Case report 657: Malignant epithelial thymoma with osteoplastic metastases.

Malignant epithelial thymomas are slowly growing anterior mediastinal tumors. Local invasion and intrathoracic spread are not uncommon. Evidence of extrathoracic metastases are found in up to 15% of patients, most commonly in the liver, kidney, and bone. Almost all reports of thymoma metastases to bone have described purely lytic lesions. Once extrathoracic metastatic deposits are discovered, the mean extent of survival is 18 months. A case of a malignant epithelial thymoma in a young woman with diffuse sclerotic metastases to bone is reported. This case is remarkable not only for the presence and extent of the osteoblastic metastases but also for the fact that this woman lived for 6 years following the discovery of the extrathoracic bone involvement.