Follicular Eruption on Arms and Legs—Quiz Case

Abstract

A 17-year-old boy with congenital absence of the intrahepatic bile ducts owing to Alagille syndrome presented with a pruritic eruption of 3 months’ duration. He also reported a new problem, seeing “dark spots” at night. His medical therapy included bile acid–binding resins and supplementation of fat-soluble vitamins. His chronic jaundice was unchanged. Physical examination revealed jaundice and numerous 2to 8-mm follicular, keratotic erythematous papules on the distal extensor surfaces of his arms and legs (Figure 1). His vitamin A level was 11 μg/dL (reference level, 26-72 μg/dL), and his carotene level was less than 2 μg/dL (reference level, 9-190 μg/dL). (To convert vitamin A and -carotene to micromoles per liter, multiply by 0.0349 and 0.01863, respectively.) Treatment resolved his lesions and vision changes. A punch biopsy specimen was obtained from the forearm for histopathologic evaluation (Figure 2 and Figure 3). What is your diagnosis?