A Giant Gastrointestinal Stromal Tumor with Cystic Morphology.

An 89-year-old Japanese man was brought to our hospital with hematemesis. Contrast-enhanced computed tomography revealed a monolocular cystic tumor, measuring 11×10×10 cm between the stomach and the pancreas (Picture 1, arrows). Gastroscopy showed a large, soft bulge at the greater curvature in the upper gastric body, surmounted by a friable ulcer (Picture 2). The patient underwent partial gastrectomy 12 days after admission. Histologically, the resected specimen was found to be a cystic lesion with partial calcification (Picture 3). The cyst comprised serous fluid and blood. A pathological analysis revealed a spindle cell component (Picture 4) and immunohistochemical positivity for c-kit and CD34. The mitotic rate was ＞10/50 high-power fields. The tumor was diagnosed as a high-grade gastrointestinal stromal tumor (GIST) based on Fletcher's risk classification (1). Most GISTs are solid tumors, with cystic changes being uncommon (2). The cystic change in this case might have been caused by the rapid growth and necrosis of the tumor. GISTs presenting as monolocular cystic lesions, although rare, should be considered in the differential diagnosis of cystic lesions of the upper abdomen.

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The authors state that they have no Conflict of Interest (COI).