[Extramammary myofibroblastoma affecting the pelvic region: a case report].

Mammary myofibroblastoma is a rare soft-tissue tumor. Extramammary myofibroblastomas are particularly rare. We here report the case of a 78-year-old man presenting with pelvic pain relieved by defecation or urination. Rectal examination showed a mass in front of the anterior rectal wall. The magnetic resonance imaging (MRI) showed a well-circumscribed and heterogeneous mass measuring 10 x 6 x 8cm located behind the bladder which was pushed forward in front of the rectosigmoid. Immunohistochemical analyses showed diffuse co-expression on CD34 cells and desmin, Rb expression on most cells, oestrogen receptor expression, intense and diffuse P16 expression and a ki67 proliferation index of 25%. The patient had no recurrence 8 months after radiotherapy followed by surgery. Breast myofibroblastoma is a rare and benign tumor. Recurrence is hardly observed after local treatment. This study highlights the supporting role of radiotherapy in the efficacy of surgery.