Clinicopathological Features Of Extragastrointestinal Stromal Tumors

Objective:Extragastrointestinal stromal tumors(EGISTs) that arise out the gastrointestinal tract are rare.In recent years ,scientifec kniwledge on GIST has dramatically progressed,GIST as a distinct disease entity was identified. The aim of this study was to evaluate the clinicopathological, immunohistochemical features of intra-abdomen extra-gastrointestinal stromal tumors and to explore the reference parameters for aggressive behavior.Methods:Twelve cases of EGISTs were distinguished from the omentum ,mensentry or retroperitoneum which were previously diagnosed as leiomyoma leiomyoblastoma, or leiomyosarcoma etc by use of apanel of antibodies such as nestin ,CD117,CD34,SMA,S-100 in immumohistochemical SP method.The biologic behaviors were analyzed by the follow-up data and clinicopathological features.Result: Tumors occured in seven men and five women ,the age ranged from 22 to 73 years ( mean 55.2 years ). four cases arose from the mesentery ,three from omentum ,five from retroperitoneum.The most common symptom were abdomemal mass ,vague pain or abdomenal distention but gastrointestinal bleeding.The size of tumors ranged from 7 to 19 cm ( mean 12.5 cm) in diameter. Grossly ,they were of soft consistency of with hemorrhage,cystification or necrosis.Microscopically,the tumors were composed of spindle cells (8 cases) or epithelioid cells ( 2 cases) and mixed cells (2 cases).Arranged in interlacing fasicles,diffusing sheets, pallisading ,whirling, alveolar and pseudo-rosette shapes. Tumor cells often be long fusiform to short fusiform,or round.Tumor cells often had abundant cytoplasm with light to moderate eosinophilic or slight basophilic in staining.Tumors expressed CD117 (12/12) 100%,nestin (8/12) 66.7%,CD34 (7/12) 58.3% , S -100 one positive,SMA two positive.Evalue the cases by size ,mitotic index(5 /50HPF, 5-10 /50HPF, > 10 /50HPF), cell types. Size ( EGISTs/GISTs) is different (t=3.243, P=0.002) ,as MI (X~2 =3.889, P=0.049 ) . EGISTs group included four intermediate risk and eight high risk patients, five in metastasis with MI >...