Sclerosing Mesenteritis

Sclerosing mesenteritis is the fibrotic stage of idiopathic mesenteric inflammation, with retractile fibrosis of the mesentery that may cause bowel kinking and obstruction.

• Along a spectrum: mesenteric lipodystrophy (fat necrosis), mesenteric panniculitis (inflammation), retractile mesenteritis (fibrosis).
• Rare; men are affected more than women, aged 50 to 70.
• Associations: IgG4 related disease (fibroinflammatory), abdominal surgery, autoimmune disease, malignancy, retroperitoneal fibrosis, Riedel thyroiditis, sclerosing cholangitis.
• Complications: small bowel obstruction, ischaemia from mesenteric vessel encasement, ureteric obstruction, chylous ascites, protein losing enteropathy.

• Chronic abdominal pain, nausea, vomiting, weight loss, early satiety, change in bowel habit, abdominal mass.
• Acute bowel obstruction in a minority, or incidental discovery.
• Systemic symptoms: fever, fatigue, night sweats.
• Features of extra abdominal IgG4 disease (pancreatitis, salivary gland swelling, thyroiditis).

• CT: mesenteric soft tissue mass or plaque of fibrosis, calcification, tethering and angulation of bowel loops, encasement of mesenteric vessels, retraction, lymph nodes, tumoral pseudocapsule.
• MRI/MR enterography: T2 hypointense fibrosis.
• Laboratory: CRP, ESR, serum IgG4, ANA, ANCA, albumin, lymphoma markers.
• Biopsy (image guided or laparoscopic) to confirm fibrosis with chronic inflammation and exclude lymphoma, desmoid tumour, carcinoid, GIST, lymphoma, tuberculosis. IgG4 immunostaining.
• PET CT may show uptake in active disease.

• Asymptomatic: observation with periodic imaging.
• Symptomatic or progressive: prednisolone 0.5 to 1 mg/kg daily (30 to 60 mg) for 4 to 8 weeks, then taper over 3 to 6 months.
• Steroid sparing options: azathioprine 2 mg/kg daily, mycophenolate 1 g twice daily, tamoxifen 10 to 20 mg twice daily (anti fibrotic), colchicine 0.6 mg twice daily, thalidomide 50 to 100 mg daily, cyclophosphamide, low dose naltrexone, rituximab 1 g on days 1 and 15 for IgG4 related disease.
• Nutritional support: enteral or parenteral nutrition for obstruction or malnutrition.
• Surgery for complete obstruction, ischaemia, perforation, or uncertain diagnosis: limited bowel resection; extensive mesenteric resection is avoided due to vascular compromise. Stoma or bypass procedures.
• Ureteral stenting for hydronephrosis.
• Follow up imaging every 6 to 12 months. Prognosis is generally favourable, with stabilisation in most.