Retroperitoneal metastatic adenocarcinoma complicated with necrotizing fasciitis of the thigh in a patient with advanced rectal colon cancer.

Background: Necrotizing fasciitis of the thigh due to colon cancer has not been previously reported, especially during radiotherapy. Case Presentation: A 73-year-old woman admitted to our hospital was diagnosed with sigmoid colon cancer that had spread to the left psoas muscle; radiotherapy was performed. Three months after the initiation of radiotherapy, the patient developed gait disturbance, poor appetite and high fever and was therefore admitted to the emergency department of our hospital. Blood examination revealed generalized inflammation with a high white blood cell count and C-reactive protein level. Computed tomography of the abdomen revealed fluid and gas tracking from the retroperitoneum into the intramuscular plane of the grossly enlarged right thigh. Consequently, emergent debridement was not performed and conservative therapy was done. The patient died. Conclusion: Necrotizing fasciitis of the thigh due to the spread of rectal colon cancer is unusual, but this fatal complication should be considered during radiotherapy in patients with unresectable colorectal cancer.