Benign biopsies in the prevalent round of breast screening: a review of 137 cases.

In the first round of the National Health Service Breast Screening Programme, 35,533 women attended for screening at the two breast screening units served by St Bartholomew's Hospital. Further assessment was necessary in 2212 women (6.2%), of whom 412 (1%) subsequently underwent surgical biopsy. Of these 137 had benign lesions. The predominant mammographic abnormality leading to biopsy was microcalcification in 55, a mass in 48, parenchymal asymmetry in 18 and architectural distortion in 16. Histology revealed fibrocystic change in 66, fibroadenoma in 27, radial scar/complex sclerosing lesion in 23, atypical ductal hyperplasia only in eight, and a variety of unusual benign lesions in 13. In an attempt to determine criteria which would minimize unnecessary biopsy of benign lesions in future, the mammographic and cytological features of these benign lesions were reviewed and compared with the final histology. The most common diagnostic problems were clustered and variable microcalcification, the radial scar/complex sclerosing lesion, and mammographic features shown to be atypical hyperplasia on histology.