Necrotizing fasciitis from perforated sigmoid diverticulitis with subsequent pyoderma gangrenosum: a case report

Postsurgical pyoderma gangrenosum is a very rare form of cutaneous ulceration that is poorly recognized outside of dermatology and in some circumstances has been mistaken for necrotizing fasciitis. Here, we present a rare case of sigmoid diverticulitis with left ureter obstruction that perforated and quickly progressed into necrotizing fasciitis of the left buttock and leg via retroperitoneal spread in an immunocompetent patient. Nearly a year after intense surgical therapy, the patient rapidly developed ulcerating lesions over the left hip which presented a diagnostic dilemma. These were initially thought to represent Marjolin's ulcers, which would require aggressive local excision. Multiple diagnostic imaging tests and biopsies eventually confirmed pyoderma gangrenosum, which was successfully treated with immunosuppressive therapy. This case highlights the need for a very broad differential diagnosis and wide expertise consultation when managing unusual postsurgical complications, especially when treatment modality critically depends on the correct diagnosis.