Metastasis of cancer to cancer. A case of breast carcinoma metastasizing to a malignant mesothelioma.

Metastasis of cancer to cancer is exceedingly rare, the most frequent being metastasis from bronchogenic carcinoma to renal carcinoma. A case of breast carcinoma metastasizing to a fibrosarcomatous malignant mesothelioma is presented. Breast carcinoma metastasizing to another carcinoma has been reported 4 times in the past. To our knowledge no case of breast carcinoma metastasizing to a malignant mesenchymal tumor has been published. It is unknown whether metastasis of cancer to cancer is a random occurrence or is due to selective lodging, survival and growth within another malignant neoplasm.