[A case of sclerosing mesenteritis diagnosed on the basis of biopsy findings obtained during laparotomy and successfully treated with steroids].

A 53-year-old female who complained of constipation and abdominal fullness was referred to our hospital. A tender low abdominal mass was palpable. Imaging (abdominal ultrasonography, CT, and MRI) revealed that the tumor had spread to the mesosigmoid and the superior mesentery. The tumor was very difficult to diagnose on the basis of imaging alone. Therefore, we obtained a biopsy at the time of laparotomy for definitive diagnosis. The biopsy showed extensive fibrosis and lymphocyte, plasma cell, and eosinophil infiltration in the associated adipose tissue. Sclerosing mesenteritis was diagnosed. The patient's symptoms improved immediately after initiating steroid therapy. Pathological examination and empirical steroid therapy are useful for the diagnosis and medical treatment of sclerosing mesenteritis, respectively.