[Gastrointestinal stromal tumors (GIST). Clinical characteristics, diagnosis, and therapy in five cases].

Gastrointestinal stromal tumors (GIST) are rare causes of gastrointestinal bleeding. In most cases these tumors are localized in the stomach and small intestine, more rarely in the esophagus and colon.Pluripotent mesenchymal cells are the suspected origin of GIST. The pathogenesis is obviously initiated by gene mutations, leading to an overexpression and activation of tyrosine kinase proteins. This activation is followed by uncontrolled proliferation and loss of apoptosis. The immunohistochemical detection of the protein CD 117 (c-kit) is an important diagnostic tool. Activating c-kit mutations are observed in most cases of GIST. Grading of GIST remains a problem. Size and mitotic rate are the most powerful predictive factors associated with malignant behavior. The most common symptoms of GIST are pain and gastrointestinal bleeding. Endoscopy, sonography, scintigraphy or radiology -- enteroclysma, computed tomography (CT) and magnetic resonance imaging (MRI) -- are possible methods to detect a GIST. Surgical resection is the standard therapy of GIST. In cases of metastatic GIST, systemic therapy with imatinib, a tyrosine kinase inhibitor, frequently leads to partial remission and clinical improvement. Only few side effects are described. Five patients with GIST are reported. In all cases gastrointestinal bleeding was the main symptom. All tumors were surgically resected, and no signs of recurrence or metastasis have been observed in any of the patients so far (19-51 months postoperatively).