Synchronous occurrence of epithelial and stromal tumors in the stomach. Report of six cases

Objective.-The synchronous development of epithelial and stromal tumors in the stomach has been reported rarely in the literature. A series of 6 such cases is described in this article. Methods.-Clinical and pathologic data were recorded and the literature was reviewed. Results.-Five cases featured the simultaneous occurrence of stromal tumors (1 benign, 3 borderline, 1 malignant) and adenocarcinomas, whereas the stromal tumor in the sixth case was found in association with a carcinoid. No collision tumors were observed. In 2 cases, tumors arose from the same site and were closely juxtaposed, but in 4 patients they developed from different areas of the stomach. A preoperative histologic diagnosis of both tumors was not achieved in any case. Two patients harbored occult infiltrative epithelial lesions (1 diffuse-type adenocarcinoma, 1 carcinoid), which were detected only at pathologic examination of the gastric mucosa adjacent to the stromal tumor. Conclusions.-The simultaneous occurrence of epithelial and stromal tumors in the stomach can be less rare than usually expected. Coincidence alone could account for such an association, particularly in areas with high incidence rates of gastric cancer. The hypothesis that a single carcinogenic agent might interact with two neighboring tissues in the stomach inducing the development of tumors of different histotype cannot be theoretically discarded.