Cutaneous metastasis of an osteosarcoma. A case report.

Sarcomas seldom metastasize to the skin. This report describes a rare instance of this phenomenon. A 24-year-old patient with a history of osteosarcoma (osteoblastic type) of the right humerus was seen with a cutaneous nodule on the left temple. Histologic examination of the skin showed the lesion to be a metastatic osteosarcoma. On histologic examination, a proliferation of bizarre mononucleated or multinucleated osteoblastic cells was noted in the dermis and subcutis. Although osteoid formation and calcification were not recognized, as they had been in contrast to the primary lesion, basic structures and components of the skin lesion were identical to those of the primary tumor tissue. Cutaneous metastasis from on osteosarcoma of bone is an extraordinarily rare event and, as far as we can determine, has only been reported three times.