Incidental finding of diffuse cavernous rectal haemangiomatosis during bowel cancer screening.

Background: This case seeks to highlight to endoscopists a rare benign disorder that may be encountered during endoscopy. Clinicians may be tempted to biopsy, which could lead to a catastrophic gastrointestinal haemorrhage.

Case Presentation: A 66-year-old asymptomatic Caucasian male was referred for colonoscopy with a positive faecal occult blood test as part of the UK national bowel cancer screening programme. Relevant past medical history included atrial fibrillation for which he took Dabigatran. He had a normal haemoglobin, mean cell volume, platelet and clotting function. During colonoscopy, an unusual vascular pattern encompassing the entire rectum extending to the rectosigmoid junction was noted at intubation. The lesion demonstrated confluent circumferential purple discolouration indicating venous blood supply, with heaping up of the mucosa involving the entire rectum and rectosigmoid junction. There was no corresponding history of venothromboembolic disease or liver disease. The patient proceeded to have computed tomography (CT) which revealed a considerably thickened rectosigmoid wall with multiple small rounded punctate calcifications within it, and no other visceral involvement. Subsequent magnetic resonance (MR) scan of the pelvis demonstrated extensive diffuse thickening of the rectum and lower sigmoid with intermediate to high T2 signal, and an internal architecture of multiple 'grapelike' lobulations.

Conclusion: The findings were consistent with diffuse cavernous haemangiomatosis of the rectum (DCHR), an extremely rare benign submucosal vascular intestinal tumour originating from the dentate line. Misdiagnosis of DCHR is common and the macroscopic appearance of DCHR can mimic varices, haemorrhoids, polyps or proctitis. MR imaging is the gold standard for diagnosis. Common presentation is with haematochezia due to mucosal wall erosion. The treatment of choice for symptomatic DCHR is pull-through transection and colo-anal anastomosis. This case seeks to highlight a rare disorder that can be encountered incidentally during lower GI endoscopy. Injudicious biopsy is potentially catastrophic. In a patient who endoscopically has evidence of a DCHR, we advocate MR pelvis assessment to clarify the nature of the lesion to guide future management if required. The patient discussed remains well, asymptomatic, with no evidence of iron deficiency anaemia.