A case of adenoma of the nipple: Cytopathologic features

A case of adenoma of the nipple is presented with its cytologic and histopathologic features. A42-year-old female complained of a bloody dischargefrom her right nipple.Carcinoma of the breast was suspected on the basis of the cytological findings in the nipple discharge, but no nodular lesions were found in the right breast by palpation or mammography, and total mastectomy was performed.The smear of the nipple discharge was highly cellular, with both numerous large epithelial cell clusters and dissociated single epithelial cells.These cells had a round, oval, or sometimes pleomorphic shape.The nuclei were uniform with finely granular chromatin and small conspicuous nucleoli, but enlarged nucleoli were often seen. Some cells contained hyperchromatic nuclei.Myoepithelial cells were often observed in the epithelial cell clusters and/or between the dissociated cells.Three tiny nodular lesions were found histologically, one in the middle portion of the nipple and other two beneath the nipple.These nodules were circumscribed but unencapsulated.The ducts and duct epithelial cells had markedly proliferated and formed solid nests and tubular-like structures.Myoepithelial cells and fibrous stromal cells were observed in the tumors.High cellularity and many dissociated single cells and cells with enlarged nucleolis were misleading in the cytological diagnosis of the present case.