Giant leiomyosarcoma of the rectum. Report of a case and review of 122 surgically treated cases of rectal leiomyosarcomas in Japan

Rectal leiomyosarcoma (RLS) is rare and represents a serious challenge to both pathologists and surgeons as far as the difficulty in differentiation from leiomyoma and selection of the optimal mode of surgical or other therapies are concerned. In this report a case of RLS in which a preoperative biopsy diagnosis of leiomyoma was revised to leiomyosarcoma based on the information added by various imaging modalities is presented. This appears to be the first English report of RLS in which MRI-CT and angiography are used concomitantly. Suth an approach is crucial in order to define the malignant characteristics of the tumour, and to detect the organ of origin, extent of invasion and distant spread. We also review the Japanese literature and discuss the natural behaviour, diagnostic and therapeutic aspects of this uncommon tumour in the light of 122 cases of RLS reported in Japan. Two striking points deserve emphasis: 1) the high rate of diagnostic inaccuracy (34%) and false leiomyoma diagnosis (26%) in preoperative biopsies; 2) the unexpectedly high rate of local lymphatic metastasis (16%) during primary surgery. We think that an aggressive diagnostic and therapeutic approach to RLS offers a chance of better survival and seems justifiable.