FINE-NEEDLE ASPIRATION CYTOLOGY OF DUCTAL ADENOMA - REPORT OF A CASE ASSOCIATED WITH A MUCOCELE-LIKE LESION

Ductal adenoma (DA) is an uncommon breast lesion that can histological ly and clinically mimic carcinoma. We performed a fine-needle aspirati on (FNA) of a DA. Cytologically, the lesion had features overlapping w ith those of mucinous carcinoma (MC), mucocele-like lesion, lactating adenoma (LA), and in retrospect with intraductal papilloma (IP). The s mears were highly cellular and contained numerous monolayered sheets o f ductal cells with prominent punched-out, small vacuoles distending t he cytoplasm. The nuclei were mostly round to oval and had bland chrom atin. Occasionally cells with enlarged nuclei and conspicuous nucleoli were present. The background showed large mucin pools, scattered sing le cells with mild nuclear atypia, some with apocrine metaplasia, rare stripped nuclei, and a fibrovascular stromal component. Calcification s were also present. We compare our cytologic findings with those of t he lesions considered in the differential diagnosis. Due to its rare i ncidence and unusual features, DA may represent a diagnostic pitfall o n FNA. Increased awareness of ifs cytologic appearance may help preven t a misdiagnosis. (C) 1995 Wiley-Liss, Inc.