Performance of breast fine needle aspiration as an initial diagnostic tool: A large academic hospital experience

Abstract

Background: The clinical performance of the Yokohama reporting system for breast cytology remains uncertain.

Methods: In this study, we retrospectively evaluated 318 breast fine needle aspirations (FNABs) from Los Angeles County Hospital over a five-year period, analysing data for breast cytology, histology, and radiology.

Results: Among 318 breast FNAB cases, 78.3% (249/318) were benign and 5.3% (17/318) malignant. Of 83 cases with follow-up histology, 14.5% (12/83) were insufficient, 66.3% (55/83) were benign, and 16.9% (17/83) were malignant. Of 55 benign cases, 61.8% (34/55) were fibroadenoma and 9 (9/55, 16.4%) were fibrocystic changes. Two cases were diagnosed as "atypical" but confirmed "benign" on core needle biopsy (CNB). No "suspicious" cases were found. Seventeen malignant cases were confirmed by CNB, including 70.6% (12/17) invasive ductal carcinoma, 11.8% (2/17) invasive lobular carcinoma, and one malignant phyllodes tumour. Receptor studies on cell blocks of three malignant cases showed concordant results with CNB results. In addition, 82.2% (148/180) of lesions with Breast Imaging-Reporting and Data System (BI-RADS) scores of 2 or 3 were benign and 92.3% (12/13) BI-RADS score 5 lesions were malignant on FNAB. Finally, 90% (67/74) of BI-RADS 4a lesions were benign, and 97% (36/37) of fibroadenomas were BI-RADS score 4a.

Conclusion: This, by far the largest U.S. breast cytology study, showed 93.3% sensitivity, 100% specificity, 100% positive predictive value, and 98.2% negative predictive value for breast FNAB. Women with breast lesions of BI-RADS score 3 or less have a low risk of malignancy; FNAB would contribute to the reduction of excisional biopsies. FNAB can be considered as an initial diagnostic tool for BI-RADS 4 mass/lesions and satellite lesions, as well as for triaging patients.

Keywords: Breast cytology; and radiology correlation; cytology; fine needle aspiration; histology.

FIGURE 1

Examples of cases reported in the benign, atypical, and malignant categories. (A,B) A case with bland ductal epithelial cells, myoepithelial nuclei, and stromal fragments. This case was reported as benign‐fibroadenoma on cytology and confirmed by histology (A: Diff‐Quick, ×200; B: Pap, 200×). (C) An atypical stromal fragment with mild hypercellularity, mild nuclear enlargement, and atypia, raising the possibility of a low‐grade phyllodes tumour. This case was reported as atypia on cytology, and histology showed a cellular fibroadenoma (Diff‐Quick, 200×). (D‐F) Clusters of glandular cells with enlarged, pleomorphic, hyperchromatic nuclei, and high N/C ratio. This case was reported as malignant on cytology, and histology showed invasive ductal carcinoma D: (Diff‐Quick, 200×; E: Pap, 200×; F: H&E on cell block, 200×). (G‐I) Discohesive spindle cells with enlarged, pleomorphic, hyperchromatic nuclei, conspicuous nucleoli, and high N/C ratio. This case was reported as malignant on cytology, and histology showed malignant phyllodes tumour (G: Diff‐Quick, 200×; H: Pap, 200×; I: H&E on cell block, 200×)

FIGURE 2

Immunohistochemistry of oestrogen receptor (ER) and progesterone receptor (PR) performed on the cell block. (A) ER was strongly positive in about 90% of tumour cells (200×). (B) PR was strongly positive in about 90% of tumour cells (200×)