gangrenous necrosis

Gangrenous necrosis is not a distinct histologic pattern but rather a clinical term describing necrosis of tissue, usually a limb or bowel, secondary to loss of blood supply (ischemia). It is subclassified into two forms: 1) Dry gangrene - results from coagulative necrosis due to chronic ischemia (e.g., peripheral arterial disease, atherosclerosis, diabetes). The tissue becomes dry, shrunken, and black due to denaturation of proteins and lack of bacterial invasion. Autoamputation may occur. 2) Wet gangrene - occurs when coagulative necrosis is complicated by bacterial superinfection, leading to liquefactive necrosis from neutrophilic enzymatic degradation. This produces a wet, boggy appearance with foul odor and risk of sepsis. Wet gangrene is a surgical emergency. Gas gangrene, a variant of wet gangrene, is caused by Clostridium perfringens, which produces alpha-toxin (a lecithinase) causing myonecrosis and gas production (crepitus on exam) within tissue. Clinically, gangrenous necrosis is commonly seen in diabetic foot ulcers, severe peripheral vascular disease, and bowel ischemia (e.g., strangulated hernia, volvulus, mesenteric ischemia). Management involves addressing the underlying vascular compromise, antibiotics for infected/wet gangrene, and surgical debridement or amputation when necessary. Distinguishing dry from wet gangrene is high-yield: dry = ischemia only, wet = ischemia + infection with high risk of systemic spread.