Yamashina M, Flinner R A
Am J Clin Pathol. 1985 Feb;83(2):233-6. doi: 10.1093/ajcp/83.2.233.
A morphologic curiosity is presented in a polypoid gastric tumor combined with adenocarcinoma and carcinoid tumor. It is likely that those two represent a composite tumor; however, the authors think it is more likely that they are two concurrent, independent collided tumors.