[Stromal tumors of the small intestine (GIST). Prognostic differences based on clinical, morphological and immunophenotypic features].

Gastro Intestinal Stromal Tumors (GIST) are rare malignant non-epithelial tumors arising from gastro-intestinal tract. They represent the 0.2% of all malignancy of this site. Three cases, treated in our Department, are an example of the anatomo-clinical features of these tumors. In two cases the clinical features on admission were similar to those of acute abdominal pain; in the third one a palpable mass rapidly growing was observed. All three patients had surgical treatment but survival were quite different. The size of tumor mass in the first two cases was 5 cm; one patient was alive after ten years without relapse, the second one died five years after with liver metastasis. The third one, with a mass larger more than ten centimeters, developed 8 months after surgical resection a diffuse local relapse of the disease. The microscopic pattern and the lack of epithelial markers allowed to classify them as GIST. All cases were tested with S100 protein, smooth muscle actine, and CD-34 antigen. Two cases had both smooth muscle and nervous markers, the third resembled a malignant schwannoma. Prognosis was correlated with the size of tumor at the time of surgery and immunophenotype pattern. The tumors with high expression of nervous antigens had a worse prognosis.