Colorectal cancer comes in many forms, including adenocarcinoma, leiomyosarcoma, lymphoma, melanoma, and neuroendocrine tumors. Adenocarcinoma is the most common type of colorectal cancer and has two subtypes, signet ring cell and mucinous. This article discusses signet ring cell adenocarcinoma.
What is an adenocarcinoma? "Adeno-" is a prefix that means "gland." In general, glands secrete things and are classified as endocrine or exocrine. Endocrine glands secrete things into the bloodstream, like hormones. Exocrine glands secrete things that go outside of the body, like mucus and sweat.
A carcinoma is a malignant tumor that starts in epithelial tissue. Put the two words together and you get "adenocarcinoma," which means a malignant tumor in epithelial tissue, specifically in a gland.
The term "signet ring cell" describes the appearance of the cancer. To look at cancer cells under a microscope, you have to stain and dehydrate them. Because signet ring cell adenocarcinomas have so much fat in them, once they're dehydrated, the nucleus gets pushed all the way over to one side. This makes the cell look kind of like a ring under the microscope. (View a picture of a signet ring cell.)
Signet ring cell adenocarcinomas are considered more aggressive than regular adenocarcinomas and are harder to successfully treat. The signet ring cell form is very uncommon and accounts for about 0.1 percent of all adenocarcinomas.
Other Types of Colorectal Cancer: Source: Buetow, Peter and Buck, James. "Colorectal Adenocarcinoma." RadioGraphics 15.1 (Jan. 1995). Archives of the AFIP. 5 Jul. 2006 [http://www.rsna.org/REG/publications/rg/afip/privateM/1995/0015/0001/0127/1.htm].