Folliculocystic and collagen hamartoma of tuberous sclerosis complex

BackgroundTuberous sclerosis complex (TSC) is an autosomal dominant disorder characterized by tumors and hamartomas in several organs including the skin.ObjectiveWe sought to describe a new type of complex hamartoma in patients with TSC.MethodsThis was a retrospective clinical and histopathologic evaluation of 6 cases.ResultsThe skin lesions consisted of large, painless, infiltrated plaques that were first noticed at birth or during early infancy on the abdomen, thigh, back, or scalp. In time, the plaques became studded with numerous follicular comedo-like openings and cysts containing and draining a keratinous or purulent material. The main histopathologic features were: abundant collagen deposition in the dermis and extending into the underlying fat; concentric, perifollicular fibrosis surrounding hair follicles; and comedones and keratin-containing cysts lined by infundibular epithelium, some of which were ruptured with secondary granulomatous reaction. Five of the 6 patients had a clinical diagnosis of TSC.LimitationsGenetic testing was performed in only one patient.ConclusionThis distinctive folliculocystic and collagen hamartoma has not been recognized previously in association with TSC.