Abstract
Alveolar rhabdomyosarcoma (RMS) is primarily a malignancy of childhood and adolescence. While RMS is rare in adults, the breast and the bone marrow are known but uncommon sites for metastatic disease. Bone marrow is also a known sanctuary site for metastatic breast cancer. We present the case of a woman with a remote history of breast cancer and RMS who developed anemia and thrombocytopenia of unknown etiology. Additional laboratory tests were negative for a cause; therefore, the decision was made to proceed with a bone marrow biopsy. The initial biopsy results were consistent with breast cancer metastasis. Subsequent diagnostic imaging of the breast led to biopsy of an enlarging morphologically benign breast mass, unexpectedly yielding alveolar RMS. This unanticipated diagnosis led to revaluation of the bone marrow, this time showing synchronous metastases from breast carcinoma and alveolar RMS. Imaging findings of this patient, along with literature review of RMS imaging characteristics, will be reviewed.