Malignant gastrointestinal stromal tumor originating in the lesser omentum, complicated by rapidly progressive glomerulonephritis and gastric carcinoma.

A 69-year-old man was admitted with a large elastic mass in the upper abdomen. Computed tomography revealed a massive tumor in contact with the liver and gastrointestinal endoscopy revealed a gastric adenocarcinoma. He developed acute renal failure with massive proteinuria and died with a marked enlargement of the tumor. Autopsy revealed a tumor located in the lesser omentum. The tumor was considered to be a Gastrointestinal Stromal Tumor (GIST) because it was positive for c-kit. In addition, crescent formations and immune complexes in glomeruli were observed. We report the first case of GIST complicated by rapidly progressive glomerulonephritis and gastric carcinoma.