Nodular sclerosing adenosis of breast: A diagnostic pitfall in fine needle aspiration cytology.

Fine needle aspiration cytology was performed in a 46-year-old female presenting with a breast lump and mammography suggesting a malignancy. The smears were cellular with cohesive clusters and scattered epithelial cells showing moderate nuclear pleomorphism and focal acinar formation. Stromal fragments, benign epithelial cell clusters and a few naked nuclei were noted in the background. Considering the clinical features, mammography findings as well as cytological features, a diagnosis of ductal carcinoma was suggested. Subsequent histopathological examination revealed it to be nodular sclerosing adenosis. The cytohistological correlation of this uncommon lesion, a potential pitfall in breast fine needle aspiration diagnosis which may lead to a false-positive diagnosis is discussed.