A 62-year-old man presents with generalised exfoliative erythroderma affecting >90% BSA, pruritus, and marked scaling over 8 weeks. Lymph node biopsy shows large atypical lymphocytes with cerebriform nuclei. Blood smear reveals Sézary cells >1000/mm³. Which underlying diagnosis best explains this erythroderma?

• A Sézary syndrome ✓
• B Psoriatic erythroderma
• C Erythrodermic CTCL — mycosis fungoides transformation
• D Drug-induced erythroderma

Explanation

Sézary syndrome is the leukemic variant of cutaneous T-cell lymphoma, defined by the triad of erythroderma, peripheral blood Sézary cells >1000/mm³ (or >10% of lymphocytes), and lymphadenopathy. The cerebriform nuclear morphology is pathognomonic. While mycosis fungoides can rarely progress to erythroderma, the peripheral blood involvement with Sézary cells defines Sézary syndrome as a distinct entity. Drug-induced and psoriatic erythroderma lack these haematological hallmarks.

Reference: Neena Khanna Illustrated Synopsis of Dermatology & STD, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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