A 48-year-old man from southern Japan presents with generalized lymphadenopathy, skin lesions, and hypercalcemia. Peripheral smear shows flower-like pleomorphic lymphoid cells. Serology is positive for human T-cell lymphotropic virus type 1. The malignant cells would be expected to show which immunophenotype?
- A CD19-positive B cells expressing CD5
- B CD8-positive T cells expressing granzyme B
- C CD4-positive T cells expressing CD25 ✓
- D CD34-positive precursor cells expressing TdT
Correct answer: C. CD4-positive T cells expressing CD25
Explanation
Adult T-cell leukaemia/lymphoma is caused by HTLV-1, endemic in southwestern Japan and the Caribbean basin, and presents with skin lesions, lymphadenopathy, and hypercalcemia. The neoplasm is a mature helper T-cell malignancy: the cells are CD4 positive, express CD25 (the IL-2 receptor alpha chain) strongly, and show the classic cloverleaf or flower nuclei on smear. B-cell markers such as CD19 belong to CLL, not this entity.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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