Malignant Retroperitoneal Extra-Gastrointestinal Stromal Tumor: A Case Report

Context: Extragastrointestinal stromal tumors (EGIST) are extremely uncommon neoplasm. To the best of our knowledge, only one retroperitoneal EGIST case has been reported in Oncolgy, in 2005（PubMed search result).
Case Report: A 67-year old female patient presented with epigastric discomfort, dyspepsia, and anemia. Ultrasonographic examination of the abdomen showed the location of the tumor was between the tail of the pancreas and the spleen (retroperitoneal), it was variable in size of 12.3cm×7.2cm×14cm. Color Doppler Flow Imaging (CDFI) showed no flow signals with arterial-venous doppler spectrum in the masses．Contrast-enhanced computed tomography of the abdomen revealed a heterogeneously enhancing mass (8.23cm×14.2cm) and abundant blood supply of the tumor. The patient underwent gastroscopes-guided biopsy from the fundus of stomach for pathologic diagnosis and the result indicated chronic superficial gastritis. A complete gross excision was performed. Retroperitoneal tylectomy, left hepatic lobectomy, enterolysis, and liver biopsy were performed. Two weeks post operation, the patient was discharged without any postoperative problems. The final diagnosis of retroperitoneal EGIST was confirmed by histopathological examination and immunohistochemical findings (CD117 positivity).
Conclusion: We report a very rare case of retroperitoneal EGIST. Although the Ultrasonographic examination, computer tomography and endoscopy examination did not confirm the final diagnosis, they are complemented to each other in order to identify the exact location of the tumor. EGIST should be considered in the differential diagnosis of solid masses of abdomen on cytology and immunohistology.