eP525 - A Rare Case of Refractory Left Sided Colitis Due to Idiopathic Myointimal Hyperplasia of the Mesenteric Veins (IMHMV)

Purpose/Background: Idiopathic myointimal hyperplasia of the mesenteric veins (IMHMV) is a rare cause of chronic colonic ischemia with less than 300 cases reported in the literature since it was first described in 1991. IMHMV is commonly mistaken for inflammatory bowel disease (IBD) or ischemic colitis and patients typically experience months to years of debilitating diarrhea and abdominal pain before diagnosis and surgical management. We present a case of a 67 year-old man who presented with a 6 month history of abdominal pain and altered bowel habits that was diagnosed on surgical pathology.Methods/Interventions: A 67 year-old male initially presented to his family physician with complaints of new onset of severe abdominal pain and irregular bowel movements for 4 months after initiation of GLP-1 agonist for weight loss and diabetes mellitus. His physical exam was unremarkable. He had an unrevealing biochemical evaluation and GI infectious evaluation was unrevealing. Computed tomography (CT) of the abdomen and pelvis showed normal vasculature and nonspecific colitis from the mid-transverse colon to anorectal junction. Colonoscopy revealed confluent inflammation consistent with ischemia present from the distal rectum to mid transverse colon. Pathology revealed non-specific inflammation consistent with ischemia. He was treated with antibiotics and corticosteroids without clinical benefit. Due to refractory symptoms, he underwent an extended left colectomy and colostomy.Results/Outcomes: The patient underwent open extended left colectomy with end colostomy formation. Intraoperative findings revealed severe left sided colonic inflammation and wall thickening. Pathology revealed severe mucosal inflammation and myointimal hyperplasia of the mesenteric veins with arterial sparing. His postoperative course was uncomplicated with no recurrence of his initial presenting symptoms at 3-month follow up.Conclusion/

Discussion: IMHMV is a rare cause of colonic ischemia with poorly understood pathophysiology which most commonly presents in elderly men with left sided distribution including the rectum. Diagnosis of IMHMV should be considered in the setting of atypical findings for ischemic colitis in the appropriate population. Prompt recognition of IMHMV can lead to earlier definitive surgical management and avoid unnecessary morbidity.Gross sample, Histologic slide, and Endoscopic findings of IMHMVA- Descending colon and proximal rectum with firm epiploic appendages
B- VVG stain of mesenteric veins with no stain of the elastic layer, indicating abnormally thickened veins
C- Rectosigmoid and D- descending colon on endoscopy with altered vascular pattern and pale, congested, friable mucosa