Mycosis Fungoides — SCE Dermatology MCQ

Correct answer: E — Large cell transformation indicates aggressive behaviour with significantly worse prognosis — median survival approximately 1-2 years after transformation

The correct answer is E: Large cell transformation indicates aggressive behaviour with significantly worse prognosis, median survival approximately 1-2 years after transformation. Large cell transformation (LCT), defined histologically as large cells (more than four times the size of a small lymphocyte) comprising over 25% of the dermal infiltrate or forming nodular aggregates, represents a biological shift towards a more aggressive clonal population. The British Association of Dermatologists and UK Cutaneous Lymphoma Group guidelines identify large cell transformation in skin as one of four independent adverse prognostic factors in advanced mycosis fungoides/Sezary syndrome, alongside age over 60, raised LDH, and stage IV disease, with these factors stratifying patients into markedly different five-year survival risk groups. In a patient already at tumour stage (T3) with scalp nodules, biopsy-confirmed LCT confirms this adverse transformation and mandates escalation of management (systemic therapy, CD30 testing for brentuximab vedotin eligibility, MDT referral to a supranetwork skin lymphoma service) rather than continued skin-directed therapy alone.

Reference: https://www.nice.org.uk/guidance/conditions-and-diseases/skin-conditions