Necrotizing fasciitis of the lower extremity secondary to a perforated rectosigmoid tumor

Necrotizing fasciitis (NF), which is a rare but life-threatening soft tissue infection, can present as a complication of colorectal diseases. The development of NF of the lower extremity secondary to a perforated colorectal tumor has been reported in only a few patients. We present a case of a 68-year-old woman, in which necrotizing soft tissue infection of the left lower extremity was the presenting feature of a perforated rectosigmoid tumor. On examination, there was a tender swelling and edema with palpable crepitus in the left inguinal region and thigh. Computed tomography showed gas within the retroperitoneal tissues, with subcutaneous edema and emphysema extending from the thigh to the ankle. NF was diagnosed, and the patient underwent Hartmann's procedure and fasciotomy with an aggressive debridement of the left thigh and inguinal region. In the case of NF of the lower extremity or abdominal wall without an obvious cutaneous source, an intraabdominal cause should be considered and sought.