrates plump spindle and rhabdomyoblast-like cells with densely eosinophilic cytoplasm that grows in sheets and fascicles. The cells can be mistaken as rhabdomyoblasts because of the eosinophilic cytoplasm that pushes the nucleus to the periphery of the cell. Immunohistochemical studies are very helpful in order to determine a diagnosis of PHE. AE1/AE3, ERG, FLI-1 and CD31 are positive, whereas CD34, desmin and S100 are negative. Karyotyping has revealed a fusion of genes SERPINE1-FOSB that corresponds to the recurrent translocation t(7;19)(q22;q13). In this case, the SERPINE1-FOSBgene rearrangement was negative, but could possibly be due to a variant fusion gene.

Making a histologic diagnosis can be difficult for a Pathologist, due to the wide variety of differential diagnoses that will need to be excluded first.

The differential diagnosis for a cutaneous tumor includes:

  • Cellular benign fibrous histiocytoma (lacks rhabdomyoblast-like cells and neutrophilic infiltrates, contains mitotic figures, and is negative for cytokeratin and CD31)
  • Spindle cell squamous cell carcinoma (usually in sun-damaged skin, with nuclear atypia and negative endothelial markers)
  • Epithelioid sarcoma (negative INI1, positive EMA and CD34, and a nodular architecture with central necrosis and more nuclear atypia)

The differential diagnosis for soft tissue tumors include:

  • Epithelioid sarcoma (see above)
  • Epithelioid hemangioendothelioma (usually intracytoplasmic vacuoles, positive CD34 and CAMTA1, and a t(1;3)(p36.3;q25) translocation resulting in WWTR1-CAMTA1 gene fusion)
  • Epithelioid angiosarcoma (vasoformative architecture with sheet-like pattern, nuclear atypia, high nuclear grade, frequent mitosis and irregular vascular channels)

 The differential diagnosis for bone tumors includes:

  • Epithelioid hemangioma (lacks rhabdomyoblast-like cells)
  • Giant cell tumor (lacks rhabdomyoblast-like cells and fascicles of spindle cells)
  • Osteoblastoma (lacks rhabdomyoblast-like cells and fascicles of spindle cells)

In a study by Inyang et al, when PHE involved bone, imaging would demonstrate multiple to innumerable discontinuous tumors throughout the affected bone, involving the cortex and/or medullary cavity of the epiphysis, metaphysis, or diaphysis. On x-ray and computed tomography, the lesions appeared as well circumscribed, lobulated and lytic, with a sclerotic rim on some of the lesions. On magnetic resonance imaging, T1-weighted images would appear dark, and T2-weighted images would appear hyperintense.

PHE has a tendency to recur locally, but rarely develops distant metastases. Since PHE presents as a multifocal disease and can be easily confused for a distant metastasis, care needs to be taken to ensure that a diagnosis of PHE is not overlooked.

Surgical ablation and excision is the standard treatment for a patient with PHE, with a few cases noted of patients being treated with radiotherapy and/or adjuvant chemotherapy, in addition to surgery. Everolimus and sirolimus have recently been found to be effective in cases of patient with PHE that had metastatic and relapsing multifocal PHE.

Figure 5. Immunohistochemical stains (part 1 of 2)
Figure 6. Immunohistochemical stains (part 2 of 2)


  1. Hornick JL, Fletcher CDM. “Pseudomyogenic Hemangioendothelioma: A Distinctive, Often Multicentric Tumor With Indolent Behavior.” Am J Surg Pathol. 2011; 35: 190201.
  2. Inyang A, et al. “Primary Pseudomyogenic Hemangioendothelioma of Bone.” Am J Surg Pathol. 2016; 40: 587598.
  3. Pradhan D. “Pseudomyogenic hemangioendothelioma of skin, bone and soft tissue; a clinicopathological, immunohistochemical, and fluorescence in situ hybridization study.” Hum Pathol. 2018; 71: 126134.
  4. Sugita S, Hirano H, Kikuchi N, et al. Diagnostic utility of FOSB immunohistochemistry in pseudomyogenic hemangioendothelioma and its histological mimics. Diagn Pathol. 2016;11(1):75. Published 2016 Aug 11. doi:10.1186/s13000-016-0530-2

-Cory Nash is a board certified Pathologists’ Assistant, specializing in surgical and gross pathology. He currently works as a Pathologists’ Assistant at the University of Chicago Medical Center. His job involves the macroscopic examination, dissection and tissue submission of surgical specimens, ranging from biopsies to multi-organ resections. Cory has a special interest in head and neck pathology, as well as bone and soft tissue pathology. Cory can be followed on twitter at @iplaywithorgans.

Microbiology Case Study: A 75 Year Old Female with Breast Erythema and Drainage

Clinical History

A 75 year old female with a past medical history of breast cancer presented to the Emergency Department with chills 3 weeks status-post bilateral breast reconstruction due to ruptured silicone breast implants. Her white blood cell count was 13,440/cmm and her temperature was 39.4ºC. Physical examination revealed erythema of the right breast incision and purulent drainage from the Jackson-Pratt (JP) drain. Two blood cultures were drawn and a specimen was collected from the JP drain fluid and sent for gram smear and culture.

Laboratory Findings

Blood cultures were negative for growth. Gram stain of the drain fluid was significant for many polymophonuclear neutrophils, however no bacteria were seen. Aerobic cultures grew gram positive cocci. Matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF) analysis identified Streptococcus gordonii. The patient was started on doxycycline and amoxicillin-clavulanate. Antibiotic susceptibility testing subsequently showed susceptibility to ceftriaxone and penicillin.

Image 1. Blood agar showing alpha-hemolytic colonies.
Image 2. Gram stain from media showing gram positive cocci.


Streptococcus gordonii is a gram positive, non-motile, facultative anaerobic cocci that is part of the Streptococcus sanguinis group of viridans group streptococci (VGS). It is a common oral bacteria that has been implicated in invasive infections such as endocarditis and septic arthritis. It is less frequently a cause of soft-tissue infections such as orbital cellulitis, osteomyelitis, and subcutaneous abscesses. There are case reports of joint prosthesis infections, however breast implant infections have not been reported. Breast implant infections are most commonly caused by Staphylococcus aureus, Pseudomonas aeruginosa, and Staphylococcus epidermidis. There are reports of different VGS species causing breast implant infections. As the bacteria primarily resides in the mouth, infections are usually caused by oral trauma. Although symptoms may often be minor, in cases caused by VGS, systemic symptoms can occur including a toxic shock-like syndrome. In these cases there is a case fatality rate as high as 80%. S. gordonii has been reported as susceptible to clindamycin, ceftriaxone, erythromycin, and levofloxacin. Prompt treatment is important to prevent progression to systemic illness and mortality.


  1. Seng P, Bayle, S, Alliez, A, et al. The microbial epidemiology of breast implant infections in a regional referral centre for plastic and reconstructive surgery in the south of France. Int J Infect Dis. June 2015;35:62-66.
  2. Fenelon C, Galbraith JG, Dalton DM, Masterson E. Streptococcus gordonii—a rare cause of prosthetic joint infection in a total hip replacement. J Surg Case Rep. 2017 Jan;1:235.
  3. Liao CY, Su KJ, Lin CH, et al. Planta purpura as the initial presentation of viridans streptococcal shock syndrome secondary to Streptococcus gordonii bacteremia. Can J Infect Dis Med Microbiol. 2016:946385.
  4. Dadon Z, Cohen A, Szterenlicht YM, et al. Spondylodiskitis and endocarditis due to Streptococcus gordonii. Ann Clin Microbiol Antimicrob. 2017:16:68.
  5. Krantz AM, Ratnaraj F, Velagapudi M et al. Streptococcus gordonii empyema: a case report and review of empyema. Cureus. 2017 Apr;9(4):e1159.

-Jonathan Wilcock, MD is a 1st year anatomic and clinical pathology resident at the University of Vermont Medical Center.

-Christi Wojewoda, MD, is the Director of Clinical Microbiology at the University of Vermont Medical Center and an Associate Professor at the University of Vermont.

Microbiology Case Study: a 49 Year Old Man with Chest Pain and Shortness of Breath

Case History

A 49 year old male presented to the emergency department (ED) with complaints of chest pain, shortness of breath, and chills for the past two weeks. He describes the pain as sharp and located on the left side of his chest. Past medical history is non-contributory, except for current IV drug use. His temperature was 97.7°F, blood pressure 141/63, heart rate 87, respirations 18 with an oxygen saturation of 91-93% on room air. On physical exam, a regular rate & rhythm with no murmur or regurgitation was noted and lungs showed fine bilateral crackles. His white blood cell count was increased at 22.1 TH/cm2 and troponin I was also elevated at 0.19 ng/ml. Blood cultures were collected and the patient was started on ceftaroline and piperacillin tazobactam for presumed infective endocarditis. He was transferred to the medical intensive care unit and intubated due to respiratory distress. An echocardiogram revealed a large mobile vegetation on the aortic valve with severe insufficiency and a vegetation & thickening of the mitral valve with severe regurgitation.

Laboratory Identification

Image 1. Gram stain showed gram positive cocci arranged in pairs and chains (1000x oil immersion).
Image 2. Small, gray, non-hemolytic colonies grew on blood and chocolate agar after 48 hours of incubation at 35°C in 5% CO2. There was no growth on MacConkey agar.
Image 3. Portions of valve leaflets showing acute neutrophilic fibrinous exudate (H&E, 300x).
Image 4. Special stain highlighting numerous bacterial cocci (GMS, 300x).

Blood cultures were positive within 24 hours of collection and gram positive cocci arranged in pairs and chains were noted (Image 1). Enterococcus spp., vancomycin resistance not detected was reported by polymerase chain reaction (PCR). Small, gray, non-hemolytic colonies grew after 2 days of incubation (Image 2). MALDI-TOF mass spectrometry identified the isolate as Enterococcus faecalis.


Enterococcus spp. are gram positive, catalase negative cocci that are arranged in pairs & chains and are facultative anaerobes. Enterococcus spp. are widespread in nature and a component of the normal flora of the gastrointestinal tract and less commonly found in the oral cavity and on the skin. Commonly, Enterococcus spp. are opportunistic pathogens and cause infections of the urinary tract, intraabdominal cavity, surgical sites, bacteremia, and infective endocarditis.   

In the microbiology laboratory, Enterococcus spp. grow readily on non-selective media and are usually alpha-hemolytic or non-hemolytic on blood agar. The two main species, E. faecalis and E. faecium, will grow in 6.5% NaCl, hydrolyze esculin in the presence of bile salts, and are positive for both leucine aminopeptidase (LAP) and L-pyrrolidonyl-beta-naphthylamide (PYR). Biochemically, arabinose utilization serves as a useful indicator to distinguish E. faecalis (negative) and E. faecium (positive). A variety of identification systems are able to identify the great majority of Enterococcus spp. to a species level.

Ampicillin or vancomycin are acceptable treatment options for Enterococcal infections if found to be susceptible by antibiotic testing. It is important to note, Enterococcus spp. are intrinsically resistant to cephalosporins, aminoglycosides, trimethoprim-sulfamethoxazole, and clindamycin. For serious infections, including infective endocarditis, it is recommended to treat with a cell wall active agent such as ampicillin and an aminoglycoside (gentamicin or streptomycin) to create a synergistic bactericidal effect. Emergence of E. faecium acquired vancomycin resistance (VanA/VanB) is increasing and more board spectrum agents such as daptomycin and linezolid are necessary to effectively treat these infections.     In the case of our patient, upon identification of E. faecalis from multiple blood cultures, his antibiotics were switched to IV ampicillin and gentamicin. He underwent valve replacement surgery and both the aortic and mitral valves grew E.faecalis as well and showed numerous bacterial cocci on histology (Images 3 & 4). He completed a six week course of ampicillin and gentamicin and was discharged home in good condition.

-Hansini Laharwani, MD is a first year Anatomic and Clinical Pathology resident at the University of Mississippi Medical Center. 

-Lisa Stempak, MD, is an Assistant Professor of Pathology at the University of Mississippi Medical Center in Jackson, MS. She is certified by the American Board of Pathology in Anatomic and Clinical Pathology as well as Medical Microbiology. She is the Director of Clinical Pathology as well as the Microbiology and Serology Laboratories. Her interests include infectious disease histology, process and quality improvement, and resident education.

Microbiology Case Study: A 70 Year Old Male with a Decubitus Ulcer

Clinical History

A 70 year old male with a history of multiple system atrophy and left hip fracture presented to his primary care physician after being found by his home health nurse to have a sacral decubitus ulcer. Physical examination revealed an afebrile immobile patient with a 3.0 cm stage III ulcer over the sacrum with purulent exudate. Tissue was obtained and sent to our laboratory for Gram stain and culture.

Laboratory Findings

Gram stain was significant for many polymorphonuclear neutrophils and mixed gram positive and gram negative organisms. Blood and chocolate plates grew mixed organisms with a predominant gram positive coccobacillus. Matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF) identified this organism as Trueperella bernardiae.

Image 1. Gram stain from tissue showing mixed gram positive and gram negative organisms.
Image 2. Blood agar showing non-hemolytic white colonies.


Trueperella bernardiae is a nonspore-forming, facultatively anaerobic, gram-positive coccobacillus. It was previously categorized within the Actinomyces and Arcanobacterium genera. It is classically associated with pig farming. It is often considered to be a contaminant or normal flora, however, it has been reported as a cause of bone and soft tissue infections. Highly invasive diseases are rare. The incidence of infection may have been underreported previously due to the difficulty to culture and identify it from normal flora prior to the advent of MALDI-TOF. Antibiotic sensitivity data is limited, however, there are reports of susceptibility to beta-lactams, clindamycin, tetracycline, and vancomycin. Minimum inhibitory concentration interpretation is often based on data from bacteria of the Corynebacterium.


  1. Rattes ALR, Araujo MR, Federico MP, et al. Trueperella bernardiae: first report of wound infection post laparoscopic surgery. Clin Case Rep. 2016 Aug;4(8):812-815.
  2. Lawrence CHD, Waseem S, Newsholme W, Klein JL. Trueperella bernardiae: an unusual cause of septic thrombophlebitis in an injection drug user. New Microbes New Infect. 2018 Nov;26:89-91.
  3. Cobo F, Rodriquez-Granger J, Sampedro A, et al. Two Rare Cases of Wound Infections Caused by Trueperella bernardiae. Jpn J Infect Dis. 2017;70:682-684.
  4. Gowe I, Parsons C, Best M, et al. Successful treatment of olecranon bursitis caused by Trueperella bernardiae: importance of environmental exposure and pathogen identification. Case Reports in Infectious Diseases. 2018;5353085.

-Jonathan Wilcock, MD is a 1st year anatomic and clinical pathology resident at the University of Vermont Medical Center.

-Christi Wojewoda, MD, is the Director of Clinical Microbiology at the University of Vermont Medical Center and an Associate Professor at the University of Vermont.

Microbiology Case Study: A 90 Year Old Male with Acute Appendicitis

Case History

A 90 year old male is transferred from his nursing care facility to the hospital for management of acute appendicitis. He had acute onset of right lower quadrant abdominal pain the morning prior to admission with fevers, rigors and drenching sweats. Imaging showed ruptured appendicitis with a fecalith surrounded by small pockets of fluid. His past medical history included dementia, heart disease, hyperlipidemia, hypertension, and glucose intolerance. He denied having any prosthetic joints or valves. Blood was obtained for microbiological analysis.

Laboratory Identification

Blood culture bottles flagged positive. Gram stain of the blood culture bottles showed medium to long gram negative bacilli (Image 1). The blood culture media was plated on blood, chocolate, and MacConkey agar. Aerobically, yellow colonies grew on the blood and chocolate agar. The yellow colonies turned red when exposed to 10% KOH (Image 2). Definitive diagnosis of Chryseobacterium gleum was obtained by MALDI-TOF.

Image 1. Gram stain from the blood culture bottle shows gram negative bacilli.
Image 2. Growth of the organism on chocolate agar with addition of 10% KOH solution (circled in black).


Chryseobacterium gleum is a gram negative bacillus. They form yellow colonies that grow on blood and chocolate agar. They rarely grow on MacConkey agar and are non-fermenters when they do grow. Species of Chryseobacterium will turn red with addition of 20% KOH due to a pigment protein called flexirubin. Interestingly, our lab had only 10% KOH and the colonies turned red with this as well. Other key biochemical and physiologic characteristics of Chryseobacterium include being indole and oxidase positive and they are non-motile.

Chryseobacterium species are found in the environment and are usually not part of normal flora, therefore infection requires exposure of the bug to a debilitated patient in order to colonize the respiratory tract. However, infection of other body sites that may or may not have preceded respiratory tract colonization have been reported. These organisms can survive in chlorinated tap water. They are an emerging cause of hospital associated infections. No virulence factors have been studied. Risk factors for infection include immunosuppression, trauma, surgery, burns, foreign body implants and infused fluids. Of note, the patient was thought to obtain his Chryseobacterium bacteremia from his ruptured appendicitis.

For therapy, there are no definitive guidelines due to lack of understanding of resistance mechanisms. These antibiotics have been reported to have potential activity: Ciprofloxacin, rifampin, clindamycin, trimethoprim/sulfamethoxazole and vancomycin (reportedly for C. indologenes). Our patient was given Piperacillin/tazobactam, Ceftriaxone and metronidazole for two days, Cefepime for one day, Vancomycin for a day. Infectious disease recommended continuing piperacillin/tazobactam and starting trimethoprim/sulfamethoxazole and discontinuing vancomycin.

Antimicrobial susceptibility testing was performed and showed resistance to meropenem, aztreonam, gentamicin, and tobramycin. The organism was susceptible to piperacillin/tazobactam and trimethoprim/sulfamethoxazole.


  1. Tille P. Bailey & Scott’s Diagnostic Microbiology. Fourteenth Edition. Elsevier; 2017.
  2. Murray P. Medical Microbiology. Seventh Edition. Elsevier; 2013.
  3. Jain V, Hussain NAFA, Siddiqui T, Sahu C, Ghar M, Prasad KN. Simultaneous isolation of Chryseobacterium gleum from bloodstream and respiratory tract: first case report from India. JMM Case Rep. 2017;4(10):e005122. Published 2017 Oct 16. doi:10.1099/jmmcr.0.005122

-Angela Theiss, MD is a 3rd year anatomic and clinical pathology resident at the University of Vermont Medical Center.

-Christi Wojewoda, MD, is the Director of Clinical Microbiology at the University of Vermont Medical Center and an Associate Professor at the University of Vermont.

Hematopathology Case Study: A 71 Year Old Man with a History of Multiple Myeloma

Case History

A 71 year old man with a history of multiple myeloma presented with urinary incontinence and confusion and was found to have hyperkalemia with renal failure. Imaging showed extensive inguinal lymphadenopathy with concern for new lymphoma.

Excisional Lymph Node Biopsy

H&E 40x


Sections show an enlarged lymph node with complete effacement of the normal lymph node architecture by sheets of medium and large plasmablastic cells. The cells have round nuclear contours, large prominent nucleoli and moderate amounts of amphophilic cytoplasm. Frequent apoptotic cells and scattered mitoses are seen.

Immunohistochemical stains show that the neoplastic cells are immunoreactive for CD138, CD38, CD19 (dim) and MUM1. They are negative for CD20, which highlights only small admixed B-cells. The cells are kappa restricted by kappa and lambda immunostain. The Ki-67 proliferation index is greater than 90%.

Taken together, the morphologic and immunophenotypic features are of a high grade plasmablastic neoplasm. The differential diagnosis includes plasmablastic myeloma and a plasmablastic lymphoma. Given the patient’s history of a kappa restricted plasma cell dyscrasia, plasmablastic myeloma is favored.


Multiple myeloma is a neoplasm of clonal plasma cells that accounts for 10% of all hematologic malignancies. It is most commonly seen in adult and elderly patients with a male predominance. Plasma cells are generally characterized by the presence of a “clockface” nuclei and distinct perinuclear Hof or clearing of the cytoplasm containing a large number of Golgi bodies. The morphology of plasma cell tumors can range from small mature plasma cells to anaplastic or plasmablastic morphology. In this case, the cells showed plasmablastic (PB) morphology, which is characterized by a large nucleus, large nucleolus, fine reticular nuclear chromatin pattern, lack of nuclear Hof and less abundant cytoplasm than typical plasma cells.1

The differential diagnosis for cases with this morphology primarily includes PB lymphoma and PB myeloma with extramedullary involvement. PB lymphoma is seen more commonly in HIV positive patients or patients with other causes of immunodeficiency. It typically occurs in adults and has a male predominance. The tumor generally presents outside of nodes and is most frequently seen in the oral cavity/jaw. Patients tend to present with advanced stage and bone marrow involvement. While PB lymphoma is categorized as a distinct subtype of diffuse large B-cell lymphoma, PB myeloma is considered an atypical morphologic variant of multiple myeloma and is treated with therapy geared towards plasma cell neoplasms. 2

Making the distinction between these entities is difficult due to similarities in morphology and immunophenotype. Ultimately, the diagnosis is generally made based on the clinical context. In one series of “plasmablastic” neoplasms by Ahn, et. al., 6 out of 11 cases were called PB lymphoma, 2 out of 11 were called multiple myeloma and 3 were called indeterminate. Among the PB lymphoma patients, 4 were either HIV positive or had a history of immunosuppression. All 6 cases were positive for CD138 and negative for CD20 with EBV in situ hybridization positivity in 3 out of 6 cases. The multiple myeloma cases had evidence of end organ damage without lymphadenopathy. One indeterminate case had peritoneal nodules, lytic lesions and an EBV positive neoplasm in the bone marrow, which precluded a definitive diagnosis. 3

The immunophenotypic pattern seen in this case is typical of these neoplasms and is characterized by the expression of plasma cell antigens (CD138, CD38, MUM1) with either weak or negative expression of B-cell antigens (CD20). A study by Vega et. al. looked at the immunophenotypic profiles in nine cases of PB lymphoma and seven cases of PB myeloma. They found that the profiles were nearly identical.  All cases were positive for MUM1/IRF4, CD138 and CD38 and negative for CD20, consistent with a plasma cell immunophenotype. PAX5 and BCL6 were weakly positive in 2/9 and 1/5 PB lymphomas and were negative in all PB myelomas. A high Ki-67, overexpression of P53 and loss of p16 and p27 were present in both tumors. There was no evidence of HHV8 detected in either neoplasm. The presence of EBV-encoded RNA, was seen in all PB lymphoma cases tested and negative in all plasma cell myeloma cases. This was found to be statistically significant. 4

Unfortunately, both PB lymphoma and PB myeloma are aggressive high grade neoplasms with a poor prognosis. A study conducted by Greipp et. al. assessed the prognostic significance of plasmablastic morphology in a cohort of patients from the Eastern Cooperative Oncology Group Myeloma Trial E9486. They looked at bone marrow aspirates from 453 newly diagnosed multiple myeloma cases in a 5 year period. Of the 453 aspirates, 8.2% were classified as PB morphology.  The overall survival of patients with PB morphology was significantly shorter than patients with non-PB morphology with a median of 1.9 years compared to 3.7 years. There did not appear to be a relationship between PB morphology to other clinical or laboratory features such as age, sex, bone lesions or type of M-protein. 5


  1. M Srija, P Zachariah, V Unni, et. al. Plasmablastic myeloma presenting as rapidly progressive renal failure in a young adult, Indian Journal of Nephrology, Volume 24(1): 2014, Page 41-44.
  2. JJ Castillo, M Bibas, RN Miranda, The biology and treatment of plasmablastic lymphoma, Blood, Volume 125, 2015, Page 2323-2330.
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Chelsea Marcus, MD is a Hematopathology Fellow at Beth Israel Deaconess Medical Center in Boston, MA. She has a particular interest in High-grade B-Cell lymphomas and the genetic alterations of these lymphomas.