Pyoderma gangrenosum (PG) is an ulcerating skin condition of unknown etiology. Immune dysregulation is thought to play a role.

There are four clinical types:
  • Ulcerative
  • Pustular
  • Bullous
  • Vegetative

The ulcerative type is the most common. Lesions often begin as small, painful papules at sites of trauma that can rapidly expand. The lower extremities are most commonly involved however, other locations such as the genitalia, oral cavity, and peristomal sites can be affected.
PG has no racial predilection and typically occurs in the fourth or fifth decade of life.

PG characteristically presents as ulceration surrounded by an “angry” purplish-red undermined border. The lesions heal in a characteristic atrophic, cribriform pattern. Half of the patients with PG have an associated medical condition, inflammatory bowel disease being the most common. The incidence of PG in patients with Crohn’s disease and ulcerative colitis is 5% and 1%, respectively. Leukemias, chronic active hepatitis, and rheumatoid arthritis have also been associated with PG.

The diagnosis is clinical and one of exclusion. A biopsy can help rule out other causes of ulceration but is not specific. Routine hematological, urine, and culture testing should be performed to rule out underlying systemic illness or infection. The differential diagnosis should also include other causes of skin ulceration, such as malignancy, vasculitis, and diabetes.

The treatment of small lesions involves wound care with gentle debridement, topical or intralesional corticosteroids; topical tacrolimus has also shown some benefit. Larger lesions often require systemic immunosuppressive therapy. Prednisone is usually the treatment of choice; however, cyclosporine, the sulfa class of medications, methotrexate, and mycophenolate mofetil have also been used successfully. There has been recent evidence supporting the use of infliximab for this condition. Surgery with grafting is usually avoided.