Pyoderma gangrenosum (PG) is an uncommon ulcerative cutaneous condition of uncertain etiology. Pyoderma gangrenosum was first described in 1930. It is associated with systemic diseases in at least 50% of patients who are affected. The diagnosis is made by excluding other causes of similar appearing cutaneous ulcerations, including infection, malignancy, vasculitis, collagen vascular diseases, diabetes, and trauma. Ulcerations of pyoderma gangrenosum may occur after trauma or injury to the skin in 30% of patients; this process is termed pathergy.The 2 primary variants of pyoderma gangrenosum are the classic ulcerative form, usually observed on the legs, and a more superficial variant known as atypical pyoderma gangrenosum that tends to occur on the hands.
It is characterized by the presence of 1 or more ulcerations that are typically violaceous with an undermined border. Diagnosis is clinical and dependent on the exclusion of other causes of cutaneous ulceration. No specific pathologic or laboratory findings exist. Concurrent systemic disease occurs in 50% of affected patients. Commonly associated conditions include inflammatory bowel disease, arthritis, and hematologic malignancy. The remaining cases are considered autoimmune or idiopathic
In most of these cases the lesions were related to previous surgical interventions, probably as the result of a pathergy phenomenon. The main differential diagnoses were skin and soft tissue infections including necrotizing fasciitis, and malignant neoplasms. Negative initial wound cultures and the relative sparing of nipple/areola complex helped to eliminate these disorders.
Topical therapies include gentle local wound care and dressings, superpotent topical corticosteroids, cromolyn sodium 2% solution, nitrogen mustard, and 5-aminosalicylic acid. The new topical immune modifiers tacrolimus and pimecrolimus may have some benefit in certain patients.Systemic therapies include corticosteroids, cyclosporine, mycophenolate mofetil, azathioprine, dapsone, tacrolimus, cyclophosphamide, chlorambucil, thalidomide, tumor necrosis factor-alpha (TNF-alpha) inhibitors, and nicotine.Intravenous therapies include pulsed methylprednisolone, pulsed cyclophosphamide, infliximab, and intravenous immune globulin.Other therapy includes hyperbaric oxygen.
Surgery should be avoided, if possible, because of the pathergic phenomenon that may occur with surgical manipulation or grafting, resulting in wound enlargement. In some patients, grafting has resulted in the development of pyoderma gangrenosum at the harvest site. In the cases in which surgery is required, the best plan, if possible, is to have the patient on therapy in order to prevent pathergy.