• arteriovenous mesenteric fistula
• arteriovenous mesenteric malformation
• esophageal varices
• portal system occlusion
• transarterial embolization

Ischemic colitis with inferior mesenteric arteriovenous malformation (AVM) is a rare disease. Although a few reports have been published, no report has described the natural history of idiopathic mesenteric AVM.

A 50-year-old male was admitted to our hospital due to abdominal pain that had persisted for 3 mo and bloody diarrhea. He had no history of trauma or abdominal surgery. He had undergone two colonoscopies 6 mo and 2 years ago, and they showed only a polyp. He was diagnosed with ischemic colitis with inferior mesenteric AVM following contrast-enhanced abdominal computed tomography (CT) and underwent rectal low anterior resection. He has not had a recurrence of symptoms for 3 years. His history showed that he had undergone non-enhanced abdominal CT 2, 5, and 8 years ago when he had attacks of urinary stones. Retrospectively, dilation of blood vessels around the rectosigmoid colon could have been detected 5 years ago, and these findings gradually became more evident.

This is the first report of the natural history of inferior mesenteric AVM.

• Inferior mesenteric arteriovenous malformation
• Ischemic colitis
• Natural history
• Case report
• Arteriovenous malformation

Fistula formation is a severe adverse event related to antiangiogenetic agents such as bevacizumab and inferior mesenteric arteriovenous fistula (IMAVF) is a result of acquired factor, especially colon surgery. However, IMAVF occurs very rarely and there are few reports in patients during chemotherapy. We report a case of a patient who developed IMAVF during treatment with bevacizumab in metastatic colorectal cancer (mCRC) after colon surgery.

An 81-year-old man was diagnosed with descending colon cancer and underwent left hemicolectomy without any complications. He was definitely diagnosed with high-risk stage 2 and received tegafur-uracil plus leucovorin as adjuvant chemotherapy. Three years and 6 mo after the operation, the cancer relapsed with peritoneal dissemination. The patient underwent CyberKnife radiosurgery targeting the recurrent tumor and received chemotherapy with S-1 plus bevacizumab. At 1 year after chemotherapy, he complained of severe diarrhea, which is suspected drug-induced colitis. As diarrhea worsened despite the termination of treatment, he underwent colonoscopy and computed tomography (CT) scans that revealed edematous change from sigmoid to rectosigmoid colon. CT scans also revealed an aneurysm adjacent to the inferior mesenteric vein and multidetector CT angiography showed the IMAVF. Elective angiography confirmed the diagnosis of an IMAVF and it was successfully treated by arterial embolization. The patient resumed chemotherapy with only S-1 6 mo after embolization.

Clinicians should keep in mind the probability of severe diarrhea arose from IMAVF in mCRC patients treated with bevacizumab.

• Metastatic cancer
• Colon surgery
• Chemotherapy
• Fistula formation
• Inferior mesenteric artery
• Interventional radiology
• Case report

Visceral arteriovenous malformations (AVMs) are extremely rare with only a few cases described within the literature. To date, no cases of ischaemic colitis related to arteriovenous malformations affecting both superior and inferior mesenteric arteries have been reported. We report the first case of acute ischaemic colitis caused by venous congestion and reduced arterial flow due to combined AVMs in the territory of superior and inferior mesenteric arteries in a 51-year-old patient. After a multidisciplinary meeting, interventional radiology embolization was considered to be of unlikely benefit due to extensive varicosities; therefore, surgical treatment in the form of open subtotal colectomy and end ileostomy was performed. This case report demonstrates the severity and the complexity in the management of AVM-related ischaemic colitis, together with a review of the literature.

• arteriovenous malformation
• congestive
• ischaemic colitis
• mesenteric

Inferior mesenteric arteriovenous fistula (IMAVF) is a rare condition with 40 reported cases. It can be of congenital, idiopathic or acquired etiology. Acquired IMAVF occurs after trauma or has an iatrogenic origin due to abdominal interventions, mainly operations involving the left hemi-colon. A new case of iatrogenic IMAVF is described, which became symptomatic 13 years after right hemicolectomy and was diagnosed radiologically one year later. This case was treated successfully by means of endovascular arterial embolization. To our knowledge, this is only the second reported case of acquired IMAVF following right hemicolectomy.

• Inferior mesenteric artery
• arteriovenous fistula
• endovascular embolization
• ischemic colitis
• portal hypertension

• Gastric cancer
• Inferior mesenteric arterioportal fistula
• Interventional embolization
• Low anterior resection
• Portal hypertension
• Rectal cancer

Inferior mesenteric artery (IMA) and inferior mesenteric vein (IMV) fistulas or malformations are extremely rare, with only 36 cases reported. Low incidence and nonspecific clinical signs and symptoms make mesenteric arteriovenous fistulas difficult to diagnose. We describe a case of a primary IMA-IMV fistula. Our patient presented with severe portal hypertension and cardiomyopathy along with robust arteriovenous connections between the IMA and IMV. Arterial embolization in this patient had to be followed by venous embolization for successful resolution of portal hypertension and cardiomyopathy. This case also highlights that close outpatient monitoring for treatment failure and recurrence is necessary for this disease process.

• Amplatzer
• Arteriovenous fistula and malformation
• Embolization
• Inferior mesenteric artery
• Inferior mesenteric vein
• Portal hypertension