Mesenteric panniculitis presenting as fever of unknown origin.

A 40-yr-old man was admitted for fever of unknown origin. Mesenteric panniculitis was suspected as a result of ultrasonography, computed tomography, and nuclear magnetic resonance findings, and that diagnosis was confirmed by laparoscopy with retroperitoneal mass biopsy. Mesenteric panniculitis is a rare disease characterized by an inflammatory process of the mesenteric adipose tissue. Abdominal pain, weight loss, and abdominal mass are the most frequent symptoms. High fever and leukocytosis are uncommon. To the best of our knowledge, only two reports of mesenteric panniculitis presenting as fever of unknown origin have been described previously, with no cases published in the English literature. In the case reported, steroid therapy was started with initial improvement. Despite the temporary addition of azathioprine and the maintenance of the prednisone treatment, no further improvement has been achieved. Two years and 5 months after admission, the patient presents intermittent episodes of fever and muscle pain.