Basal cell carcinoma developing in a nevus flammeus.

A 44-year-old man with Sturge-Weber syndrome developed a basal cell carcinoma at the site of a nevus flammeus on his right cheek, which had been treated with a course of grenz rays at six years of age without obvious improvement. He also exhibited erythematous papulovesicular lesions on the upper trunk, which histologically proved to be transient acantholytic dermatosis. The association of nevus flammeus and basal cell carcinoma is extremely rare; to the best of our knowledge, only four similar cases have been previously reported.