Etymology
The etymology of gangrene derives from the Latin word gangraena and from the Greek gangraina (γάγγραινα), which means "putrefaction of tissues". It has no etymological connection with the word green, despite the affected areas turning black, green, or yellowish brown. References
External links

 Media related to Gangrene at Wikimedia Commons
Radiation proctitis or radiation proctopathy is condition characterized by damage to the rectum after exposure to x-rays or other ionizing radiation as a part of radiation therapy. Radiation proctopathy may occur as acute inflammation called "acute radiation proctitis" (and the related radiation colitis) or with chronic changes characterized by radiation associated vascular ectasiae (RAVE) and chronic radiation proctopathy. Radiation proctitis most commonly occurs after pelvic radiation treatment for cancers such as cervical cancer, prostate cancer, bladder cancer, and rectal cancer. RAVE and chronic radiation proctopathy involves the lower intestine, primarily the sigmoid colon and the rectum, and was previously called chronic radiation proctitis, pelvic radiation disease and radiation enteropathy. Signs and symptoms
Acute radiation proctopathy often causes pelvic pain, diarrhea, urgency, and the urge to defecate despite having an empty colon (tenesmus). Hematochezia and fecal incontinence may occur, but are less common. Chronic radiation damage to the rectum (>3 months) may cause rectal bleeding, incontinence, or a change in bowel habits secondary. Severe cases may lead to with strictures or fistulae formation. Chronic radiation proctopathy can present at a median time of 8-12 months following radiation therapy. Histopathology
Acute radiation proctopathy occurs due to direct damage of the lining (epithelium) of the colon. Rectal biopsies of acute radiation proctopathy show superficial depletion of epithelial cells and acute inflammatory cells located in the lamina propria. By contrast, rectal biopsies of RAVE and chronic radiation proctopathy demonstrates ischemic endarteritis of the submucosal arterioles, submucosal fibrosis, and neovascularization.