Cellular leiomyomas of the stomach in 49 patients.

The cellular leiomyoma of the stomach is composed of tightly packed, generally uniform spindle cells arranged in palisades, whorls, or interdigitations. Although these neoplasms have been variably considered to arise from gastric smooth muscle or Schwann cells, the morphogenesis is incompletely resolved. Perhaps they derive from a multipotential gastric stromal stem cell that is capable of differentiating toward smooth muscle. A cellular gastric tumor composed of fairly uniform, elongated spindle cells is unlikely to be malignant. Of 49 such tumors, only one metastasized. The combination of an increased mitotic rate and large tumor size is possibly indicative of malignant potential.