Fine-needle aspiration cytology of extramammary neoplasms metastatic to the breast.

Fine-needle aspiration (FNA) biopsy is the first-line investigation in any breast lump and hence cytomorphological recognition of nonmammary metastatic tumors to the breast and their distinction from primary tumors is important. Metastatic breast neoplasms diagnosed over a 6-yr period from 1997 to 2002 were retrieved from the database of the Department of Cytopathology and the clinical, cytopathological, histochemical, and immunohistochemical findings were correlated with the histopathology of the primary tumor. Fifteen cases of metastatic breast neoplasms were encountered constituting 1.47% of all malignant tumors of the breast diagnosed on FNA. There were 14 female patients and one male patient aged 13-80 yr. The preaspiration clinical diagnosis was either a benign breast lump or a malignancy (primary vs. metastatic). The breast lump was the initial presentation in four cases and the cytodiagnosis of a metastatic malignancy lead to the subsequent detection of the primary malignancy. These included one case each of melanoma, myeloma, rhabdomyosarcoma, and small-cell carcinoma of the lung. There were five pediatric cases that included four cases of rhabdomyosarcoma and one case of leukemic deposit. The adult cases included two cases each of melanoma, small-cell carcinoma, and myeloma; one case of choriocarcinoma; and three cases of soft-tissue sarcomas. These included two cases of malignant fibrous histiocytoma (MFH) and one case of leiomyosarcoma. The presence of unusual cytomorphological patterns on breast FNA should alert the cytopathologist to the possibility of a metastatic breast neoplasm, even if not suspected clinically. A detailed history of the patient, clinical correlation, and immunocytochemistry helps in establishing an accurate diagnosis, which avoids unnecessary surgery and ensures appropriate treatment. Copyright 2005 Wiley-Liss, Inc.