Atypical and suspicious categories in fine needle aspiration cytology of the breast: Histological and mammographical correlation and clinical significance

Abstract

Introduction: This study aims to correlate fine-needle aspiration specimens diagnosed as C3 (atypical, probably benign) and C4 (suspicious, probably malignant) with histology and mammography, and to evaluate these two cytology categories in terms of diagnostic usefulness and patient management. Methods: All fine-needle aspiration (FNA) specimens in categories C3 or C4 at the Maharaj Nakorn Chiang Mai Hospital, Thailand between 2000-2004 were reviewed. Results were correlated with available histological and mammographical studies. Results: 148 FNA specimens were identified, comprising 43 category C3 and 105 category C4. Histology was available in 90 cases. 14 (64 percent) C3 cases showed benign histology on biopsy and eight (36 percent) were malignant. 13(19 percent) C4 cases were benign on biopsy, whereas 55 (81 percent) were malignant. Mammographical studies were available in 56 of the histologically-proven cases. All seven cases with benign mammograms had benign histology, and all 26 cases called "highly suggestive of malignancy" were malignant on histology (five C3 and 21 C4). Of the 23 cases called "suspicious abnormality" on mammography, 14 turned out to be malignant on biopsy (one C3 and 13 C4). Conclusion: Our study supports maintaining cytology categories C3 and C4. About two-thirds of C3 cases were benign on biopsy whereas 81 percent of C4 cases were malignant (p-value is less than 0.001). There was complete correlation between histological and mammographical studies except those with equivocal mammograms. Our study supports the combined use of clinical, mammographical and cytological findings for optimal patient management. This is especially important for patients with C3 aspiration results, in order to avoid unnecessary surgery for benign lesions.