A case of idiopathic myointimal hyperplasia of the mesenteric veins presenting with small bowel obstruction.

Background: Idiopathic myointimal hyperplasia of the mesenteric veins (IMHMV) is a rare ischemic bowel disease with venous occlusion resulting from the proliferation of smooth muscles in the venous intima. In most patients, the disease affects rectosigmoid colon and causes persistent abdominal pain and hematochezia, which is similar to inflammatory bowel disease (IBD). In addition, it is difficult to make a precise diagnosis of IMHMV without surgery.

Case Presentation: An 81-year-old woman was admitted to our hospital with mild abdominal pain, nausea and vomiting. Repeated adhesive ileus was suspected due to the previous open and laparoscopic surgeries. Surgery was planned to treat small bowel obstruction. Intraoperatively no adhesive lesions were observed. However, a mass lesion was seen at the terminal ileum, which was suspected to have caused her bowel obstruction. Partial resection of the small intestine was performed. Macroscopic and histopathological examinations of the excised specimen showed circumferential ulceration with scarring, a thickened venous wall with active inflammation, and fibrotic changes that consequently produced stenosis and obstruction of the venous lumen in the subserosa. Additionally, Elastica van Gieson staining demonstrated thickening of the venous intima. The final diagnosis was IMHMV. At two years and 8 months after the operation, the patient was well without any additional medication.

Conclusion: IMHMV of the small intestine is rare. We described a case of IMHMV that was associated with ileus.