Congenital hemangiopericytoma of the skin

A 5‐month‐old white boy had a pinhead red spot on his left malleolar region since birth. His mother noted progressive growth and, when he was first examined, the lesion measured 30x25x20 mm in size, had a pyramidal shape, covered by erythematous and smooth skin, with teleangiectasia. The tumor was soft on paipation and movable over the deeper structures (Fig. 1a). X‐ray examination revealed no bone abnormalities at that time. Just before the programmed incisional biopsy, the patient had a febrile episode due to upper respiratory tract viral infection during which the tumor became ulcerated, bleeding and painful (Fig. 1b). As the bleeding was constant the lesion was surgically excised, at which time the whole gelatinous mass was easily detached from the aponeurotic structures (Fig. 1c). The tumor measured 36x31 x30 mm and had a whitish, smooth cut surface crossed by small blood vessels. Histopathologic examination revealed a tumor mass extending from the mid dermis to the subcutaneous fat and composed of tightly packed fusiform cells in close opposition with lined vascular channels (Fig. 2a). There were atypical areas and mitotic figures were frequently seen. A reticulin preparation showed a dense network surrounding vessels and pericytes. The vessels branched in a staghorn configuration (Fig. 2b). The immunoperoxidase technique with monoclonal antibody anti‐Factor VIII was positive in the endothelial cells surrounded by tumor cells (Fig. 2c). Seven months after surgery the patient returned with a painful subcutaneous mass on the upper third of his left leg that was adherent to the tibial bone. X‐ray examination disclosed osteolytic lesions at the tibial base and destruction of the peroneal head (Fig. 3). The patient was submitted to radiotherapy, amputation of the left lower limb in the middle portion of the thigh and chemotherapy. He is clinically well 3 years after treatment.