Unusual cases of metastases to the breast. A report of 17 cases diagnosed by fine needle aspiration.

BACKGROUND: Although nonmammary tumors metastatic to the breast are relatively uncommon, a correct diagnosis is essential to appropriate management. Radiologically these lesions are single, round, discrete lesions without the spiculations of primary malignancies. Fine needle aspiration biopsy (FNAB) may provide a definitive diagnosis, thereby sparing patients unnecessary surgery. CASES: Seventeen cases of non mammary malignancies diagnosed by fine needle aspiration of the breast were identified in the cytopathology files at three different institutions from 1989 to 1999. Three of the cases are of particular interest, including a mucoepidermoid carcinoma of salivary gland origin and a small cell undifferentiated carcinoma of rectal origin, neither of which has been reported in the literature previously. The third case was a male with a breast mass that was originally thought to be primary based on clinical, cytologic and immunocytochemical features but subsequently was determined to be a metastasis from the lung. CONCLUSION: Virtually any malignancy may metastasize to the breast. FNAB is the best approach to the diagnosis of tumors that either clinically or radiographically are not typical of primary breast tumors. Extramammary neoplasms metastatic to the breast may be definitively diagnosed by FNAB, resulting in the most appropriate as well as cost-effective patient management.