Fat necrosis of the breast following lumpectomy and radiation therapy for early breast cancer.

Between January 1980 and December 1985, 121 patients with early breast cancer were treated in the Department of Radiation Oncology at Westmead Hospital by external beam irradiation and an iridium wire boost following "lumpectomy". After a median follow-up of 26 months, 14 patients have developed recurrent masses in the treated breast. In four, recurrent carcinoma was strongly suspected and subsequently confirmed by fine needle aspiration biopsy, but in only two was a subsequent salvage mastectomy possible. The remaining 10 patients developed a nodule which was usually tender. With three exceptions, the nodule was at the primary tumour site and developed 4-43 months after treatment. In seven, tumour recurrence was suspected but not confirmed by biopsy and the other three were accepted as having post-treatment "radiation fibrosis". Excision biopsy was undertaken in eight of the 10 patients. Another patient underwent partial mastectomy for presumed local recurrence. The histological appearance in all cases was similar, with areas of fat necrosis and fibrosis with atypical stromal fibroblasts. Suture material was present microscopically in eight patients and was noted macroscopically (that is, by mammogram) in the one patient who did not undergo surgery. This complication is most likely caused by a combination of surgical and radiation factors. The difficulty in management is differentiation between tumour recurrence and a benign condition.