vascular lesions of the small intestine and colon are common causes of acute or chronic gastrointestinal hemorrhage , and arteriovenous malformations ( avms ) are an important vascular cause of obscure and intermittent gastrointestinal bleeding ( 1 ) .
histologically , avms are persistent communications between thick - walled arteries and veins without intervening capillaries and are divided into true or congenital and acquired forms according to their locations and age at their presentations .
although the endoscopic appearances of avms occurring in gastrointestinal tracts are not distinctive , some reported cases were observed as flat or mildly elevated hemorrhagic spots or erosions , while others have been appeared as polypoid masses .
avms are usually small , single , and are located mainly in the rectum and descending colon in case of congenital or true avms , unlike acquired avms which are located mainly within the right colon .
avms are relatively uncommon in the small bowel , and it is extremely rare that they present as a circumferential , transmural , and dilated vascular structure encasing only the terminal ileum and mimicking intestinal varicosis .
we report a rare case in which a transmural avm mimicking intestinal varicosis and encasing the terminal ileum circumferentially .
a 30-yr - old man was transferred to our hospital for the investigation and management of intermittent hematochezia for a 5-yr duration . on admission ,
he was not being prescribed a nonsteroidal anti - inflammatory drug , nor was suffering from portal hypertension or liver disease .
there was no history of a peptic ulcer , and examinations of skin , oral , and anal mucosa revealed no abnormal findings .
subsequent colonoscopy revealed a circumferential erythematous , nodular , and elevated lesion with hematocystic spots in the terminal ileum resembling varicosis ( fig .
1 ) . computed tomography ( ct ) scans with 3-dimensional angiographic reconstruction showed a vascular tuft located around the terminal ileum ( fig .
2 ) . to exclude other synchronous intraluminal sources of bleeding in the small bowel we performed enteroclysis , which revealed a segmental , nodular , and uneven elevated lesion with a length of 10 cm in the terminal ileum ( fig .
the patient was treated by ileocecectomy , which encompassed the nodular and dilated vascular structure in the terminal ileum that resembled a varicosis lesion on gross inspection ( fig .
4 ) . surgical biopsy specimens revealed dilated vascular channels with a thickened wall involving the entire bowel wall and secondary arterialization of veins consistent with an avm ( fig . 5 ) .
his postoperative course was uneventful , and the patient has been followed - up without a further episode of hemorrhage .
despite dramatic improvements in diagnostic and therapeutic modalities , it is not always possible to determine the appropriate diagnosis and treatment for vascular lesions , such as , vascular ectasia , hemangiomas , dieulafoy lesions , and avms . in particular in the case of avms
, no distinctive endoscopic or radiologic appearance has been elucidated because of their rarity , terminologic inconsistencies , and the diverse natures of their endoscopic morphologies .
the presented case describes an unusual avm that involved the full thickness of the terminal ileum , mimicking intestinal varicosis on endoscopic and gross inspection .
endoscopic finding of our case which demonstrates dilated and tortuously distended vascular tufts with red markings is a typical feature of intestinal varicosis ( 2 , 3 ) .
the majority of avms reported are focal , flat , or mildly elevated with erythematous spots or erosions , and a minority of avms have polypoid or pedunculated masses ( 4 - 6 ) .
a medline search revealed that only a small proportion of avms mimic intestinal varicosis with transmural involvement of the small and/or large bowel , and no endoscopic pictures were provided ( 7 - 9 ) .
we found only one case of an avm with complete endoscopic pictures and gross pictures of dilated , tortuous , vascular tufts similar to our case .
it involved the entire colon without displaying a vascular texture by angiography ( 10 ) .
although avms can occur in jejunum ( 11 ) , the most common sites of involvement of true congenital avms are the rectum or sigmoid colon .
many reports have suggested that they are most common in the cecum and ascending colon , but the terminologic confusion concerning the differentiation of angiodysplasia and acquired avms , which mainly develop in right colon , from congenital avms may have influenced the results .
true avms are developmental and mainly occur in the rectum or sigmoid colon of patients younger than 50 yr , and correspond to type 2 lesions according to moore 's classification ( 12 ) .
acquired avms or angiodysplasia correspond to type 1 according to this classification and occur in patients older than 50 yr .
avms in younger patients tend to occur at atypical sites such as in the small bowel , but no segmental form of avm has been previously reported to involve only the terminal ileum in a cylindrical manner .
the usefulness of ct for the detection of sources of gastrointestinal bleeding has been recently described in the context of imaging modality developments ( 13 ) . in the present case
, we performed ct with a 3-dimensional angiographic reconstruction instead of conventional mesenteric arterial angiography because we did not consider invasive radiological therapeutic intervention as a potential elective hemostatic modality , and because we required an evaluation of the relation between the vascular architecture and the bowel wall .
ultimately , surgical resection offers the best chance of curative treatment in such situations . in conclusion
, we experienced a rare case of a segmental transmural avm involving the terminal ileum and mimicking intestinal varicosis , which presented as a case of recurrent lower gastrointestinal hemorrhage , and which was successfully treated by surgical resection .
 we report on an exceptional vascular cause of gastrointestinal hemorrhage . a 30-yr - old man was admitted because of recurrent hematochezia . 
 colonoscopy showed circumferential , erythematous , and nodular vascular distensions with hematocystic spots in the terminal ileum resembling varicosis and subsequent computed tomography with 3-dimensional angiographic reconstruction revealed a vascular architecture around the terminal ileum . 
 no other potential source of bleeding was identified . 
 the patient was treated by ileocecectomy and the final diagnosis was of an arteriovenous malformation confined to the terminal ileum . 
 he has been followed - up without a further hemorrhagic episode . 