What is Pyoderma Gangrenosum?

Pyoderma gangrenosum (PG) is a rare cause of skin ulcers that belongs to a group of conditions called neutrophilic dermatoses. These conditions happen when a type of white blood cell, called a neutrophil, builds up in the skin and causes inflammation. The name “Pyoderma Gangrenosum” can be confusing. It may sound like gangrene, a condition where tissue dies due to lack of blood supply, but they are not the same thing. The term comes from old medical language. “Pyo” means pus, “derma” means skin, and “gangrenosum” refers to tissue breakdown. PG is not caused by infection and cannot be spread from one person to another.

There are five recognized subtypes of PG: 

Classic PG: This is the most common subtype. It typically presents as a rapidly progressive painful ulcer with a red edge where the skin slightly overhangs the wound. This edge can make the ulcer look smaller on the surface than it really is, since the ulcer often extends underneath the skin.

Peristomal PG: This subtype is most often seen in the context of patients with stomas and inflammatory bowel disease. 

Vegetative PG/Superficial granulomatous PG: This rare subtype is often more superficial, and the lesions appear wart-like.

Bullous PG: This rare subtype presents as rapidly evolving, superficial blisters most often appearing on the arms.

Pustular PG: This rare subtype presents as painful pustules that do not develop into ulcers.