The gastrointestinal stromal tumor with extragastrointestinal location are very infrequent. We often diagnose them when they show a big size. Their bening or malignant nature is difficult to fix. The best histological parameters to evaluate their prognosis are a high cellularity, the tumor-like necrosis presence and having more than two mitosis per fifty high-power fields. We introduce an asyntomatic patient's case by a routine echographical control for chronic hepatitis by C virus, that has been diagnosed of a mesentery tumor. The patient has been treated surgically. The inmunohistological study of the tumor had confirmed a stromal gastrointestinal tumor. The showed case's analysis and the considered bibliography suggest some clinical discoveries characteristic of this entity. The histogenesis of these neoplasias are examined and made up to date and the usefulness of the new medication to control check the tumor-like progress is emphasized.