Gastrointestinal stromal tumor presenting as a large abdominal mass.

Objective: We report on a male patient operated on for a mesenchymal tumor of the digestive tract presenting a mega cyst-like abdominal mass.

Material And Methods: The size of the lesion was magnum, the mass presented as unilocular, the wall thickness was not uniform (0.1 to 1 cm) with hemorragic areas, the lesions were multiple measuring 3x2 cm and less, the mitotic index was borderline. The diagnosis was histologically defined as GIST borderline (low mitotic count and tumor size < 5 cm). The ultrasonography and TAC were unable to diagnostic information.

Conclusion: The GIST presents no specific signs and the most frequent symptoms are abdominal pain and abdominal mass, the CT scan and ultrasonography are sensitive in the evaluation of location, size, invasion of adjacent organs but not for diagnosis. Prognostic predictions are on the basis of mitotic index and tumor size (1). The precise cellular origin of GIST (2) has recently been proposed to be the interstitial cell of Cajal, an intestinal pacemaker cell. The gain-of function mutation of c-kit (receptor tyrosine kinase--KIT positive tumor) proto-oncogene has been detected in GIST and its role in molecular pathogenesis has been established. The treatment of unresectable and metastatic lesion is Imatinib mesylate, inhibitor of tyrosine-kinase activity (Gleevec, Novartis).