Small cell variant anaplastic large cell lymphoma presenting as leukemia: A case report and review of Literature

Anaplastic large cell lymphoma (ALCL) is a subcategory of the mature T-cell neoplasm characterized by sheets of cluster of differentiation (CD)30-positive pleomorphic large cells mostly present as lymphadenopathy. Here, we describe a case of Small cell variant ALCL with leukemic presentation without lymphadenopathy. A 68-year-old male presented with fatigue and weakness; examination revealed a total leukocyte count of 295,000/uL. The peripheral smear showed cells having cerebriform nuclei comprising 90% of the leukocytes. The flow cytometry showed that the cells were immunopositive for CD3 (weak), CD4, CD7, and negative for the rest of the markers. The cell blocks from the peripheral blood showed cells with immunopositivity for CD30, anaplastic lymphoma kinase (ALK), and Epithelial membrane antigen (EMA). A diagnosis of the small cell variant of ALK-positive ALCL was made. Due to the presence of atypical pleomorphic cells without lymphadenopathy, the case has a diagnostic dilemma with differential diagnosis of Sezary syndrome, T-cell prolymphocytic leukemia, and adult T-cell leukemia/lymphoma. Karyotyping and additional immunohistochemistry help for the confirmation of the diagnosis.