Pathology of Gangrene

Pathological features of gangrene are described. Gangrene is commonly caused by infection of anaerobic bacteria. Dry gangrene belongs to noninfectious gangrene. The hypoxic/ischemic condition accelerates the growth of anaerobic bacteria and extensive necrosis of the involved tissue. Clostridial and non-clostridial gangrene provokes gas formation in the necrotic tissue. Acute gangrenous inflammation happens in a variety of tissues and organs, including the vermiform appendix, gallbladder, bile duct, lung, and eyeball. Emphysematous (gas-forming) infection such as emphysematous pyelonephritis may be provoked by Escherichia coli and Klebsiella pneumoniae. Rapidly progressive gangrene of the extremities (so-called “flesh-eating bacteria” infection) is seen in fulminant streptococcal, Vibrio vulnificus, and Aeromonas hydrophila infections. Fournier gangrene is an aggressive and life-threatening gangrenous disease seen in the scrotum and rectum. Necrotizing fasciitis is a subacute form of gangrene of the extremities. Of note is the fact that clostridial and streptococcal infections in the internal organs may result in a lethal hypercytokinemic state without association of gangrene of the arms and legs. Uncontrolled diabetes mellitus may play an important role for vulnerability of the infectious diseases. Pseudomonas-induced malignant otitis externa and craniofacial mucormycosis are special forms of the lethal gangrenous disorder.