Striking linear presentation of type I pityriasis rubra pilaris in a young man

A 31-year-old man presented with a 3-month history of moderately pruritic salmon-coloured plaques forming a continuous linear column from the upper chest to the lower abdomen anteriorly and from the nape of the neck to the sacral region posteriorly. Additional findings included erythematous plaques with coarse lamellated scale on the forehead and eyebrows, and waxy palmoplantar keratoderma. Histopathological examination showed psoriasiform epidermal hyperplasia with alternating orthokeratosis and parakeratosis, and a superficial perivascular lymphocytic infiltrate.