FNA diagnosis of retroperitoneal leiomyosarcoma metastasizing to the breast

Fine-needle aspiration (FNA) biopsy is one of the first-line investigations in any breast lump, and hence cytomorphological recognition of nonmammary metastatic tumors to the breast and their distinction from primary tumors is important. Breast metastasis from extra-mammary malignancy is rare, constituting 2% of breast tumors; even rarer are metastatic leiomyosarcomas. Our patient presented with a breast lump 2 years after operative removal of a retroperitoneal leiomyosarcoma. The breast lump was confirmed to be a metastasis from the earlier primary. Herein, we report the first case of a retroperitoneal leiomyosarcoma metastatic to the breast diagnosed by Fine Needle Aspiration.