Sclerosing Mesenteritis Complicated With Mesenteric Lymphoma Responsive to Ustekinumab.

A 45-year-old man with a 10-year history of biopsy-proven, steroid-dependent sclerosing mesenteritis failed/was intolerant to tamoxifen, azathioprine, colchicine, cyclophosphamide, and methotrexate. He developed osteoporosis, diabetes, and bilateral cataracts. He responded to infliximab but was diagnosed with mesenteric large B-cell lymphoma 6 months after treatment initiation. He achieved remission from lymphoma after chemotherapy, but the sclerosing mesenteritis remained poorly controlled. He was treated with ustekinumab (520 mg intravenously followed by 90 mg subcutaneously every 8 weeks), leading to complete steroid-free remission. He remains symptom and cancer-free 24 months after starting ustekinumab.