Necrotizing fasciitis of the thigh secondary to radiation colitis in a rectal cancer patient.

Necrotizing fasciitis usually occurs after dermal injury or through hematogenous spread. To date, few cases have been reported as necrotizing fasciitis of the thigh secondary to rectal perforation in rectal cancer patients. A 66-year-old male complained of pelvic and thigh pain and subsequently developed necrotizing fasciitis in his right thigh. Four years earlier, he had undergone a low anterior resection and radiotherapy due to of rectal cancer. An ulcerative lesion had been observed around the anastomosis site during the colonoscopy that had been performed two months earlier. Pelvic computed tomography and sigmoidoscopy showed rectal perforation and presacral abscess extending to buttock and the right posterior thigh fascia. Thus, the necrotizing fasciitis was believed to have occurred because of ulcer perforation, one of the complications of chronic radiation colitis, at the anastomosis site. When a rectal-cancer patient complains of pelvic and thigh pain, the possibility of a rectal perforation should be considered.