Extraenteric Malignant Gastrointestinal Neuroectodermal Tumor-A Clinicopathologic and Molecular Genetic Study of 11 Cases.

Malignant gastrointestinal neuroectodermal tumors (MGNETs), also known as "gastrointestinal clear cell sarcoma-like tumors", are very rare, aggressive sarcomas characterized by enteric location, distinctive pathologic features, and EWSR1/FUS::ATF1/CREB1 fusions. Despite identical genetics, the clinicopathologic features of MGNET are otherwise quite different from those of clear cell sarcoma of soft parts. Only exceptional extraenteric MGNET (E-MGNET) has been reported. We report a series of 11 E-MGNETs, the largest to date. Cases diagnosed with MGNET and occurring in nonintestinal locations were retrieved. A clinical follow-up was obtained. The tumors occurred in 3 men and 8 women (range, 14-70 years of age; median, 33 years) and involved the soft tissues of the neck (3), shoulder (1), buttock (2), orbit (1), tongue/parapharyngeal space (1), urinary bladder (1), and falciform ligament/liver (1). Tumors showed morphologic features of enteric MGNET (small, relatively uniform, round to ovoid cells with round, regular nuclei containing small nucleoli growing in multinodular and vaguely lobular patterns, with solid, pseudoalveolar, and pseudopapillary architecture). Immunohistochemical results were S100 protein (11/11), SOX10 (11/11), synaptophysin (3/10), CD56 (7/9), CD117 (3/9), DOG1 (0/4), ALK (4/8), chromogranin A (0/10), HMB-45 (0/11), Melan-A (0/11), tyrosinase (0/4), and MiTF (0/11). Next-generation sequencing results were EWSR1::ATF1 (7 cases), EWSR1::CREB1 (3 cases), and EWSR1::PBX1 (1 case). The EWSR1::PBX1-positive tumor was similar to other cases, including osteoclast-like giant cells, and negative for myoepithelial markers. A clinical follow-up (range, 10-70 months; median, 34 months) showed 4 patients dead of disease (10.5, 12, 25, and 64 months after diagnosis), 1 patient alive with extensive metastases (43 months after diagnosis), 1 patient alive with persistent local disease (11 months after diagnosis), and 4 alive without disease (10, 47, 53, and 70 months after diagnosis). One case is too recent for the follow-up. The clinicopathologic and molecular genetic features of rare E-MGNET are essentially identical to those occurring in intestinal locations. Otherwise, typical E-MGNET may harbor EWSR1::PBX1, a finding previously unreported in this tumor type. As in enteric locations, the behavior of E-MGNET is aggressive, with metastases and/or death from disease in at least 50% of patients. E-MGNET should be distinguished from clear cell sarcoma of soft parts and other tumors with similar fusions. ALK expression appears to be a common feature of tumors harboring EWSR1/FUS::ATF1/CREB1 fusion but is unlikely to predict the therapeutic response to ALK inhibition. Future advances in our understanding of these unusual tumors will hopefully lead to improved nomenclature.

Mucormycosis Causing Ludwig Angina: A Unique Presentation.

Mucormycosis is a rare fungal infection with a yearly incidence of 1.7 cases per million in the United States. It usually occurs in patients with metabolic abnormalities or who are immunocompromised with prolonged neutropenia. However, it can also occur in patients without any underlying disease process. The treatment of choice is surgical debridement of necrotic tissue and systemic antifungal therapy, including amphotericin B. A dilemma for the surgeon when faced with head and neck mucormycosis is the morbidity of surgical debridement from both a functional and cosmetic standpoint. There have been multiple case reports of a form of cutaneous mucormycosis in the head and neck involving the oral mucosa and the mandible, but no reports in the literature of a fungal infection causing Ludwig angina. This report describes one such case. The morbid clinical implications of mucormycosis causing Ludwig angina become apparent when considering the defect caused by adequate surgical debridement.

Histone hypoacetylation-activated genes are repressed by acetyl-CoA- and chromatin-mediated mechanism.

Transcriptional activation is typically associated with increased acetylation of promoter histones. However, this paradigm does not apply to transcriptional activation of all genes. In this study we have characterized a group of genes that are repressed by histone acetylation. These histone hypoacetylation-activated genes (HHAAG) are normally repressed during exponential growth, when the cellular level of acetyl-CoA is high and global histone acetylation is also high. The HHAAG are induced during diauxic shift, when the levels of acetyl-CoA and global histone acetylation decrease. The histone hypoacetylation-induced activation of HHAAG is independent of Msn2/Msn4. The repression of HSP12, one of the HHAAG, is associated with well-defined nucleosomal structure in the promoter region, while histone hypoacetylation-induced activation correlates with delocalization of positioned nucleosomes or with reduced nucleosome occupancy. Correspondingly, unlike the majority of yeast genes, HHAAG are transcriptionally upregulated when expression of histone genes is reduced. Taken together, these results suggest a model in which histone acetylation is required for proper positioning of promoter nucleosomes and repression of HHAAG.

Yeast phospholipase C is required for normal acetyl-CoA homeostasis and global histone acetylation.

Phospholipase C (Plc1p) is required for the initial step of inositol polyphosphate (InsP) synthesis, and yeast cells with deletion of the PLC1 gene are completely devoid of any InsPs and display aberrations in transcriptional regulation. Here we show that Plc1p is required for a normal level of histone acetylation; plc1Δ cells that do not synthesize any InsPs display decreased acetylation of bulk histones and global hypoacetylation of chromatin histones. In accordance with the role of Plc1p in supporting histone acetylation, plc1Δ mutation is synthetically lethal with mutations in several subunits of SAGA and NuA4 histone acetyltransferase (HAT) complexes. Conversely, the growth rate, sensitivity to multiple stresses, and the transcriptional defects of plc1Δ cells are partially suppressed by deletion of histone deacetylase HDA1. The histone hypoacetylation in plc1Δ cells is due to the defect in degradation of repressor Mth1p, and consequently lower expression of HXT genes and reduced conversion of glucose to acetyl-CoA, a substrate for HATs. The histone acetylation and transcriptional defects can be partially suppressed and the overall fitness improved in plc1Δ cells by increasing the cellular concentration of acetyl-CoA. Together, our data indicate that Plc1p and InsPs are required for normal acetyl-CoA homeostasis, which, in turn, regulates global histone acetylation.

Recurrent Zenker's Traction Diverticulum After Cervical Spine Surgery: Lessons Learned.

This is a report of our institutional experience regarding pharyngoesophageal diverticula formation following anterior cervical spine surgery (ACSS). It is a retrospective chart review of institutional patients from January 2008 to May 2020. Patients at our institution were identified by our two senior authors. Inclusion criteria included patients > 18 years old, a history of prior ACSS, and a confirmed diagnosis of pharyngoesophageal diverticulum with radiographic imaging. Three patients were identified to have an ACSS-related diverticulum. The case presentations describe surgical management and the subsequent postoperative course. One patient had a particularly complicated course with recurrent diverticulum formation despite prior excision. The patient continued to have dense scar tissue adhering the posterior esophageal wall to the nearby cervical spine plates, despite prior excision and rotation of nearby tissue. This difficult case demonstrated the need for an open and aggressive approach. ACSS-related diverticula that form in patients with a history of prior anterior cervical spine surgery appear to be a form of traction diverticulum due to dense scar tissue that adheres the pharyngoesophageal mucosa to the adjacent cervical spinal plate. This type of diverticulum differs from Zenker's diverticulum. Surgical management is recommended to resolve patients' symptoms.

American Society of Cytopathology Telecytology validation recommendations for rapid on-site evaluation (ROSE).

Telecytology has multiple applications, including rapid onsite evaluation (ROSE) of fine-needle aspiration (FNA) specimens. It can enhance cytopathology practice by increasing productivity, reducing costs, and providing subspecialty expertise in areas with limited access to a cytopathologist. However, there are currently no specific validation guidelines to ensure safe practice and compliance with regulations. This initiative, promoted by the American Society of Cytopathology (ASC), intends to propose recommendations for telecytology implementation. These recommendations propose that the validation process should include testing of all hardware and software, both separately and as a whole; training of all individuals who will participate in telecytology with regular competency evaluations; a structured approach using retrospective slides with defined diagnoses for validation and prospective cases for verification and quality assurance. Telecytology processes must be integrated into the laboratory's quality management system and benchmarks for discrepancy rates between preliminary and final diagnoses should be established and monitored. Special attention should be paid to minimize discrepancies that downgrade malignant cases to benign (false positive on telecytology). Currently, billing and reimbursement codes for telecytology are not yet available. Once, they are, recommendation of the appropriate usage of these codes would be a part of the recommendations. These proposed guidelines are intended to be a resource for laboratories that are considering implementing telecytology. These recommendations can help to ensure the safe and effective use of telecytology and maximize its benefits for patients.

Relationship Between Worst Pattern of Invasion and Extranodal Extension in Oral Tongue Squamous Cell Carcinomas.

BACKGROUND: Oral tongue squamous cell carcinoma (OTSCC) is a common malignancy of the oral cavity with poor survival rates. The aim of this project is to investigate the relationship between certain histopathological factors such as Worst Pattern of Invasion (WPOI) and Extranodal Extension (ENE) in patients with oral tongue squamous cell carcinoma (OTSCC) who underwent surgical resection at Loyola University Medical Center. METHODS: This was a retrospective cohort study at a tertiary care academic medical center. All patients that underwent primary surgical resection of OTSCC between 1/1/2015 and 1/1/2022 were reviewed. Patients were identified using the Cerner CoPath Laboratory Information System. RESULTS: A total of 82 patients met inclusion criteria and were included in the study. Higher grades of WPOI (WPOI 5) were not significantly associated with the presence of ENE in our study (P = 0.82), regardless of the presence of major or minor ENE. WPOI 5 was associated with a higher incidence of local recurrence (P = 0.011). CONCLUSIONS: Higher grades of WPOI were not found to correlate with the presence of ENE, a common histopathological factor that is used as an important prognostic indicator in OTSCC. It is important for clinicians to consider these factors separately when determining whether a patient is high-risk and would benefit from aggressive multimodal treatment.

Selinexor in Combination with Decitabine Attenuates Ovarian Cancer in Mice.

BACKGROUND: High-grade serous ovarian cancer is a lethal gynecologic disease. Conventional therapies, such as platinum-based chemotherapy, are rendered inadequate for disease management as most advanced disease patients develop resistance to this therapy and soon relapse, leading to poor prognosis. Novel immunotherapy and targeted therapy are currently under investigation as treatment options for ovarian cancer, but so far with little success. Epigenetic changes, such as aberrant DNA methylation, have been reported in resistance to platinum-based therapy. Decitabine is a hypomethylating agent which is effective against platinum-resistant disease and also exhibits several anti-tumor immune functions. Selinexor is a selective inhibitor of nuclear protein export. It restored platinum sensitivity in patient-derived ovarian cancer cell lines and is currently in clinical trials for the treatment of platinum-resistant ovarian cancer. We hypothesized that these two agents used in combination could elicit more potent anti-tumor immune responses in vivo than either agent used alone. METHODS: These studies were designed to investigate the efficacy of these two agents used in combination to treat ovarian cancer by assessing murine models for changes in disease pathology and in anti-tumor responses. RESULTS: Decitabine priming followed by selinexor treatment significantly limited ascites formation and tumor size. This combination of agents also promoted T cell effector function as measured by granzyme B secretion. Treatment of mice with decitabine and selinexor led to the significant release of a broader range of macrophage and T cell cytokines and chemokines above control PBS and vehicle and above decitabine or selinexor treatment alone. CONCLUSIONS: These results reveal crucial information for the design of clinical trials which may advance therapy outcomes in ovarian cancer.

Telecytology validation: is there a recipe for everybody?

INTRODUCTION: Telecytology offers a suitable solution to the cost and time efficiency questions on rapid onsite evaluation (ROSE). An increasing number of institutions are adopting new telecytology systems to meet the increasing ROSE requests, although there is no agreement on the details of how a telecytology validation study needs to be conducted. We propose a standardized approach for telecytology validation studies that could be done in a variety of practices. MATERIALS AND METHODS: Consecutive cases from 6 months prior were chosen to reflect a case mix comparable to real life. A fellow assessed the slides at the ROSE site while 6 cytopathology faculty convened in a conference room with a television screen, and noted the adequacy, diagnostic category, and specific diagnoses. All participants were blinded to the original adequacy assessment and final diagnoses. For each case, evaluation time and the slides counts were noted. RESULTS: Fine-needle aspiration specimens from 52 patients were included in the study. Of these, 13 cases were used in the first "test" session. The adequacy concordance rates ranged between 92.3% and 100%, with an overall concordance rate of 94.8%. The diagnostic category concordance rates ranged between 90.3% and 95.5%, with an overall concordance rate of 91.9%. The specific diagnosis concordance rates ranged between 84.6% and 92.9%, with an overall concordance rate of 88.1%. CONCLUSIONS: Validation of telecytology requires a standardized approach just like any other new technology. In this study, we propose an efficient and accurate method for cytopathology departments of various case volumes to conduct telecytology validation studies.

Five-year retrospective review in gynecologic cytopathology: is it time to amend?

INTRODUCTION: According to the Clinical Laboratory Improvement Amendments 1988 regulations, 5-year retrospective review (5YRR) of normal Papanicolaou tests in patients with a newly diagnosed high grade squamous intraepithelial lesion or above (HSIL+) is mandatory. Since this mandate has been in place, a multitude of changes have taken place in the screening and management guidelines of cervical cancer. The aim of this study is to assess the role of this mandate in our laboratory and to investigate the lessons learned. MATERIAL AND METHODS: The cytopathology electronic database and institutional quality assurance records at Loyola University Medical Center were searched from January 2009 to December 2019 to identify all Papanicolaou tests diagnosed as new "HSIL and above" (HSIL+). Major discrepancy (2+) was defined as initial negative diagnosis changed to HSIL+. RESULTS: A total of 153,083 Papanicolaou tests were performed during this period; out of these, 1452 (0.94%) were diagnosed as HSIL+. A total of 695 HSIL+ Papanicolaou tests had a negative prior Papanicolaou and in 615 of 695 there was agreement with the initial negative diagnosis. In 61 Papanicolaou tests, the initial diagnosis was changed from negative and they were reclassified on review as 3 HSIL, 9 ASC-H, 7 AGC, and 42 ASCUS or LSIL. Major discrepancy rate was calculated as 3 of 695 (0.43%). None required an amended report. CONCLUSIONS: It is important to revisit the 5YRR as a method of implementing the quality indicators in gynecologic cytology so that the process retains its value without overburdening cytology laboratories and personnel.

Intermixed medullary and papillary thyroid cancer in a patient with renal cell carcinoma.

SUMMARY: We report a rare case of concurrent medullary thyroid cancer (MTC) and papillary thyroid cancer (PTC) with intermixed disease in several of the lymph node (LN) metastases in a patient who was subsequently diagnosed with clear cell renal cell carcinoma (RCC). A 56 year old female presented with dysphagia and was found to have a left thyroid nodule and left superior cervical LN with suspicious sonographic features. Fine needle aspiration biopsy (FNAB) demonstrated PTC in the left thyroid nodule and MTC in the left cervical LN. Histopathology demonstrated multifocal PTC with 3/21 LNs positive for metastatic PTC. One LN in the left lateral neck dissection exhibited features of both MTC and PTC within the same node. In the right lobe, a 0.3 cm focus of MTC with extra-thyroidal extension was noted. Given persistent calcitonin elevation, a follow-up ultrasound displayed an abnormal left level 4 LN. FNAB showed features of both PTC and MTC on the cytopathology itself. The patient underwent repeat central and left radical neck dissection with 3/6 LNs positive for PTC in the central neck and 2/6 LNs positive for intermixed PTC and MTC in the left neck. There was no evidence of distant metastases on computed tomography and whole body scintigraphy, however a 1.9 x 2.5 cm enhancing mass within the right inter-polar kidney was discovered. This lesion was highly suspicious for RCC. Surgical pathology revealed a 2.5 cm clear cell RCC, Fuhrman grade 2/4, with negative surgical margins. She continues to be observed with stable imaging of her triple malignancies. LEARNING POINTS: Mixed medullary-papillary thyroid neoplasm is characterized by the presence of morphological and immunohistochemical features of both medullary and papillary thyroid cancers within the same lesion. Simultaneous occurrence of these carcinomas has been previously reported, but a mixed disease within the same lymph node is an infrequent phenomenon. Prognosis of mixed medullary-papillary thyroid carcinomas is determined by the medullary component. Therefore, when PTC and MTC occur concurrently, the priority should be given to the management of MTC, which involves total thyroidectomy and central lymph node dissection. Patients with thyroid cancer, predominantly PTC, have shown higher than expected rates of RCC. To our knowledge, this is the first report describing the combination of MTC, PTC, and RCC in a single patient.

The utilization and utility of immunostains in body fluid cytology.

BACKGROUND: Body fluid cytology (BFC) is an important tool in the diagnosis and staging of malignancy and is aided by the judicious use of immunohistochemistry (IHC). The aim of this study was to determine the usage rates of IHC stains in BFC, their type and indications, and their diagnostic impact. We also attempted to estimate the optimal rate of IHC use in BFC by comparing the entire laboratory's and each individual cytopathologist's IHC use rates with their respective indeterminate and malignant diagnosis rates. METHODS: We conducted a retrospective study of IHC stain use in BFC during a 5.5-year interval (2013-2018) and determined the laboratory's and each individual cytopathologist's IHC usage patterns according to the final diagnosis, site, and indications for their use. RESULTS: A total of 477 out of 4144 (11.5%) BFC cases had 2128 individual immunostains performed, with an average of 4.5 immunostains per case. Individual cytopathologists used IHC stains on 6.7% to 22% of their BFC cases. Pathologists with higher rates of IHC stain use than the laboratory's mean were less experienced and had higher rates of indeterminate but not of malignant diagnoses. The most common indication for the use of IHC stains was differentiating mesothelial from malignant cells. MOC31, calretinin, Ber-EP4, CD68, and D2-40 were the most commonly used of the 67 different IHC stains used in BFC. CONCLUSIONS: The laboratory's mean may represent the optimal IHC use rate, as higher IHC use rates did not lead to more diagnostic certainty or higher pickup rates of malignant cells.

A BAFfling liver aspirate: Metastatic high grade SMARCA4 deficient undifferentiated gastroesophageal junction carcinoma masquerading as a hematolymphoid malignancy.

Undifferentiated malignant SMARCA4-deficient neoplasms are rare, recently characterized, high grade, potentially lethal malignancies. Such tumors are characterized by the loss of BRG1 encoded by SMARCA4, a key component of the Switch/Sucrose Non-Fermenting (SWI/SNF) chromatin remodeling complex. As this complex, also referred as BAF (BRG1/BRM associated factors) complex, is involved in the epigenetic control of hundreds of genes, including those involved in lineage-specific differentiation, BAF-deficient tumors, show minimal or no differentiation and are difficult to classify. Their fine needle aspiration (FNA) cytologic features are still poorly defined. Here, we describe a 70-year-old man who presented with thickening of the wall of the distal esophagus and stomach and multiple liver and lung lesions. Liver FNA showed relatively uniform dispersed malignant cells with high nucleus: cytoplasm ratio, scant microvacuolated cytoplasm, eccentric nuclei and prominent nucleoli. Mitoses, necrotic debris, nuclear streak artifact, "ghost cells" and focal rhabdoid cytoplasmic inclusions were also present. The liver core biopsy and GI biopsies demonstrated sinusoidal and respectively submucosal involvement by a high grade undifferentiated malignant neoplasm. The tumor cells were negative for all applied markers on immunohistochemistry and flow cytometry, and only showed CD138 and weak PAX5 staining. After an initial diagnosis of hematolymphoid neoplasm, additional stains showed intact INI1 protein and loss of BRG1 protein immunoexpression, establishing the accurate diagnosis. This case highlights the difficulties and potential pitfalls encountered in the FNA diagnosis of BAF-deficient tumors, the accurate diagnosis of which is important due to their lack of response to conventional therapy and potential response to targeted therapy.

Small Cell Lung Cancer Invading the Left Atrium With Subsequent Malignant Embolic Stroke: A Case Report and Review of Literature.

Cardiac tumors are uncommon, and the vast majority of them are metastases from extracardiac sources. Metastatic spread to the heart causes symptoms by mechanical obstruction of circulation, direct myocardial invasion, or distal embolization. We herein report a case of a 58-year-old male who presented to the hospital with multilobar intracranial embolic infarcts who was found to have small cell lung cancer (SCLC) with invasion of the left atrium and pulmonary artery resulting in malignant embolic stroke. Cerebral tumor thromboembolism from SCLC is extremely rare. This case demonstrates the thromboembolic risk associated with metastatic endoluminal cardiac tumors.

Noninvasive follicular thyroid neoplasm with papillary-like nuclear features in the pediatric age group.

BACKGROUND: The most common malignant thyroid neoplasm in children is papillary thyroid carcinoma (PTC). In 2015, the Endocrine Pathology Society introduced the terminology "noninvasive follicular thyroid neoplasm with papillary-like nuclear features" (NIFTP) to replace the noninvasive follicular variant of PTC. The objective of the current study was to evaluate previously diagnosed PTC in the pediatric population, reappraise it for NIFTP, and discuss the impact of NIFTP on the risk of malignancy (ROM) for each The Bethesda System for Reporting Thyroid Cytopathology category in the pediatric population. METHODS: The electronic databases of both study institutions were searched for all thyroidectomy specimens in patients aged <19 years from June 1, 2001 through June 1, 2016. The patient's age, sex, diagnosis, previous fine-needle aspiration cytology diagnosis, and follow-up were tabulated. Slides for available cases were reviewed and cases qualifying as NIFTP were separated. RESULTS: The cohort included 101 resected nodules; cytological diagnoses were available for 95 cases. These cases included diagnoses of nondiagnostic (5 cases; 5.2%), benign (21 cases; 22.1%), atypia/follicular lesion of undetermined significance (9 cases; 9.5%), follicular neoplasm/suspicious for follicular neoplasm (FN/SFN) (25 cases; 26.3%), suspicious for malignancy (7 cases; 7.4%), and malignant (28 cases; 29.5%). On the histological follow-up, 50 cases (49.5%) were benign, 49 cases (48.5%) were malignant, and 2 cases (1.9%) were NIFTP. These NIFTP cases originally were diagnosed as FNs on fine-needle aspiration cytology. The average ROM for FNs with and without NIFTPs was 28% and 25%, respectively CONCLUSIONS: According to our rate of 1.9% for NIFTPs on reappraisal for resected nodules, this entity is likely to be less frequent in the pediatric population due to the higher prevalence of PTCs and/or more aggressive variants. NIFTPs do not appear to affect the ROM for The Bethesda System for Reporting Thyroid Cytopathology categories in the pediatric population. However, large-scale studies are necessary to determine whether NIFTPs could affect the pediatric population. Cancer Cytopathol 2018;126:27-35. © 2017 American Cancer Society.

Stratification of ovarian tumor pathology by expression of programmed cell death-1 (PD-1) and PD-ligand- 1 (PD-L1) in ovarian cancer.

BACKGROUND: Ovarian cancer is the major cause of death among gynecologic cancers with 75% of patients diagnosed with advanced disease, and only 20% of these patients having a survival duration of five years. Treatments blocking immune checkpoint molecules, programmed cell death (PD-1) or its ligand PD-ligand- I (PD-L1) have produced a beneficial and prolonged effect in a subgroup of these patients. However, there is debate in the literature concerning the prognostic value of the expression of these molecules in tumors, with immunotherapy responsiveness, and survival. We evaluated the immune landscape of the ovarian tumor microenvironment of patients, by measuring the impact of the expression of tumor PD-1, PD-L1 and infiltrating lymphocytes on stage and grade of tumors and survival, in a cohort of 55 patients with gynecologic malignancies. Most patients under study were diagnosed with advanced disease ovarian cancer. RESULTS: Our studies revealed that a low density of PD-1 and of PD-L1 expressing cells in tumor tissue were significantly associated with advanced disease (P = 0.028 and P = 0.033, respectively). Moreover, PD-L1 was expressed significantly more often in high grade tumors (41.5%) than in low grade tumors of patients (7.7%) (P = 0.040). The presence of CD3 or of FoxP3 infiltrating cells with PD-L1 in patient tumors did not impact the significance of the association of PD-L1 with high grade tumors (P = 0.040), and our analyses did not show an association between the presence of PD-1 or PD-L1 and survival. CONCLUSIONS: We conclude that a subgroup of advanced disease ovarian cancer patients with high grade tumors, expressing PD-L1, may be prime candidates for immunotherapy targeting PD-1 signaling.

Mulberry cells in the thyroid: warthin-finkeldey-like cells in hashimoto thyroiditis-associated lymphoma.

Warthin-Finkeldey type giant cells were first described in autopsies performed on young children who died during the highly lethal measles epidemic in Palermo during the winter of 1908. The cells had 8-15 nuclei without identifiable cytoplasm within the germinal centers of lymphoid organs resembling megakaryocytes. We describe a case of Hashimoto thyroiditis with an enlarging substernal throid mass. The resection specimen contained many Warthin-Finkeldey-Like Cells (WFLC) in an extranodal marginal zone lymphoma (MALT type) with focal transformation to diffuse large B-cell lymphoma. The WFLC showed nuclear features similar to those of neighboring follicular dendritic cells (FDCs), favoring the hypothesis that these cells might be the product of fusion of FDCs. This is supported by immunostaining results and the occurrence of similar cells in follicular dendritic cell sarcomas and in "dysplastic" FDCs in hyaline vascular type Castleman disease, a possible precursor of follicular dendritic cell tumors. Diagn. Cytopathol. 2017;45:212-216. © 2016 Wiley Periodicals, Inc.