OBJECTIVETo investigate the clinicopathological characteristics and prognostic factors in patients with intra-abdomen extragastrointestinal stromal tumors (EGISTs).

METHODSThe data of 47 patients of mesenchymal neoplasms that arose from the abdominal cavity and retroperitoneum, collected from July 1987 to June 2003 in our hospital with complete clinical and pathological data, were investigated retrospectively. EGISTs were diagnosed by reviewing the tumor slides stained with hematoxylin and eosin (H&E). Immunohistochemistry staining were performed on CD117, CD34, smooth muscle actin, Desmin and S-100 proteins. The relations of various clinicopathologic characteristics and outcomes were examined.

RESULTSAmong the 47 cases, 30 tumors were confirmed to be EGISTs. Twelve cases arose from the mesentery, six from small omentum, eight from retroperitoneum and four from the abdominal cavity. The size of tumors ranged from 4 to 30 cm (median 12.5 cm) in diameter and the tumor cell components mainly included spindle cells (23 cases), epithelioid cells (4 cases), and mixed cells (3 cases). The follow-up rate was 90% and the median follow up time was 44 months. The patient survival rates at 1, 5 and 10 years were 79.7%, 59.5% and 45.4% respectively. Univariate analysis showed that tumor size >10 cm, tumor necrosis, mitoses > or =5/50HPF, obvious nuclear atypia, moderate and poor differentiated tumor cells were predictors of poor prognosis.

CONCLUSIONSEGISTs have specific clinical behaviors. The parameters used for predicting GISTs prognosis are not completely applicable for EGISTs. Tumor necrosis, obvious nuclear atypia and mitoses > or =5/50HPF help to predict aggressive behaviors in EGISTs.