Pyoderma gangrenosum is a chronic, neutrophilic, progressive skin necrosis of unknown etiology often associated with systemic illness.
Etiology is unknown, but pyoderma gangrenosum can be associated with various systemic illnesses, including vasculitis, gammopathies, RA, leukemia, lymphoma, hepatitis C virus infection, SLE, sarcoidosis, polyarthritis, Behçet disease, hidradenitis suppurativa, and especially inflammatory bowel disease. It is thought to be mediated by an abnormal immune response. Most patients are age 25 to 55. It can manifest in various subtypes.
Pathophysiology is poorly understood but may involve problems with neutrophil chemotaxis. IL-8 is overexpressed in lesions. Ulcerations of pyoderma gangrenosum occur after trauma or injury to the skin in about 30% of patients; this process is termed pathergy.
Symptoms and Signs
Most often, pyoderma gangrenosum begins as an inflamed erythematous papule, pustule, or nodule. The lesion, which may resemble a furuncle or an arthropod bite at this stage, then ulcerates and expands rapidly, developing a swollen necrotic base and a raised dusky to violaceous border. An undermined border (ie, loss of underlying support tissue at the border) is common, if not pathognomonic. Systemic symptoms such as fever and malaise are common. The ulcers can coalesce to form larger ulcers, often with cribriform or sieve-like scarring. Symptoms and signs can vary with the subtype:
Pyoderma gangrenosum can also develop at other sites, such as around a stoma in patients who have inflammatory bowel disease (peristomal pyoderma gangrenosum), on the genitals (genital pyoderma gangrenosum), or in sites other than the skin, such as the bones, cornea, CNS, heart, intestine, liver, lungs, or muscle (extracutaneous pyoderma gangrenosum).
Diagnosis is clinical and is a diagnosis of exclusion after other causes of ulceration have been ruled out. Expansion of ulceration after surgical debridement strongly suggests pyoderma gangrenosum. Biopsies of lesions are not often diagnostic but may be supportive; 40% of biopsies from a leading edge show vasculitis with neutrophils and fibrin in superficial vessels. Patients who have bullous (atypical) pyoderma gangrenosum should be monitored with periodic clinical assessment and CBC for development of a hematologic disorder.
Would healing can be promoted with wound care that includes moisture-retaining occlusive dressings for less exudative plaques and absorptive dressings for highly exudative plaques. Wet-to-dry dressings should be avoided. Topical therapy with high-potency corticosteroids or tacrolimus can help with superficial and early lesions. For more severe manifestations, prednisone 60 to 80 mg po once/day is a common first-line therapy. TNF-α inhibitors (eg, infliximab, adalimumab, etanercept) are effective, particularly in patients who have inflammatory bowel disease. Cyclosporine 3 mg/kg po once/day is also quite effective, particularly in rapidly progressive disease. Dapsone, azathioprine, cyclophosphamide, methotrexate, clofazimine, thalidomide, and mycophenolate mofetil have also been used successfully. Antimicrobials such as minocycline have also been used for vegetative (superficial) pyoderma gangrenosum. Surgical treatments are avoided because of the risk of wound extension.
Last full review/revision November 2013 by Wingfield E. Rehmus, MD, MPH
Content last modified November 2013