Objective: Breast cancer is the most frequently diagnosed malignancy and also the leading cause of cancer death in women worldwide. The early diagnosis of the breast carcinoma is very important in order to decide the optimal treatment. So the usefulness of core needle biopsy in breast lesions is aimed to be researched in this study.

Materials and methods: We analyzed 930 female patients retrospectively from whom core needle biopsies of the breast lesions were performed by ultrasound-guidance and histopathologically evaluated. Age, histopathologic type of the lesions, tumor grade in malignant lesions were interpreted.

Results: The histopathological diagnosis of 189 (20.32%) patients were malignant tumors, 608 (65.38%) were benign lesions such as fibrocystic changes, fibroadenomas, intraductal papillomas, mastitis, fat necrosis and adenosis where 133 (14.30%) were usual breast tissues. Among the malignant tumors 10.58% were diagnosed as special-type-of invasive invasive carcinoma like lobular, tubular, mucinous, medullary and metaplastic carcinomas, while 89.42% of the malignant tumors were classified as Invasive carcinoma of No-Special-Type (NST). Histological grading of the invasive carcinomas of no-special-type was made according to the Modified-Bloom-Richardson grading system. The ratio of grade 1,2,3 tumors were 36.09%, 52.66% and 11.25% respectively.

Conclusion: Ultrasonography-guided breast-core-needle-biopsy is the most suitable method which is used preoperatively for quick, accurate diagnosis and the histopathologically correct diagnostic rates are very high with it. Because this method is minimal invasive, it does not damage the breast aesthetically and the lesion histologically. It provides enough tissue for immunohistological studies like estrogen, progesterone receptors, HER2, MIB-1 to determine the appropriate approach to the malignant tumors and the need for neo-adjuvant theraphy or to decide for the surgical method.