[A case of double primary cancer: early gastric adenocarcinoma associated with adenocarcinoma and carcinoid].

Carcinoid tumors show variety of pathological features and some of them are admixed with adenocarcinoma. The carcinoma-carcinoid spectrum is a concept of classifying tumors based on the tumor mass differentiation which is composed of tissues of both endocrine and nonendocrine functions. When two types of tissues exist within one tumor intermingled with each other in a similar proportion, it is called composite tumor. On the other hand, collision tumor is characterized by the presence of two localized tissue types adjacently together. Gastric composite tumors are relatively rare. According to the reports on the Korean literature, there are several collision tumors, but only one case of gastric composite tumor has been cited. Reports of multiple synchronous or metachronous cancers have increased steadily during the last decades. Multiple gastric carcinoids or carcinoid tumors developed in association with gastric adenocarcinoma contribute to this trend. We report one case of gastric composite tumor simultaneously occurring with a early gastric adenocarcinoma with review of the literature.