Primary Extra-gastrointestinal Stromal Tumor of Retroperitoneum

BACKGROUND: Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract. More rarely neoplasms with histology and immunohistochemistry similar to GISTs may occur outside the gastrointestinal tract ( omentum, mesentery and retroperitoneum) and are so-called Extra-gastrointestinal Stromal Tumors (EGISTs). EGISTs arising in the retroperitoneum are extremely rare: to date, only 58 cases have been reported in the literature. CASE REPORT: We herein report a case of a primary EGIST of the retroperitoneum surgically treated. The pre-operative radiological evaluation showed a retroperitoneal mass, placed in left paravertebral region. RESULTS: Morphological and immunohistochemical features led to a diagnosis of extra-gastrointestinal stromal tumor (intermediate-low risk form). CONCLUSIONS: As a result of the rarity of reports of primary EGISTs of retroperitoneum we need to analyze the data of reported cases in order to gain a better understanding about the pathogenesis, prognosis and optimal treatment of this disease.