Leiomyosarcoma of the rectum following pelvic irradiation: a difficult histological diagnosis.

Rectal leiomyosarcomas are very rare mesenchymal tumours. This is a case report of a rectal leiomyosarcoma diagnosed initially as a leiomyoma in a patient who had undergone pelvic radiotherapy several years previously. In addition to its pathological rarity, this case is of particular interest because it reinforces the association between pelvic irradiation and rectal leiomyosarcomas and it highlights the importance of treating suspicious cases aggressively in spite of favourable preoperative radiological and histological assessment.