There are two major types of gastric adenocarcinoma:

• Intestinal.
• Diffuse.

Intestinal adenocarcinomas are well differentiated, and the cells tend to arrange themselves in tubular or glandular structures. The terms tubular, papillary, and mucinous are assigned to the various types of intestinal adenocarcinomas. Rarely, adenosquamous cancers can occur.

Diffuse adenocarcinomas are undifferentiated or poorly differentiated, and they lack a gland formation. Clinically, diffuse adenocarcinomas can give rise to infiltration of the gastric wall (i.e., linitis plastica).

Some tumors can have mixed features of intestinal and diffuse types.