This is the first known case report of primary cutaneous chondrosarcoma that later metastasized to the brain. One case of cutaneous chondroblastic osteosarcoma was reported in the literature. However, chondrosarcoma arising from the skin has not been previously reported. Metastasis of chondrosarcoma to the brain is also rare. Since 1975, fewer than 5 cases of metastatic chondrosarcoma to the brain have been reported. The patient is an 84-year-old man with a medical history of cutaneous chondrosarcoma on his left forehead resected in 2009. He came to the Winthrop University Hospital in 2011 with left-sided weakness, facial droop, and slurred speech. A CT of the head showed multiple hemorrhagic lesions in the supratentorial compartment. A total body bone scan was performed and showed no scintigraphic evidence of bone lesions. The patient subsequently underwent right frontal craniotomy. The pathologic diagnosis was metastatic chondrosarcoma. Before reaching a diagnosis of primary cutaneous chondrosarcoma, pathologists should exclude chondroid syrigoma, a cutaneous neoplasm that can show metaplasia into cartilage and bone. Clinically, it is also important to exclude a possible lesion of the same category in the bone or extraskeletal sites. The pathogenesis of a cartilaginous lesion in the skin is not well studied owing to its rarity. Based on embryogenesis, skin is derived from ectoderm, whereas bone and cartilage are derived from mesoderm. The contemporary belief is that cell types in each germ layer cannot cross from one to another. However, this concept has been challenged recently by research that studied transdifferentiation of different tissue lineages. A study published in 2006 in Thailand accomplished in vitro osteogenesis from human skin-derived precursor cells. It explained the potential of skin appendages to form mesenchymal tumors, such as chondrosarcoma. This case report may prompt future research into whether cartilaginous tumor can have a primary cutaneous origin.
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