Desmoid-type fibromatosis of the breast: A case report.

Desmoid-type fibromatosis of the breast (also referred to as desmoid tumor or aggressive fibromatosis) is exceedingly rare. Although it does not metastasize, desmoid-type fibromatosisis is frequently locally aggressive. Recurrence is common (up to 35%), even after presumed total excision of the primary tumor [1]. The breast is an unusual location for the development of this tumor, with relatively few cases reported in the literature. We report a case of desmoid-type fibromatosis in the breast in a 31-year-old female who presented with a four-month history of a palpable left breast mass. Her imaging was discordant, so she underwent surgical excision of the mass. Multiple positive margins were present. She underwent re-excision to the level of the sternum medially. Final pathology showed a focally positive posterior margin, without muscle or fascial involvement. The patient's case was discussed at the multidisciplinary tumor board conference and no further intervention was recommended. To our knowledge, this is the first case report in the literature in which negative margins were unable to be achieved for desmoid tumors of the breast operatively.