Journal of Hematopathology最新文献

An 18-year-old female presented with a 4.5 cm abdominal mass. Biopsy showed sheet-like growth of large tumor cells with round to oval nuclei, 1-2 nucleoli, and abundant cytoplasm. Immunohistochemistry showed strong, uniform CD30 staining and cytoplasmic ALK staining. B-cell markers (CD20, CD79a, PAX5, kappa/lambda) and T-cell markers (CD2, CD3, CD4, CD5, CD43, granzyme B, T-cell receptor-β) were negative. Other hematopoietic markers (CD45, CD34, CD117, CD56, CD163, EBV) were negative, but CD138 was positive. Non-hematopoietic markers showed desmin positivity and negativity for S100, melan A, HBM45, PAX8, PAX2, WT1, MYO-D1, myogenin, pancytokeratin, and CAM5.2. Sequencing identified PRRC2B::ALK fusion. A diagnosis of epithelioid inflammatory myofibroblastic sarcoma (EIMS) was made. EIMS is a rare, aggressive form of inflammatory myofibroblastic tumor typically presenting in children and young adults. The tumor comprises large epithelioid cells that express ALK and often CD30. ALK-positive ALCL has a similar age range and also is a large-cell tumor expressing CD30 and ALK. Other ALK-positive neoplasms (e.g., carcinomas, ALK-positive large B-cell lymphoma, ALK-positive histiocytosis) typically lack CD30 and have distinct clinicopathologic features that aid diagnosis. Hematopathologists need to distinguish EIMS from ALK-positive ALCL, which frequently shows loss of pan-T-cell antigens. Careful morphologic evaluation for the hallmark cells of ALCL and comprehensive phenotyping are critical to avoid this diagnostic pitfall. If known, the ALK rearrangement partner gene may also provide diagnostic clues; for example PRRC2B::ALK and RANBP2::ALK occur in EIMS but not ALCL.

We report the case of a 66-year-old man with a known history of IgD multiple myeloma (MM) which was admitted to hospital because of acute renal failure. Routine PCR testing on admission yielded a positive result for SARS-CoV-2 infection. Examination of the peripheral blood (PB) smear revealed 17% lymphoplasmacytoid cells and a few small plasma cells mimicking morphological changes frequently seen in viral diseases. However, flow cytometric examination showed 20% clonal lambda-restricted plasma cells being consistent with a diagnosis of secondary plasma cell leukemia. Circulating plasma cells as well as similar appearing lymphocyte subtypes such as plasmacytoid lymphocytes are frequently observed in infectious disorders such as COVID-19, so that the lymphocyte morphology in our patient's case could have been easily misinterpreted as typical COVID-19-induced changes. Our observation highlights the importance of incorporating clinical, morphological, and flow-cytometric data in distinguishing between reactive and neoplastic lymphocyte changes because misinterpretation may affect disease classification and, beyond that, clinical decision-making, which may have serious consequences for patients.

We report the case of a 66-year-old man with a known history of IgD multiple myeloma (MM) which was admitted to hospital because of acute renal failure. Routine PCR testing on admission yielded a positive result for SARS-CoV-2 infection. Examination of the peripheral blood (PB) smear revealed 17% lymphoplasmacytoid cells and a few small plasma cells mimicking morphological changes frequently seen in viral diseases. However, flow cytometric examination showed 20% clonal lambda-restricted plasma cells being consistent with a diagnosis of secondary plasma cell leukemia. Circulating plasma cells as well as similar appearing lymphocyte subtypes such as plasmacytoid lymphocytes are frequently observed in infectious disorders such as COVID-19, so that the lymphocyte morphology in our patient's case could have been easily misinterpreted as typical COVID-19-induced changes. Our observation highlights the importance of incorporating clinical, morphological, and flow-cytometric data in distinguishing between reactive and neoplastic lymphocyte changes because misinterpretation may affect disease classification and, beyond that, clinical decision-making, which may have serious consequences for patients.