Simplified nuclear grading of fine-needle aspirates of breast carcinoma: concordance with corresponding histologic nuclear grading and flow cytometric data.

Although histologic grading of breast carcinoma is widely practiced by most pathologists, cytologic grading of fine-needle aspirates (FNA) of this neoplasm is not commonly done. This study addresses the issue of the accuracy of a new classification system, a simplified Nuclear Grading (NG) system based on the criteria proposed by Black et al. (Surg Gynecol Obstet 1955;100:543) in FNA of breast carcinoma. We reviewed 100 cases of breast carcinoma, initially diagnosed by fine-needle aspiration biopsy (FNAB) with subsequent histologic confirmation, consisting of 94 ductal, five lobular, and one medullary carcinoma. NG of Papanicolaou's stained materials were reviewed twice independently by two pathologists and then were compared to the original histologic NG. The concordance rate with histology ranged from 80-90%. Intraobserver reproducibility was 86 and 88%, while interobserver reproducibility ranged from 84-88%. Of the 88 cases with corresponding flow cytometic (FCM) data, there were 35 diploid and 53 aneuploid cases. Fifty-nine (95%) of histologic high NG were aneuploid or diploid with high S-phase fraction (SPF), while 20 (77%) of histologic low NG were diploid with low SPF. This study confirms that nuclear grading of FNA of breast carcinoma using a simplified NG system has a high concordance with histology, has high intraobserver and interobserver reproducibility, and that this grading system correlates well with FCM analysis when tumors are simply divided based on NG as high or low grade.