Merkel Cell Carcinoma Presenting as a Malignant Pleural Effusion Post-COVID-19 Hospitalization: a Case Report and Literature Review

Introduction/Objective

Merkel cell carcinoma (MCC) is a rare, highly aggressive neuroendocrine carcinoma of the skin, associated with immunosuppression, UV light exposure, and the Merkel cell polyomavirus (MCPyV). Metastatic MCC diagnosed in body fluid cytology is extremely rare. Here, we report on a case of a 65-year-old male presenting with a right pleural effusion and a remote history of MCC, unknown to us during the cytologic evaluation of the effusion. To the best of our knowledge, this is the sixth case of metastatic MCC diagnosed in body fluid cytology reported in English literature, and the first one reported in a patient previously admitted for COVID-19 pneumonia.

Methods/Case Report

A 65-year-old male presented with dyspnea and acute hypoxic respiratory failure. Past medical history was significant for squamous cell carcinoma of the right forearm excised four months prior and ulcerative colitis. The patient had two recent hospitalizations for COVID-19 pneumonia. Chest x-ray on admission demonstrated an enlarged, loculated right pleural effusion. Emergent thoracentesis was performed and 1500 cc of bloody pleural fluid was sent for cytology. The patient’s respiratory status improved. A ThinPrep and a cell block were prepared. Both displayed clusters of small round blue cells with hyperchromatic nuclei, scant cytoplasm, and fine chromatin in a background of rare mesothelial cells, macrophages, and numerous lymphocytes. Immunohistochemical (IHC) studies showed CK20, AE1/AE3, and CAM 5.2 in a perinuclear dot-like staining pattern. CD56, chromogranin, and synaptophysin were also positive. Ki-67 proliferative index was about 40%. TTF-1 was negative, while CD45 highlighted background lymphocytes. The primary care physician was contacted and the patient’s past medical history was significant for MCC. Subsequent MCPyV and SATB2 demonstrated nuclear positivity in the tumor cells. Diagnosis of MCC was done.

Results (if a Case Study enter NA)

NA

Conclusion

MCC is a highly aggressive malignancy rarely reported in body fluids. MCC should be included in the differential diagnosis of malignant pleural effusions, especially in cases of the small blue round cells. Using IHC, like CK20 and neuroendocrine markers including the newer SATB2, can lead to an accurate diagnosis. Additional reporting of such cases may increase awareness, especially where prior history is not readily available, such as in this present instance.

Peripheral T-cell Lymphoma, NOS With Epstein-Barr Virus Positivity in an Elderly Patient With Myelodysplastic Syndrome: An Autopsy Case Report

Casestudy

Epstein-Barr virus (EBV)-associated peripheral T-cell lymphomas are a group of aggressive neoplasms with a geographic predilection for South America and Asia, but are very rare in Western populations.

Results

We report a case of a 74-year-old Caucasian female who presented with pancytopenia and B symptoms with EBV-IgG detected on admission. Past medical history included: ITP, chronic urticaria, and recently diagnosed myelodysplastic syndrome (MDS) on bone marrow biopsy one month prior to admission. Excisional biopsies of an enlarged right neck lymph node (repeated within 6 months) and right axillary lymph node five years ago were negative for a lymphoproliferative disorder at the time. Repeated bone marrow biopsy, performed during the current admission, confirmed the diagnosis of MDS, with scattered T-cells without aberrant immunophenotype. Despite aggressive treatment from multiple specialties, the patient deteriorated and expired four weeks later from complications of MDS. At autopsy, there was diffuse lymphadenopathy involving the mediastinum, axilla, pelvis and peripancreatic fat. Lymph node sections demonstrated nodal architecture effacement by diffuse, vaguely nodular lymphoid infiltrates.

Histologically, the infiltrates were composed of medium to large lymphocytes with round to slight irregular nuclei, rare Reed-Sternberg-like multinucleated cells, clumped chromatin, and indistinct nucleoli. Individual cell necrosis was abundant with mitotic figures readily identifiable. Immunohistochemistry revealed CD2+ CD3+ neoplastic T-cells that co-express MUM1 and a subset of CD30, while negative for CD4, CD5, CD8, CD56, ALK1, and TDT. EBV-encoded RNA in-situ hybridization was focally positive. The final postmortem diagnosis was peripheral T-cell lymphoma, not otherwise specified (NOS), with focal EBV positivity.

Conclusion

Co-existence of a de-novo MDS and non-Hodgkin lymphoma without any prior chemotherapeutic exposure is a highly unusual finding, although MDS-like presentations can occur with EBV-associated lymphomas. Peripheral T-cell lymphoma, NOS is an aggressive lymphoma and EBV positivity has been found correlated with a poor prognosis. This case demonstrates how postmortem examination remains an important tool in clinical- pathological correlation and highlights the potential pathogenetic role EBV plays in MDS and T-cell lymphoma.