Cutaneous metastasis of extraskeletal osteosarcoma arising in the mediastinum.

Cutaneous metastases have been reported in 5%-10% of patients with internal malignancy. The most common clinical features are the sudden appearance of discrete, firm, and nontender nodules in a particular area of the body. The most frequent metastatic site of extraskeletal osteosarcoma (ESOS) is the lungs. Cutaneous metastasis of ESOS is rare. To our knowledge, only one case of ESOS has been reported with skin metastasis, histopathologically classified as the osteoblastic subtype. Here, we describe a case of chondroblastic ESOS arising in the mediastinum with metastasis to the skin. Our patient presented with a scalp nodule after diagnosis of primary ESOS at the mediastinum.