18F-FDG PET/CT Findings in a Patient With IgG4-Related Sclerosing Mesenteritis.

A large mass in the abdomen was revealed by ultrasonography on a 68-year-old woman presenting with abdominal pain and weight loss. To exclude the malignancy, an F-FDG PET/CT was performed, which showed a solitary soft tissue mass with heterogeneous F-FDG avidity at the root of small bowel mesentery. Because of the elevation of inflammatory markers and serum IgG4 level, IgG4-related sclerosing mesenteritis was suspected, which was proved by the subsequent biopsy. The mass gradually shrunk and ultimately disappeared in 6 months after a low-dose steroid therapy.