Fine-needle aspiration of well differentiated small-cell duct carcinoma of the breast

Historically, fine-needle aspiration of the female breast has been accepted as a useful modality in the diagnosis of ductal as well as other types of breast carcinoma. However, cases of well differentiated small-cell duct carcinoma can be problematic. The differential diagnoses include fibrocystic disease, papillary neoplasia, fibroadenoma, and lobular carcinoma. Retrospectively, 16 cases of well differentiated small-cell duct carcinoma have been identified in the case files of Truman Medical Center/University of Missouri-Kansas City. Patient's ages ranged from 29-81 yr, with the mean being 56.2 yr. The overall cytologic features consisted predominantly of a hypercellular specimen with cohesive and rarely discohesive cells with no demonstrable nuclear atypia. For well differentiated small-cell duct carcinoma, the mean nuclear diameter was greater than that of a red cell (6-8 microns). For the well differentiated small-cell duct carcinoma group, the mean nuclear diameter was 9.86 microns; for fibrocystic disease, 12.86 microns; for papillomas, 8.28 microns; for fibroadenomas, 9.48 microns; and for lobular carcinoma, 11.88 microns. From our data, it appears that specific attention to the clinical presentation, cytologic pattern, and nuclear diameters are useful discriminators for well differentiated small-cell duct carcinoma.