Persistent linear plaques

Case history

For eight months, a 45-year-old meat worker has had a persistent, mildly itchy rash on his abdomen, hips and proximal thighs. He reports no identifiable triggers, and he has no prior history of skin problems and no personal or family history of atopy or psoriasis. He is otherwise well, and is on no medications. On examination, red, slightly scaly thin plaques in a linear (‘digitate’) orientation are observed (Figure). Lymph nodes, liver and spleen are not palpable. Biopsy from two sites shows dermatitis with mild spongiosis and psoriasiform hyperplasia of the epidermis, exocytosis of lymphocytes and a perivascular and interstitial lymphocytic infiltrate of the upper dermis with no cellular atypia.