Adenoma of the nipple. Cytopathologic features.

The cytologic appearances of two examples of adenoma of the nipple are described. The cellular samples from both lesions contained large numbers of epithelial cells, which were present both singly and in numerous clusters. The uniform nuclei contained finely distributed chromatin and inconspicuous nucleoli. Some of the cells varied in size and shape; a few had hyperchromatic nuclei. Small amounts of cellular debris, inflammatory cells and hemosiderophages were also present. Adenoma of the nipple can usually be distinguished cytologically from other lesions that may involve the nipple, such as Paget's disease, adenocarcinoma, fibrocystic disease, mammary duct ectasia, intraductal papilloma and chronic subareolar abscess; the cellular features of fibroadenoma, however, overlap those of adenoma and may cause diagnostic confusion. The increasing use of cellular samples obtained from breast lesions underscores the importance of recognizing this uncommon neoplasm and its cytologic manifestations. Adenoma of the nipple can be treated successfully by limited resection, and preoperative recognition will obviate unnecessary extensive surgery.