Pathergic pyoderma gangrenosum in a venous ulcer

A 74‐year‐old woman was referred to our department in December 1999 for a pyoderma gangrenosum (PG) arising at the edges of chronic leg ulcer. The history was positive for benign monoclonal gammopathy, ischemic hypertensive cardiopathy, polyarthrosis and venous lower leg deficiency. Monoclonal gammopathy of IgA Kappa type was diagnosed 10 years before with a continued benign nature. In 1990 a post traumatic PG of the left leg was diagnosed and a therapy with Cyclosporine A was started with healing of the lesion.In June 1999, 6 months before the hospitalization, a typical venous ulcer of the right leg appeared and was treated with bed‐rest, compression bandaging and topical desloughing therapy. In the last month, after a minor surgical debridement of the wound, the lesion developed pustules evolving into a painful, necrotic ulcer with ragged, purple‐red, undetermined borders (Fig. 1). A relapse of PG was suspected.Pyoderma gangrenosum involving the leg. An arrow indicates the site of the original chronic venous ulcerimageHistological examination was consistent with pyoderma gangrenosum and showed massive neutrophilic infiltration, hemorrhage and necrosis of the overlying epidermis. Wound culture was negative. Other laboratory examinations only showed IgA = 8.15 g/L. Investigation of other underlying medical conditions were normal or negative.The venous leg ulcer gradually healed with antiseptic and compression‐bandage therapy. After a 4‐month course of topical steroid therapy with good results, the PG recurred also involving the proximal area of the leg. Metilprednisolone 50 mg/day was started. Healing began 10 days later and 2 months later the wound healed and epithelialized. Steroid was reduce to 5 mg daily for 4 months. No recurrence was seen when the drug was stopped.