Correct answer is B: Sézary syndrome is a leukemic form of cutaneous T-cell lymphoma (CTCL) characterized by circulating malignant CD4+ T-cells. The key flow cytometry findings are: *CD4/CD8 ratio >10:1 due to a monoclonal expansion of abnormal CD4+ T-cells* Loss of CD7 and CD26, markers usually expressed on normal T-cells *Monoclonal T-cell receptor (TCR) gene rearrangement confirming malignancy* Why Other Options Are Incorrect? ❌ A. CD4/CD8 ratio <1 with loss of CD3 → More suggestive of cytotoxic T-cell disorders, not Sézary syndrome. ❌ C. Predominantly CD 14 and CD 16 positive cells → Suggests Monocytic lineage. ❌ D. CD5 and CD23 co-expression → Suggests chronic lymphocytic leukemia (CLL), not Sézary syndrome. Complete explanation: https://youtu.be/o1fMu2gbu_g?si=QbQQQDaEKx66LTz6