A 68-year-old man presents with the clinical presentation shown in the diagram, marked as **A** — diffuse erythroderma with fine scaling involving >80% of body surface area. He reports severe pruritus, ectropion, and generalized lymphadenopathy. Flow cytometry of peripheral blood reveals CD4+ T cells with cerebriform nuclei at a count of 1200/μL, with a CD4:CD8 ratio of 12:1. Skin biopsy shows epidermotropic atypical lymphocytes with a T-cell receptor clone identical to that found in the blood. According to the WHO-EORTC classification, what is the stage and disease category of this patient's condition?
A. Stage IIIA — Plaque-stage mycosis fungoides with lymphadenopathy
B. Stage IB — Generalized patch mycosis fungoides without blood involvement
C. Stage IIA — Patch-stage mycosis fungoides with folliculotropism
D. Stage IVA1 — Sézary Syndrome (leukemic, erythrodermic CTCL)
Explanation
Why "Stage IVA1 — Sézary Syndrome (leukemic, erythrodermic CTCL)" is right
The patient meets all three diagnostic criteria for Sézary Syndrome as defined by WHO-EORTC 2022: (1) erythroderma involving ≥80% BSA (shown as A in the diagram), (2) generalized lymphadenopathy, and (3) clonal CD4+ neoplastic T cells with cerebriform nuclei in peripheral blood at ≥1000/μL with CD4:CD8 ratio ≥10 and TCR clone identity between blood and skin. These findings define advanced-stage CTCL classified as Stage IVA1, representing the leukemic, most aggressive erythrodermic variant of cutaneous T-cell lymphoma.
Why each distractor is wrong
Stage IIIA — Plaque-stage mycosis fungoides with lymphadenopathy: Plaque-stage MF (marked as B in the diagram) is a different morphology and disease category. Stage IIIA represents patch/plaque disease with lymphadenopathy but WITHOUT the leukemic blood involvement (Sézary cells ≥1000/μL and abnormal CD4:CD8 ratio) that defines Sézary Syndrome.
Stage IIA — Patch-stage mycosis fungoides with folliculotropism: This represents early-stage, non-erythrodermic MF. The patient's diffuse erythroderma (≥80% BSA), blood involvement, and Sézary cell criteria place him far beyond Stage II disease.
Stage IB — Generalized patch mycosis fungoides without blood involvement: This stage explicitly excludes blood involvement. The patient has documented Sézary cells ≥1000/μL with abnormal CD4:CD8 ratio and TCR clonality, which automatically excludes Stage IB and mandates Stage IVA1 classification.
High-YieldNEET PG
Sézary Syndrome = erythroderma (≥80% BSA) + lymphadenopathy + Sézary cells ≥1000/μL (or CD4:CD8 ≥10 or TCR clone match) = Stage IVA1 CTCL with median OS 2–4 years; mogamulizumab (anti-CCR4) is the preferred targeted agent per MAVORIC trial.
