Fibroblastic reticular cell tumor of the spleen: report of a case and review of the entity.

Fibroblastic reticulum cells (FBRCs) are stromal support cells located in the parafollicular area and deep cortex of lymph nodes and in the extrafollicular areas of the spleen and tonsils. We report a case of malignant FBRC tumor of the spleen occurring in a 61-year-old woman. Two years after splenectomy, multiple hepatic lesions were found, which were resected. Histologically, the tumor showed similar morphological features in the spleen as in the liver metastases. There was a whorled pattern of oval and spindle cells in a collagenized background admixed with an inflammatory cell infiltrate composed of lymphocytes and plasma cells. The tumor cells were positive for common muscle actin, smooth muscle actin, and focally for CD68. In situ hybridization for Epstein Barr virus was negative. To the best of our knowledge, this is the first report of malignant FBRC tumor arising in the spleen. The differential diagnosis of splenic tumors with inflammatory pseudotumor-like features is discussed.