Schistosoma mekongi infection in a leiomyosarcoma of the small bowel: a case report.

We report a fortuitous occurrence of a small bowel leiomyosarcoma infected with Schistosoma mekongi in an elderly patient from Kampuchea. S mekongi is endemic in countries along the lower Mekong River basin (Laos, Thailand, and Kampuchea), where its intermediate snail hosts (Lithoglyphopsis aperta) are found. The diagnosis was made by examining the numerous ova that were embedded in the tumor and along the small bowel wall. The ova with their small lateral spines are easily confused with those of Schistosoma japonicum, but are consistently smaller and round. The patient presented with lower gastrointestinal bleeding secondary to tumor invasion of the small bowel rather than from heavy parasitic infection. Because of the spindle-cell morphology of the tumor, an exuberant fibroblastic host reaction to the ova was considered during frozen section examination. Unlike the more common species of schistosoma (eg, Schistosoma mansoni and Schistosoma haematobium) that are associated with the development of malignant neoplasms, we believe our case represents a chance finding and that the possible role of S mekongi infection in the neoplastic process is unlikely.