Localized hypopigmented keratoses

A 16‐year‐old girl presented with a 2‐year history of hypopigmented, hard papules involving the extensor surfaces of the forearms and lower legs. Initially, 2–3‐mm‐sized papules were present on the forearms; gradually they increased in number and spread to involve the lower legs. Her family history was unremarkable. There was a history of worsening in the summer. On examination, she was skin type 3, with multiple, round, hypopigmented, keratotic, flat‐topped papules located on the distal dorsal parts of the extremities, with a stuck‐on appearance ( Fig. 1). The papules were unrelated to follicular orifices, symmetrically distributed, and could not be detached. The lesions were not itchy. Her face, trunk, palms, and soles were spared, and no mucosal lesions were present. The nails and hair were normal. 1Numerous, hypopigmented, flat‐topped papules on the arm Histologic examination of a papule revealed orthokeratotic hyperkeratosis, mild acanthosis, mild papillomatosis, and vacuolization in basal cells. A mild lymphocytic inflammatory response was seen. There were normal amounts of melanin in the basal cell layer and no melanophages were present ( Fig. 2). 2Hyperorthokeratosis, mild acanthosis, and papillomatosis. A mild inflammatory infiltrate is present in the dermis (hematoxylin and eosin, × 100) Despite some slight differences, the clinical and histologic features appeared to be similar to cases previously described under the title “disseminated hypopigmented keratoses”. The patient was treated with 0.1% tretinoin gel and 10% salicylic acid ointment and marked improvement was observed after several weeks.