1999 Volume 38 Issue 4 Pages 328-331
Background: Traditionally, most mesenchymal tumors of the gastrointestinal tract were diagnosed as smooth muscle tumors. Recently, however, immunohistochemical studies have revealed that gastrointestinal mesenchymal tumors are divided into two types, the first group consisting of tumors with smooth muscle or nerve sheath characteristics, and the second being tumors composed of cells of an undetermined lineage. The latter is now referred to as a gastrointestinal stromal tumor (GIST). We report a case of GIST arising in the stomach.Case: The patient was a 60-year-old woman. Abdominal computed tomography and magnetic resonance imaging showed a huge tumor filling the upper abdomen. Specimens obtained by aspiration biopsy cytology (ABC) revealed a large number of isolated or clustered spindle-shaped cells often with elongated blunt-ended nuclei and with scanty cytoplasm. Some nuclei showed snapped indentation. Macroscopically, the tumor measured 18×15×10 cm and showed wide areas of necrosis and hemorrhage. Histologically, the tumor appeared to have arisen from the muscularis propria of the stomach, and was composed of interlacing fascicles of spindle-shaped cells with eosinophilic cytoplasm. Mitotic figures were frequent and some of were atypical. Immunohistochemically, the tumor cells were positive for CD 34 and vimentin, and negative for myogenic markers (desmin, alpha-SMA and HHF 35) and for S-100 protein.Conclusion: It is possible on occasion to diagnose mesenchymal tumors of the gastrointestinal tract as GIST by the ABC method.
