Primary signet ring cell carcinoma is a tumor most commonly located in the stomach, and less frequently in the breast, gallbladder, bladder, and pancreas. Primary signet-ring cell carcinoma of the colon and rectum is a rare form of adenocarcinoma of the large intestine, with a reported incidence of less than 1%.
Colorectal signet ring cell carcinoma has traditionally been associated with poor survival compared to mucinous adenocarcinoma and the more common adenocarcinoma.
Macroscopically, primary signet ring cell carcinoma of the colon and rectum shows the characteristic appearance of linitis plastica. Because symptoms often develop late, it is unfortunately usually diagnosed at an advanced stage.
Histologically, the tumor cells are arranged singly, in clusters and anastomosing cords. The intracellular mucin blob pushes the nucleus to one side, flattening it against the cytoplasmic membrane, and creates a signet ring appearance.
Patients with a signet ring cell carcinoma of the colon or rectum more often present with stage 3 or 4 disease than patients with adenocarcinoma, and signet ring cell carcinoma is also more commonly found in the proximal colon.
Signet ring cell carcinoma patients have a statistically signiﬁcant lower 5-year relative survival compared to mucinous and adenocarcinoma patients in both colon and rectal cancer patients. Patients who are treated with adjuvant chemotherapy have better survival rates than patients who do not receive adjuvant chemotherapy.
Signet ring cell carcinoma is an uncommon histological subtype of colorectal carcinoma, usually with a poor prognosis compared to mucinous and adenocarcinoma.
Stage III colonic signet ring cell carcinoma patients seemed to beneﬁt from adjuvant chemotherapy equally compared to AC in a national cohort study from the Netherlands.