How is sclerosing mesenteritis diagnosed and managed in a middle‑aged to older adult presenting with vague abdominal pain and possible weight loss?

Sclerosing Mesenteritis: Diagnosis and Management

Diagnostic Approach

CT scan with IV contrast is the definitive diagnostic imaging modality for sclerosing mesenteritis, demonstrating characteristic mesenteric fat stranding, soft tissue mass, and the "fat ring sign" with near 100% sensitivity. 1, 2

Initial Clinical Presentation

• Abdominal pain occurs in 70% of patients, typically chronic and vague in the mid-epigastrium or periumbilical region 1, 3
• Weight loss is present in 23% of cases and should raise concern for mass effect or associated malignancy 1
• Diarrhea affects 25% of patients due to bowel involvement or lymphatic obstruction 1
• Median age at presentation is 65 years with 70% male predominance 1

Imaging Strategy

CT abdomen/pelvis with IV contrast should be performed first in all suspected cases, as it provides both diagnosis and assessment of complications including bowel obstruction, vascular compromise, and associated malignancies 2, 3. The characteristic findings include:

• Mesenteric fat stranding with soft tissue density mass
• "Fat ring sign" (preserved fat around mesenteric vessels)
• Calcifications and fibrotic changes in chronic cases 2, 3

MRI enterography can be used as an alternative when IV contrast is contraindicated or to better characterize the extent of mesenteric involvement 3.

Laboratory Evaluation

• Complete blood count to assess for anemia from chronic disease or occult bleeding 1
• C-reactive protein and ESR to evaluate inflammatory activity, though these are nonspecific 1
• Serum albumin to assess nutritional status, particularly in patients with weight loss 1

Tissue Diagnosis Considerations

Biopsy is not routinely required when imaging findings are characteristic, but should be obtained when:

• Malignancy cannot be excluded radiographically
• Atypical features are present
• Treatment decisions depend on histologic confirmation 2, 3

Histology shows fat necrosis, chronic inflammation, and fibrosis of the mesentery 1, 2. Surgical biopsy may be necessary when percutaneous sampling is unsafe due to vascular involvement 3.

Management Algorithm

Asymptomatic or Incidentally Discovered Disease

Observation with serial imaging every 6-12 months is appropriate, as the natural history is generally benign and 52% of patients require no treatment 1, 2.

Symptomatic Disease Requiring Medical Therapy

Tamoxifen 20 mg twice daily plus prednisone 40 mg daily (tapered over 6-8 weeks) is first-line therapy for symptomatic patients, with 60% response rate in the largest case series 1, 2.

The rationale for this combination:

• Tamoxifen inhibits fibroblast proliferation and has anti-inflammatory properties 1, 4
• Corticosteroids address the inflammatory component 1, 2
• Tamoxifen monotherapy can achieve complete resolution in select cases, particularly when inflammation is minimal 4

Non-tamoxifen regimens (azathioprine, colchicine, cyclophosphamide) showed only 8% response rates and should be reserved for tamoxifen failures 1.

Surgical Intervention

Surgery is indicated only for:

• Persistent bowel obstruction despite conservative management
• Inability to exclude malignancy
• Vascular compromise causing mesenteric ischemia 1, 2, 3

Complete resection is often not feasible due to intimate involvement with mesenteric vasculature, and bypass procedures may be necessary 3, 5. Only 10% of patients respond to surgery alone, while 20% improve with post-operative medical therapy 1.

Critical Management Considerations

Associated Conditions to Screen For

Retroperitoneal fibrosis can develop in patients with sclerosing mesenteritis and should be suspected if urinary symptoms or renal dysfunction emerge 5. Obtain:

• Renal function tests at baseline and follow-up
• CT or MRI to evaluate retroperitoneum if symptoms develop 5

Malignancy is associated with sclerosing mesenteritis in up to 20% of cases, requiring:

• Age-appropriate cancer screening
• Investigation of any new symptoms suggesting malignancy 1, 2

Treatment Duration and Monitoring

• Continue tamoxifen for at least 6-12 months after symptom resolution 1, 2
• Repeat CT imaging at 3-6 months to assess radiographic response 2
• Long-term follow-up is essential as relapse can occur after treatment discontinuation 1

Mortality and Prognosis

Mortality directly attributable to sclerosing mesenteritis or its treatment occurs in 17% of cases, typically from:

• Bowel obstruction with perforation
• Mesenteric ischemia
• Complications of immunosuppressive therapy 1

The clinical course is generally benign but can be prolonged and debilitating, requiring years of treatment in some patients 1, 2.

Common Pitfalls to Avoid

• Do not delay imaging with CT contrast in favor of less sensitive modalities, as early diagnosis prevents complications 2, 3
• Do not pursue surgical resection as first-line therapy unless obstruction or malignancy is present, as medical therapy is more effective 1, 2
• Do not use corticosteroids alone without tamoxifen, as combination therapy has superior response rates 1
• Do not assume the diagnosis is benign without excluding associated malignancy through appropriate screening 1, 2