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A 22-year-old woman was referred with a 4-week history of bloody diarrhoea, tenesmus, abdominal and rectal pain. Prior to presentation, a prednisone taper had been initiated given suspicion for Crohn’s disease. Her medical history was otherwise unremarkable. Physical exam showed normal vital signs and mild left lower abdominal tenderness without peritoneal signs. Laboratory evaluation was significant for mild leucocytosis (white blood cell count 14.3×109/L (normal range 3.5–10.5×109/L)). CT scan of the abdomen/pelvis showed hazy mesenteric fat stranding, mural thickening, oedema and hyperenhancement involving the rectosigmoid colon with widely patent celiac and mesenteric vessels. Stool testing was negative for enteric pathogens. Flexible sigmoidoscopy revealed a 20 cm segment of purple-appearing mucosa involving the rectosigmoid with evidence of superficial ulcerations and exudate (figure 1A). Corresponding biopsies showed pink ‘hyalinised’ lamina propria, damage to the tops of crypts and fibrin thrombi in mucosal capillaries. Due to symptomatic persistence after 1 week of intravenous steroids and a single infusion of infliximab, surgical resection of the involved colonic segment with coloanal anastomosis was performed revealing circumferential thickening with ulcerated mucosa (figure 1B) and marked luminal narrowing by prominent myointimal smooth muscle hyperplasia of the mesenteric veins (figure 1C; arrow).
What is the most likely diagnosis based on the clinical presentation, endoscopic description and histological findings?
This clinical presentation including the described endoscopic features (figure 1A) and histological findings (figure 1C) are most consistent with colon ischaemia secondary to idiopathic myointimal hyperplasia of the mesenteric veins (IMHMV), a rare condition of unknown aetiology which was originally described by Genta et al.1
The presenting symptoms, endoscopic appearance and younger age of onset often associated with IMHMV closely mimic those of IBD. This case highlights a typical clinical scenario of IMHMV where endoscopic biopsies are usually non-diagnostic and IBD-directed medical therapy is unsuccessful, eventually leading to colonic resection.2 On histological review of the surgical specimen, evidence of luminal narrowing in mesenteric veins by myointimal hyperplasia (figure 1C; arrow) subsequently facilitates the distinction between IBD and IMHMV. To date, bowel resection appears to be curative in the setting of IMHMV without reports of recurrence.
In this case, colonic resection led to complete symptomatic resolution sustained after 1 year of clinical follow-up. On retrospective reflection, avoidance of immunosuppressive agents was possible as endoscopic biopsies did not support a presumptive diagnosis of IBD and instead exhibited features of ischaemic injury (figure 1B).
Contributors ZI: design, acquisition of data, and drafting of manuscript. BWA: drafting of manuscript and acquisition of data. SS: critical revision of the manuscript for important intellectual content and supervision.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
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