Nuclear grooves in fine‐needle aspiration biopsies of breast lesions: Do they have any significance?

Abstract

Nuclear grooving is a recognized morphologic feature frequently seen in papillary carcinoma of the thyroid. This feature is also occasionally seen in other nonneoplastic and neoplastic conditions. Nuclear grooves have been described in tubular carcinoma of the breast. However, the significance of nuclear grooves in benign and malignant conditions of the breast has been rarely studied. In a retrospective study, we searched for the presence of nuclear grooves in Papanicolaou-stained and Diff-Quik-stained fine-needle aspiration biopsies (FNAB) of 50 cases of primary breast carcinoma, 25 cases of proliferative breast disease, and 25 cases of fibroadenoma. In addition, 10 cases of metastatic breast carcinoma diagnosed by FNAB were reviewed. Nuclear grooves were identified in 39 of 50 (78%) of the histologically confirmed primary breast carcinomas and in 9 of 10 (90%) of the cases of metastatic breast carcinoma in the Papanicolaou-stained smears. Nineteen of 50 (38%) of the cases of proliferative breast disease/fibroadenoma showed nuclear grooves in the Papanicolaou-stained smears. The difference between the percentage of cases showing nuclear grooves seen in the Papanicolaou-stained primary breast carcinomas and metastatic breast carcinomas compared with the benign breast lesions was statistically significant (P < 0.001 in the primary breast carcinoma cases and P < 0.01 in the metastatic breast cancer cases). Nuclear grooves were identified less often in the Diff-Quik-stained smears, and their presence in malignant lesions versus cases diagnosed as benign breast disease was not statistically significant. This study suggests that, although the presence of nuclear grooves is more frequently seen in malignant breast lesions, their presence cannot totally exclude the possibility of benign breast disease. The presence of nuclear grooves, however, may serve as a diagnostic clue in metastatic tumors of unknown primary. Diagn. Cytopathol. 1998;18:333–337. © 1998 Wiley-Liss, Inc.