Diffuse gastric cancer or signet ring cell canceris a type of cancer found most often in the glandular cells lining the stomach, but can also develop in the bowel, breast, pancreas, bladder, prostate or lung. The 2010 WHO (World Health Organization) classification recognizes four major histologic patterns of gastric cancers: tubular, papillary, mucinous and poorly cohesive (including signet ring cell carcinoma), plus uncommon histologic variants. The term "signet ring cell" is often used because the cells look like signet rings when viewed under a microscope. The signet cells are a type of epithelial cell. Epithelial tissue is skin tissue, covering and lining the body both inside and out. When diffuse gastric cancer is inherited it is called "hereditary diffuse gastric cancer." Treatment depends on the stage at which the cancer is found and may include chemotherapy, radiation therapy, or operations to remove the stomach (gastrectomy).