[Gastric stromal tumor with myxoid degeneration. Report of a case and review of the literature]. / Tumor estromal gástrico con degeneración mixoide. Reporte de un caso y revisión de la literatura.

BACKGROUND: Gastrointestinal stromal tumors (GIST's) represent a heterogeneous group of neoplasms that have as their common histologic denominator an immature proliferation of epithelioid or spindle cells. Although originally believed to represent atypical variants of leiomyoma or leiomyosarcoma, recent studies have demonstrated that only a subset of such tumors actually display well developed immunohistochemical, ultrastructural features of smooth muscle differentiation. Most gastrointestinal mesenchymal tumors are of uncertain histogenesis. Current studies have shown a striking morphological and immunophenotypic similarities of these tumors with the interstitial cells of Cajal. And that they may originate from stem cells that differentiate toward a pacemaker cell phenotype. Most GIST's have a co-expression of Kit (CD117) or CD34, which is also express in interstitial cells of Cajal. OBJECTIVE: This review will attempt to summarize the current knowledge and understanding of these lesions based on review of the literature, with an analysis of the criteria for distinguishing between benign and malignant tumors. METHOD: We report a Gastrointestinal Stromal Tumor of the stomach with prominent cystic degeneration. The patient had diarrhea, abdominal pain and was found to have abdominal mass. X-ray and computed axial tomography examination showed a lesion that seems to be a pancreatic cystic lesion. At laparotomy a large intramural tumor located in the stomach was found. Histologically, the lesion was composed of epithelioid and spindle cells embedded in an abundant myxoid stroma. Tumor cells showed positive staining for vimentin and CD34 positive. We conclude that the diagnosis of gastrointestinal stromal tumor whit prominent cystic degeneration can be made in this case.