This 51-year-old woman with a history of ulcerative colitis, perforated diverticulitis, episcleritis developed red to violaceous tender fluctuant nodules on her legs. Many lesions ruptured and drained sterile seropurulent fluid. She developed a persistently fever and elevated white blood count with a left shift. Numerous blood cultures, urine cultures, and chest X-rays failed to show a source of infection. Biopsies of the leg lesions showed a dermal abscess with overlying mixed and acute chronic inflammation. A second biopsy showed mixed lymphocytic and neutrophilic dermatitis. A third biopsy showed a subcorneal pustular dermatosis. All of these findings were felt to be consistent with pyoderma gangrenosum or an infection, but special stains and cultures revealed no evidence of infection with bacteria, acid fast bacilli or fungi. She improved after 3 days of intravenous immunoglubulin at 35 grams per dose.
