Cellular composition of the angiofibromas in tuberous sclerosis.

The angiofibroma of tuberous sclerosis is associated with a proliferation of dermal spindle cells that have been considered to be fibroblasts on the basis of a variety of techniques, although some cells have a glial appearance. This study of six angiofibromas demonstrated an increase in S100-positive, peanut agglutinin-negative spindle cells in the dermis in addition to increased numbers of epidermal melanocytes. The second major spindle cell population in the dermis proved to be dermal dendrocytes based on their expression of factor XIIIa. The number of these cells decreases in older patients, in whom the lesions were generally less cellular and more fibrotic. The angiofibroma of tuberous sclerosis is a hamartoma involving increased numbers of dermal dendrocytes, neurosustentacular cells, blood vessels, and melanocytes, in addition to collagen.