Smooth muscle tumors of the alimentary tract.

Smooth muscle tumors (SMT) of the alimentary tract are uncommon. A series of 32 cases (16 leiomyomas and 16 leiomyosarcomas) are presented. The most common presenting clinical signs are bleeding or obstruction. These are caused mainly by degenerative changes within the lesion or its enlargement. The endoluminal SMT cause symptoms early and are more easily detectable. However, the extraluminal SMT, producing an extrinsic mass, can remain asymptomatic for a long time. Thus, such SMT may be found incidentally during operation. The larger SMT are mostly malignant. Microscopically it is sometimes difficult to determine if the SMT is benign or malignant.