When a wound is the harbinger of a serious underlying systemic illness

A 55-year-old woman presented with progressive enlarging and painful non-healing ulcers on her bilateral lower extremities; biopsy was consistent with pyoderma gangrenosum. Workup for an underlying illness revealed a cavitary lung nodule and an ulcerating mass in the anal canal. Patient did not have any respiratory or gastrointestinal symptoms. Differential diagnosis included inflammatory bowel disease, rectal carcinoma or infection such as tuberculosis, fungal process. Histopathology did not reveal any malignancy, inflammatory bowel disease or infection. Serological studies were positive for perinuclear antineutrophil antibodies specific to proteinase-3 antigen, and the patient was ultimately diagnosed with granulomatosis with polyangiitis. Intravenous pulse dose steroids were initiated followed by monthly pulse cyclophosphamide for 6 months, resulting in rapid and significant improvement of the wounds.