Abstract
A 47-year-old male first presented at our hospital on January 26, 1994. He had congenital portwine stain on the left side of the face, head, ear and neck. From about twenty years of age, nodular tumors began to grow on the lesions and recently grew into huge masses. He was operated six times to improve his facial appearance. Histopathologically, arteriovenous anastomotic vessels were abundant in the dermis. Moreover many capillaries and venules were also dilatated. It was suggested that the cause of hypertrophic portwine stain might be partially due to the hyperplasia of the arteriovenous anastomosis.
