There are three types of gangrene and they have different pathophysiology. 
A reduced arterial perfusion is observed in dry gangrene which results in the compensatory arteriolar dilation , which eventually results in distal edema, and damage of the endothelial tissue.  Saprogenic microorganisms such as Clostridium perfringens and Bacillus fusiformis are the most common organisms observed in wet gangrene which are responsible for infecting the tissues, thereby producing a putrid smell and edema.   Group A Steptococcus and exotoxins from Clostridium perfringens are responsible for the local and systemic infection found in gas gangrene.
Gangrene pathophysiology
Cellulitis pathophysiology
Lymphangitis pathophysiology
Fournier gangrene pathophysiology
Stevens-Johnson syndrome pathophysiology
Erysipelas pathophysiology
Gangrene laboratory findings
Thrombosis pathophysiology