Leiomyosarcoma of the rectum: a case report.

A case of leiomyosarcoma of the rectum is reported. Repeated biopsies of the tumour had failed to reveal evidence of malignancy. Only after radical excision of the rectum had been performed and the entire tumour had been submitted to histological examination was the clinical impression of malignancy confirmed. The difficulties in the histological differentiation of simple from malignant smooth-muscle tumours of the rectum are discussed. The clinical features on which a diagnosis of malignancy can be made are described.