A Case of Necrotizing Ischemic Colitis Suspected Being Induced by Schistosomal Ova Embolism

A 66-year-old man referred for lower right abdominal pain, and markedly elevated white blood cell count and CRP in blood tests was found in abdominal computed tomography (CT) to have an ascending colon lesion and ileocecal dilation 10 cm in diameter containing pneumatosis, and mesocolon swelling, necessitating semi emergency surgery based on a diagnosis of perforation of ascending colon carcinoma. Laparotomy disclosed a cecum dilated and greenly necrotic. A soft half-circular mass 60 mm in diameter was found at the anal side of Bauhin's valve. Right hemicolectomy was done based on a diagnosis of pericecal abscess and necrosis secondary to perforation by ascending colon cancer. Histological findings showed tubulovillous adenoma carcinoma of the ascending colon and ischemic colitis. Many calcified schistosomiasis japonica ova were seen in the veins in the submucosal cecal layer. These findings and the fact that the man had fished in a local Toyama river when young led to the pathogenesis of this case being identified as ischemic colitis caused by venostasis.