A 10-year-old boy develops multiple tiny, flat-topped, flesh-colored pinpoint papules on the forearms and genitalia. Biopsy shows a dense lymphohistiocytic infiltrate in an expanded dermal papilla with overlying thinned epidermis and 'claw-like' rete ridges surrounding the infiltrate. The diagnosis is:

• A Keratosis pilaris
• B Lichen planus
• C Lichen striatus
• D Lichen nitidus ✓

Explanation

Lichen nitidus histology shows a characteristic claw-like or ball-in-claw appearance where rete ridges surround a dermal papillary infiltrate. Lichen planus shows saw-tooth rete ridges and band-like infiltrate. Lichen striatus follows Blaschko lines. Keratosis pilaris shows follicular plugging without the characteristic infiltrate pattern.

Reference: Lever's Histopathology of the Skin, 11th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.