SCLEROTIC FIBROMA

The clinical and histological diagnosis of sclerotic fibroma is import ant because of its potential association with Cowden's syndrome. Despi te its distinctive histological appearance the lesion is often misdiag nosed. We therefore present five of our own cases (2F, 3M) in which th e tumor was located on the head (n=2), arm (n=2) and leg (n=1), respec tively. Clinically, the lesions were white to flesh-colored firm nodul es ranging in size from 0.5 to 1.2 cm. None of our patients revealed a ny clinical evidence of Cowden's disease. Simple surgical excision see ms to be curative. Histologically, they were well-circumscribed but no t encapsulated dermal nodules composed of storiform-arranged sclerosin g collagen bundles and vimentin-positive fibroblastlike cells interspe rsed in three cases by a number of alpha-smooth-muscle actin-positive myofibroblasts. Approximately 50% of cells (dermal dendritic cells (DD )) also reacted for factor XIIIa evenly scattered throughout the lesio n in contrast to the very few (<5%) CD34+ DD found predominantly at th e lower border, thus possibly reflecting the distribution of these cel ls in normal skin. Sclerotic fibroma expands the spectrum of fibrous l esions that may express alpha-smooth-muscle actin.