Diagnosis of fibroadenoma in breast fine needle aspirates devoid of typical stroma.

Objective: To improve the accuracy of cytologic diagnosis in breast lesion aspirates that are cytologically suggestive of fibroadenoma (FA), exhibiting proliferating epithelial elements and bare nuclei but devoid of the typical stroma.
Study Design: A retrospective study was conducted. All available cases (89) that were aspirated and reported as suggestive of FA between 1981 and 1991 and were later biopsied were studied, and various morphologic criteria were analyzed in each smear. A control group consisted of 43 cases that were cytologically diagnosed as FA and confirmed histologically.
Results: Two criteria contributed to the cytologically suggestive diagnosis of FA. The presence of numerous "multilayered" fragments of proliferating glandular epithelium improved the positive predictive value (PPV) for FA on the suggestive smear from 67.4% to 88.3%, and the presence of numerous bare nuclei in the background improved it to 88.9%. The combined presence of both criteria improved the PPV even further, to 91.7%.
Conclusion: When an aspirate from a breast lesion is cytologically suggestive of FA despite the absence of the typical stroma, a PPV of 91.7% can be achieved, provided that the epithelial elements include many "multilayered" fragments and that the background consists of numerous bare nuclei.