In a 71-year-old man with CT abdomen and pelvis showing new central mesenteric and retroperitoneal lymphadenopathy with surrounding mesenteric inflammation suggestive of sclerosing mesenteritis versus lymphoma, what is the most appropriate next step in management?

Management of Mesenteric Lymphadenopathy with Surrounding Inflammation

In this 71-year-old man with CT findings suggestive of sclerosing mesenteritis versus lymphoma, tissue biopsy is mandatory to definitively distinguish between these entities, as lymphoma requires immediate oncologic treatment while sclerosing mesenteritis may not require any intervention if asymptomatic. 1, 2

Why Biopsy is Essential

The CT findings described—central mesenteric and retroperitoneal lymphadenopathy with surrounding mesenteric inflammation—create diagnostic ambiguity that cannot be resolved by imaging alone:

• Sclerosing mesenteritis and lymphoma have overlapping CT appearances. Both can present with mesenteric fat stranding, lymphadenopathy, and soft tissue masses. 2, 3
• The distinction has profound treatment implications. Lymphoma requires chemotherapy or immunotherapy with significant impact on mortality, while asymptomatic sclerosing mesenteritis requires no treatment at all. 1, 4
• Sclerosing mesenteritis has a documented association with lymphoma, melanoma, and other malignancies, making it critical to exclude concurrent neoplastic disease even if sclerosing mesenteritis is present. 5

Biopsy Approach

Obtain tissue via CT-guided core needle biopsy of the most accessible enlarged lymph node or mesenteric mass:

• Target retroperitoneal or mesenteric lymph nodes rather than the inflamed mesenteric fat itself, as lymph node architecture is more diagnostic. 3
• Core needle biopsy is preferred over fine needle aspiration to allow assessment of tissue architecture, immunohistochemistry, and flow cytometry necessary for lymphoma diagnosis. 4
• If percutaneous biopsy is technically difficult or yields non-diagnostic tissue, laparoscopic biopsy should be pursued. 2, 6

Concurrent Diagnostic Workup While Awaiting Biopsy

Complete staging evaluation for potential lymphoma:

• PET-CT scan to assess metabolic activity and extent of disease. Lymphoma typically shows FDG-avid lymphadenopathy, while sclerosing mesenteritis shows variable uptake. 4
• Complete blood count with differential to evaluate for circulating lymphoma cells or cytopenias suggesting bone marrow involvement. 4
• Serum LDH and beta-2 microglobulin as prognostic markers if lymphoma is confirmed. 4
• Peripheral blood flow cytometry if there is lymphocytosis or concern for leukemic phase of lymphoma. 4

Assess for associated conditions with sclerosing mesenteritis:

• Review surgical history, as prior abdominal surgery increases risk of sclerosing mesenteritis. 1
• Screen for autoimmune diseases (retroperitoneal fibrosis, sclerosing cholangitis, Riedel thyroiditis) that associate with sclerosing mesenteritis. 2

Clinical Assessment of Symptoms

Determine if the patient is symptomatic, as this guides urgency and treatment:

• Symptomatic findings requiring urgent intervention: Abdominal pain, weight loss, bowel obstruction, palpable abdominal mass, or signs of mesenteric vessel thrombosis. 1
• Asymptomatic patients with sclerosing mesenteritis require no treatment, making the distinction from lymphoma even more critical. 1
• Many patients with sclerosing mesenteritis are asymptomatic and discovered incidentally, but lymphoma at this stage of lymphadenopathy typically requires treatment regardless of symptoms. 1, 4

Common Diagnostic Pitfalls to Avoid

• Do not assume sclerosing mesenteritis based on imaging alone. Mesenteric carcinomatosis, carcinoid tumor, desmoid tumor, and lymphoma all can mimic sclerosing mesenteritis on CT. 2, 3
• Do not delay biopsy in favor of empiric steroid trial. This can obscure lymphoma diagnosis and delay curative treatment. 1, 4
• Do not attribute symptoms to "mesenteric lymphadenopathy" without tissue diagnosis. The differential diagnosis includes life-threatening conditions requiring immediate treatment. 3

Post-Biopsy Management Pathways

If biopsy confirms lymphoma (specifically marginal zone lymphoma given mesenteric location):

• Immediate hematology-oncology referral for staging completion and treatment planning. 4
• Complete staging with bone marrow biopsy if not already performed. 4
• Treatment typically involves chemotherapy or immunotherapy depending on histologic subtype and stage. 4

If biopsy confirms sclerosing mesenteritis:

• Asymptomatic patients: Observation only with no treatment required. 1
• Symptomatic patients: First-line therapy is tamoxifen 10 mg twice daily plus prednisone 40 mg daily, though this is based on case series rather than randomized trials. 1
• Refractory bowel obstruction: Surgical intervention may be necessary but is often limited by vascular involvement. 2
• Follow-up CT imaging to monitor for progression or complications (bowel obstruction, vascular thrombosis, chylous ascites). 2