A 22-year-old man has widespread flat, hypopigmented, pityriasis versicolor-like macules and patches since childhood, along with multiple flat warts. Biopsy shows pleomorphic keratinocytes with blue-grey cytoplasm and clumped keratohyaline granules. He now has a squamous cell carcinoma on sun-exposed skin. What is the underlying defect?

• A Inherited impairment of cell-mediated immunity permitting widespread HPV 5 and 8 infection ✓
• B Germline mutation of the EVER1/TMC6 gene causing susceptibility to poxvirus infection
• C Acquired CD4 depletion from untreated HIV allowing disseminated HSV
• D Defective desmosome proteins causing widespread epidermal dysadhesion

Explanation

Epidermodysplasia verruciformis is usually autosomal recessive, with mutations in EVER1 (TMC6) or EVER2 (TMC8) impairing cell-mediated immunity against specific HPV types, chiefly 5 and 8. Infected cells show the described blue-grey cytoplasm, and about a third of patients develop cutaneous SCC in sun-exposed areas, so strict photoprotection is mandatory. The genes predispose to HPV, not poxvirus, ruling out option B.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.