Analysis of false positive and false negative cytological diagnosis of breast lesions

Objectives: To study the reasons for interpretive errors in false negative and false positive diagnosis of breast carcinoma on fine needle aspiration cytology material. Methods: We reviewed only those cases cytohistological discrepancies were f ound, cytologic material was abnormal and to misinterpreted or both, Results: There was only one false negative case (false negative fraction 0. 32%) proved histologically as ductal carcinoma and four false positive case s (false positive fraction 1.2%); 2 fibroadenoma; 1 fibrocystic disease; an d 1 stromal fibrosis. Smears of the two false positive fibroadenoma cases s howed very high cellularity, overcrowded clusters and frequent stripped nuc lei, The fibrocystic case showed tight clusters of apocrine cells and sheet s of loosely aggregated macrophages that were over interpreted, Smears of t he false negative ductal carcinoma was hypocellular overall, and the cells showed minimal nuclear pleomorphism Conclusion: Overcrowded clusters and hypercellular smears should be careful ly assessed for uniformity of cells and detailed nuclear and cytomorphologi cal features. If the full-blown malignant cytomorphological changes are not visible, a diagnosis of suspicious or inconclusive should be made and froz en section recommended before surgery. Hypocellularity and relatively nucle ar monomorphism are the reasons for failure to diagnose malignant breast le sions. Careful attention should be paid to extreme nuclear monomorphism and absence of naked bipolar cells, A cytologically atypical or suspicious dia gnosis together with positive radiological and clinical findings should sug gest a diagnosis of malignancy.