Radial scar and carcinoma of the breast: microscopic findings in 32 cases.

We retrospectively reviewed the microscopic findings in 32 histologically confirmed radial scars in 31 women diagnosed in our unit during 1994-1998. The median age at diagnosis was 53 years (range 47-63 years). Thirty-one (97%) of 32 lesions presented as screen detected mammographic abnormalities (28 stellate lesions, 2 microcalcifications and only 1 architectural distortion). One lesion presented as a palpable breast mass. Stereotactic or ultrasound-guided fine needle aspiration cytology (FNAC) was performed in 28 cases. Cytological analysis of FNAs revealed malignant cells (C5) in 8 (29%) cases, highly suspicious cells (C4) in 3 (11%) cases, atypical benign cells (C3) in 7 (25%) cases and benign epithelial cells (C2) in 10 (35%) cases. All non-palpable lesions were surgically excised following wire localization. Histological examination of the breast specimens (mean weight=16 g) demonstrated, in addition to a radial scar, 6 invasive carcinomas (2 infiltrating ductal, 2 tubular, 1 mixed ductal/lobular and 1 secretory carcinoma) and 4 ductal carcinoma in situ lesions (2 high grade, 1 high grade with micro-invasion and 1 low grade) arising in the radial scar. Of the remaining cases the radial scar was associated with atypical epithelial hyperplasia in 2 cases and regular epithelial hyperplasia in 17 cases (4 florid and 13 mild to moderate). In the 10 cases associated with malignancy, 9 had FNAC and was reported as malignant (C5) in 6 (67%) cases, highly suspicious (C4) in 2 (22%) cases and atypical (C3) in 1 (11%). False positive FNAC (C5) occurred in two patients, one of whom presented with pleomorphic microcalcifications suggestive of ductal carcinoma in situ. This patient was treated with a wire guided segmental mastectomy. All invasive tumours were less than 20 mm in size (T1) and of these 4 were grade I and 2 were grade II. Axillary dissection was performed in 4 patients none of whom had axillary node metastases. Our study demonstrates a significant incidence of malignancy associated with radial scars (31%) suggesting that radial scars may be premalignant lesions. This is supported by detecting various stages of mammary carcinogenesis (atypical epithelial hyperplasia, ductal carcinoma in situ, and early invasive malignancy) in these lesions. Fine needle aspiration cytology seems to be unreliable in the diagnosis of radial scar associated malignancy (67% sensitivity and 91% specificity). Stellate lesions, therefore, should be excised to obtain an histological diagnosis regardless of cytological findings. Further studies examining the biology of radial scars are required.