Cutaneous metastases as initial manifestation of dedifferentiated chondrosarcoma of bone. An autopsy case with review of the literature.

Metastases of chondrosarcoma to the skin are uncommon. We report a case of dedifferentiated chondrosarcoma that manifested as cutaneous metastases and had an outcome of three weeks. A 69-year-old male presented with two cutaneous nodules, one in the chest and other in the inguinal area. The punch biopsy of the latter showed a poorly differentiated mesenchymal metastatic tumor. Shortly before death, an X-ray revealed a proximal epiphyseal lesion in the right humerus, radiographically interpreted as chondrosarcoma. The autopsy showed this lesion to be a dedifferentiated chondrosarcoma whose nonchondroid mesenchymal part was akin, histologically and immunohistochemically, to the cutaneous metastases. While ten previous reports of chondrosarcoma metastatic to the skin are known, we believe that this is the first case to report the cutaneous metastases of the dedifferentiated variety. Furthermore, skin metastasis preceding the diagnosis of chondrosarcoma has not been previously reported. The fact that one part of this kind of tumor can be highly undifferentiated or, else, differentiated along lines not usually reminiscent of bone tumors, can make the diagnosis of such cases extremely difficult. Most chondrosarcomas metastatic to the skin arise in bones of the extremities, including the hand. The most common type of tumor is conventional chondrosarcoma. These metastases can be either single or multiple with a slight predilection for the head and neck region. Most patients die in a mean time of 6 months after the appearance of cutaneous metastases.