Cytodiagnosis of nipple discharge: a study of 602 samples from 484 cases.

To find out the gross and microscopic differentiating features between nipple discharges (ND) due to various breast lesions, smears of 602 ND samples from 484 cases were reviewed by one of the investigators (D.K.D.). The reviewed cytodiagnoses were as follows: benign nipple discharge (59.1%), inflammatory ND (6.5%), ?papillary lesions (2.5%), papillary lesions (20.6%), papillary lesions with atypia (3.8%), duct cells with atypia (0.2%), suspicious for malignancy (0.5%), malignant ND (1.2%), and inadequate (5.6%). Following review, samples with epithelial abnormalities (?papillary lesion, papillary lesion with and without atypia, duct cells with atypia, suspicious for malignancy, and malignancy) increased from 16.6% to 30.4% of adequate samples (P < 0.0001). 37.9% unilateral ND samples showed epithelial abnormalities, as opposed to 18.9% of bilateral ND samples (P < 0.0001). Bloodstained ND showed epithelial abnormalities in 41.5% samples, as compared to 22.1% of ND with other specified gross characteristics (P < 0.0001). The samples with epithelial abnormalities differed significantly from benign and inflammatory ND in respect of frequency of benign duct cells, duct cells with atypia, papillary clusters with or without atypia, malignant cells, columnar cells, red blood cells, inflammatory cells, and background lipid vacuoles (P < 0.01 to < 0.0001). The ND samples with suspicious and malignant cytology, besides the presence of malignant cells (P < 0.0001), differed significantly from rest of the lesions in respect of foam cells (P < 0.0001), red blood cells (P < 0.01), and inflammatory cells (P < 0.05). When compared with histopathological diagnosis in 20 cases, the benign or malignant nature of the lesion was correctly identified in ND in 80% cases. The ND cytologies in 7 histologically proved malignant cases were malignancy (3 cases), suspicious for malignancy (1 case), papillary lesion with atypia (1 case), papillary lesion (1 case), and benign ND (1 case). Copyright 2001 Wiley-Liss, Inc.