A Case of an Inflammatory Pseudotumor-Like Follicular Dendritic Cell Tumor of the Spleen Unrelated to Epstein-Barr Virus

A splenic tumor was found in a 39-year-old man through abdominal ultrasonography on April 2008. He then consulted the Department of Gastroenterology at Ojiya General Hospital. Dynamic computed tomography (CT) showed an 8.0-cm hypovascular lesion of the spleen in early phase. But the lesion enhanced to the same degree as the surrounding splenic parenchyma in delayed phase. Since the CT radiologic examination of the tumor was equivocal, and inadequate to rule out malignancy, a splenectomy was performed for diagnostic treatment. Microscopically, the lesion was an admixture of spindle cells and inflammatory cells, chiefly lymphocytes, plasma cells and histiocytes. These tumor cells were immunoreactive to CD35, fascin and clusterin. We made a diagnosis of follicular dendritic cell tumor of the spleen. The test for Epstein-Barr virus, (EBV)-encoded RNA1 (EBER1), was negative. The patient has experienced no recurrence in the 31 months after surgery.