A 58-year-old man has slowly progressive erythematous scaly plaques and patches on the trunk over several years, initially diagnosed as psoriasis but unresponsive to topical steroids. Skin biopsy shows an infiltrate of atypical lymphocytes with convoluted cerebriform nuclei within the epidermis forming collections called Pautrier microabscesses. What is the diagnosis?
- A Psoriasis
- B Mycosis fungoides ✓
- C Nummular eczema
- D Tinea corporis
Correct answer: B. Mycosis fungoides
Explanation
Mycosis fungoides is a cutaneous T cell lymphoma presenting as chronic patches and plaques that mimic inflammatory dermatoses. Epidermotropism of atypical cerebriform T lymphocytes with Pautrier microabscesses is the diagnostic histologic feature. Psoriasis shows neutrophilic Munro microabscesses rather than atypical lymphocytes, which separates the key distractor.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.