Atrophic dermatofibroma. Elastophagocytosis by the tumor cells

A 55-year-old woman presented with an asymptomatic red plaque on the left u pper back for 6 or 7 years. The lesion was depressed in response to finger pressure. The clinical diagnosis was anetoderma. Histopathologically, the c haracteristic cells of cellular dermatofibroma proliferated within the thin ned dermis, which showed atrophy of about 60 or 70%. The proliferated cells were positive for factor XIIIa and negative for CD34. The involved dermis showed the loss of elastic fibers on elastica van Gieson stain. Electron mi croscopically, the proliferating cells phagocytized the elastic fibers. We report a typical case of atrophic dermatofibroma and show the possibility t hat the cause of this disease might be elastophagocytosis between the colla gen fibers by the dermatofibroma cells.