Fine needle aspiration cytology of malignant schwannoma metastatic to the breast

A case of malignant schwannoma metastatic to the breast is reported. The tumor was found as a solitary breast lump in a 43-year-old woman and was clinically considered to be a primary tumor. Fine needle aspiration (FNA) smears of the mass were interpreted cytologically as a malignant neurogenic tumor, compatible with a malignant schwannoma. The patient did not have multiple neurofibromatoses. Eight months previously, an excision of a solitary nodule located in the left axilla had been performed in another hospital. Comparison of the histologic section from that excision with the FNA confirmed that the breast tumor was a metastatic malignant schwannoma, and the patient was treated accordingly.