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Pyoderma gangrenosum
is a chronic progressive skin necrosis of unknown etiology often associated
with systemic illness.
Etiology is unknown, but pyoderma gangrenosum can be associated with vasculitis, gammopathies, RA, leukemia, lymphoma, hepatitis C, SLE, sarcoidosis, and especially inflammatory bowel disease and is thought to be due to an abnormal immune response.
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 is common, if not pathognomonic. Systemic symptoms such as fever, malaise, and arthralgias are common. The ulcers coalesce to form larger ulcers, often with cribriform or sieve-like scarring. A well-known feature is pathergy, wherein new lesions develop at sites of trauma. This has parallels to the Koebner phenomenon in psoriasis.
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. Prednisone 60 to 80 mg po once/day is still the mainstay of treatment, although cyclosporine 3 mg/kg/day po is also quite effective. Dapsone , clofazimine, thalidomide , infliximab , and mycophenolate mofetil have also been used successfully.
Last full review/revision November 2005
Content last modified November 2005
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