Fibromatosis of the breast. A clinical and pathological study of 28 cases.

The clinical and pathologic findings of 28 examples of fibromatosis of the breast not involving the deep fascia or chest wall are reported. Five of the 20 lesions treated by local excision recurred. Recurrences developed within a 4 to 8 month period following surgery in four of the five instances, and 6 years after surgery in one instance. One lesion recurred five times over a period of 3 years. None of the patients died from their disease, and none developed a metastasis. Those lesions that recurred had been inadequately excised initially, since surgical margins showed fibromatosis. Specific histological features, such as size, cellularity, atypia, and mitotic figures, were not helpful in predicting recurrence. Although local excision appears to have been adequate in the majority (75%) of the patients, the infiltrative nature of fibromatosis necessitates documentation of tissue margins in order to avoid the possibility of recurrence. The differential diagnosis includes benign reactive processes (such as keloid and nodular fasciitis), fibrous histiocytoma, low-grade spindle-cell (metaplastic) carcinoma, and fibrosarcoma.