Synchronous breast carcinoma and peritoneal mesothelioma.

Breast cancer may be associated with other primary cancers via germline mutations; however, sporadic occurrences of other malignancies are rare. With increased use of advanced breast cancer imaging, including MRI and PET/CT, other incidental synchronous cancers are increasingly identified. Such cases can represent unique diagnostic and treatment challenges. Here, we present a case of a young woman diagnosed with primary breast cancer who underwent imaging studies identifying an incidental primary peritoneal mesothelioma.