A 60-year-old uncircumcised man has a well-demarcated, moist, velvety, erythematous plaque on the glans penis present for one year. Biopsy shows full-thickness epidermal dysplasia with atypical keratinocytes and intact basement membrane. Diagnosis:

• A Zoon balanitis
• B Lichen planus
• C Invasive squamous cell carcinoma of the penis
• D Erythroplasia of Queyrat ✓

Explanation

Erythroplasia of Queyrat is squamous cell carcinoma in situ (Bowen disease) arising on the glans or mucosal prepuce as a shiny red velvety plaque. Histology shows full-thickness keratinocytic atypia with an unbreached basement membrane, distinguishing it from invasive penile carcinoma. Zoon plasma cell balanitis shows a band-like plasma cell infiltrate without dysplasia, which excludes option A.

Reference: Rook's Textbook of Dermatology, 9th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.