Most common type of malignancy of stomach is:September 2007

Ans. A: AdenocarcinomaGastric adenocarcinoma is a malignant epithelial tumor, originating from glandular epithelium of the gastric mucosa. Stomach cancers are commonly adenocarcinomas (90%).Histologically, there are two major types of gastric adenocarcinoma (Lauren classification): intestinal type or diffuse type. Adenocarcinomas tend to aggressively invade the gastric wall, infiltrating the muscularis mucosae, the submucosa, and thence the muscularis propria.Intestinal type adenocarcinoma tumor cells describe irregular tubular structures, harboring pluristratification, multiple lumens, reduced stroma ("back to back" aspect). Often, it associates intestinal metaplasia in neighboring mucosa. Depending on glandular architecture, cellular pleomorphism and mucosecretion, adenocarcinoma may present 3 degrees of differentiation: well, moderate and poorly differentiate.Diffuse type adenocarcinoma (mucinous, colloid, linitis plastica, leather-bottle stomach) Tumor cells are discohesive and secrete mucus which is delivered in the interstitium producing large pools of mucus/colloid (optically "empty" spaces). It is poorly differentiated. If the mucus remains inside the tumor cell, it pushes the nucleus at the purpley"signet-ring cell".Around 5% of gastric carcinomas are lymphomas (MALTomas, or MALT lymphoma).Carcinoid and stromal tumors may also occur.