Pathology of R4 spiculated lesions in the breast screening programme.

Small spiculated carcinomas are indistinguishable from benign radial scar/complex sclerosing lesions on mammography, leading to a radiological assessment of R4 (suspicious, probably malignant). The cytological and pathological features of 80 screen detected R4 spiculated lesions were reviewed. The analysis showed that there were 46 radial scars, of which 38 were benign and 8 (17%) contained foci of ductal carcinoma in situ (DCIS), and 34 spiculated carcinomas. The majority of radial scars showed some degree of epithelial hyperplasia (assessed semi-quantitively) but the cellularity of the lesion as a whole was not related to the presence of DCIS. In 20 cases no aspiration was attempted for cytology but 40% were inadequate and only one lesion containing DCIS had cytology C4 or C5. Diagnosis of radial scar was made in all cases by localization biopsy. The carcinomas ranged in size between 4 and 15 mm (mean 8.9 mm) and were of grade 1 (21 = 63%) or grade 2 (12 = 37%). There were 16 infiltrating ductal carcinomas of no special type, 12 tubular carcinomas, three lobular carcinomas, two ductal and lobular mixed, and one mucinous carcinoma. Only one patient with carcinoma was node-positive. For the carcinomas, 12 (35%) yielded C5 (malignant) cytology allowing pre-operative diagnosis.