Therapeutics in Dermatology
A reference textbook in dermatology
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Pyoderma gangrenosum

26 September 2013, by MODIANO Ph. & YOUNG P.


The first specific clinical description of this chronic ulcerative dermatosis was made by Brocq, Clément and Simon in 1908. The term pyoderma gangrenosum, suggested in 1930 by Brunsting, O’Leary and Goeckerman, was then adopted by most dermatology schools. In 50 – 70% of cases, pyoderma gangrenosum is associated with an existing disease that it can sometimes unveil.



Epidemiology: This is a rare disease (two cases/year/million inhabitants) that predominates in females (76%) [4]. The age at which it usually develops is somewhere between 25 and 55 years, but it can strike at any age including during childhood.

Pathophysiology: This is currently not well understood.

Associations with other diseases (table II): This issue is certainly one of the most difficult to approach with patients. This is because in 50 to 70% of cases, pyoderma gangrenosum is associated with an underlying disease. This disease may precede pyoderma gangrenosum, but equally pyoderma gangrenosum can unveil or precede the associated disease. Usually, the course of the cutaneous lesions is independent from that of the underlying disease. These disease associations are the reason for the sometimes-extensive set of investigations that are offered to patients.

Genetic risks: Pyoderma gangrenosum is not currently reported to have any genetic component.

Social and professional consequences: In spite of the purulent nature of the lesions and the febrile presentation, it is useful to stress that the lesions are not contagious.

The process of pathergy (when lesions appear or reproduce in an area that has suffered a trauma) is found in between 5 and 20% of cases and it is the only factor involved in relapse that can be managed. It does sometimes require patients to change some of their habits or current treatments (for example, discontinuing sclerotherapy for varicose veins).


Table II Associated diseases.

Common comobidities

Rares comorbidities

Inflammatory gastrointestinal disorders (around one third of cases) 

Crohn’s disease

Ulcerative colitis

Colonic diverticulosis

Atrophic gastritis

Inflammatory rheumatic disorders


Seronegative polyarthritis

Rheumatoid arthritis

Felty’s syndrom


Immune system abnormalities


Monoclonal gammapathy,

mainly involving IgA (around 10% of cases)

Congenital or acquired hypogammaglobulinaemia

HIV infection

Hyper-IgE syndrome

Systemic lupus erythematosus

Haematological and neoplastic disorders (around 7% of cases)


Acute and chronic myeloid leukaemia



Cancers of the internal organs




Active chronic hepatitis

Behçet’s disease


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