Metastatic Inflammatory Myofibroblastic Tumor of the Spleen: A Case Report and Review of the Literature.

Introduction. Inflammatory myofibroblastic tumors (IMT) of the spleen are rare neoplasms and only little is known about the origin and behavior of these tumors. Here we report the case of a 37-year-old woman with an atypical spindle cell neoplasm showing features strongly suggesting an IMT of the spleen with hepatic metastasis. Methods. A 37-year-old patient had been complaining about pain in the left upper abdomen for the last two months. A CT scan revealed a tumor mass in her spleen and liver. After complete staging, a splenectomy and atypical liver resection of segments VII and VIII were performed. Literature was screened for similar cases and existing further literature. Results. A R0 resection was achieved. Histological analysis showed a multinodular infiltration of the spleen by an atypical mesenchymal neoplasia. Immunohistochemically there was an expression of histiocytic markers (CD4, CD68) as well as smooth muscle cell markers (SMA, H-Caldesmon) in the tumor cells. A diagnosis of an atypical spindle cell neoplasm showing features most suggestive of an IMT was rendered. Conclusion. Synchronous hepatic metastasis of an IMT of the spleen is a rarity. Therefore no experience in the treatment of these tumors exists. Fibroblastic reticular cell tumor is a differential diagnosis, but differentiation of these two entities is difficult.