An Elderly Male With Anemia and Thrombocytopenia

Correct!

Given the patient’s history, metastatic melanoma was considered. Morphologically, additional considerations included monoblastic leukemia, myeloma with plasmablastic features, and metastatic carcinoma. In addition to the provided immunophenotypic findings, the tumor cells were positive for pan-melanoma cocktail IHC and negative for CD64 and all other hematolymphoid markers on flow cytometry immunophenotyping, further supporting the diagnosis of melanoma. Plasma cell neoplasm was additionally excluded based on the flow findings of polytypic plasma cells without immunophenotypic abnormalities.

Melanoma is known to rarely metastasize to bone marrow, with anemia and leukoerythroblastosis reported as the most common hematologic manifestations.¹ Immunophenotypic findings are critical to exclude other processes, with the caveat that melanoma is known to express hematolymphoid markers, including CD10, CD117, CD56, and CD138.^2,3 On morphology, melanoma can have spindled or epithelioid cells. Plasmacytoid appearance and binucleation are clues to the diagnosis. The presence of melanin pigment can be helpful, but it is not always present.⁴ In many cases, melanoma is also present in the bone marrow biopsy, but occasionally it may only be present in the aspirate smears and clot sections, as in this case.

Choice A (Plasmablastic myeloma) is incorrect.

Choice B (Acute monoblastic leukemia) is incorrect.

Choice D (Metastatic carcinoma) is incorrect.

Sorry, that was not the preferred response.