[A Case of Primary Splenic Inflammatory Myofibroblastic Tumor].

Inflammatory myofibroblastic tumor(IMT)is a rare neoplasm. IMTs are found in a number of locations throughout the body, but splenic involvement is uncommon. One case of splenic IMT is described. A 42-year-old woman presented with anterior chest pain and was found to have a splenic mass by computed tomography(CT). Fluorine-18-FDG-PET showed no FDG accumulation in the spleen. Magnetic resonance imaging(MRI)at 6 months follow-up showed an increase in the size of the tumor. We performed splenectomy for a suspected malignant tumor. The surgical specimen was a gray-white mass in the spleen. The mass was histopathologically diagnosed as primary splenic IMT because it consisted of desmin- and SMA-positive spindle-shaped cells with various inflammatory cells. In Japan, only 6 cases(including this case)of primary splenic IMT have been reported. Surgery is the only curative approach, but recurrences occur in around 5% of cases of pulmonary IMT, and around 25% of cases of extrapulmonary IMT. This patient needs to be carefully followed up.