A usually aggressive, poorly differentiated invasive adenocarcinoma characterized by the presence of malignant glandular cells in which the nucleus is pressed to one side by the presence of intracytoplasmic mucus. It may arise from the stomach, small and large intestine, ampulla of Vater, appendix, gallbladder, pancreas, lung, bladder, breast, and prostate gland. The disease is MONDO_0005092 (signet ring cell carcinoma). Also known as: signet ring carcinoma, signet ring carcinoma NOS (morphologic abnormality), signet ring cell adenocarcinoma, signet ring cell carcinoma (morphologic abnormality).