Fatal abdominal sarcomatosis secondary to gastrointestinal stromal tumor with bland histology.

Fatal abdominal sarcomatosis is a rare complication secondary to gastrointestinal stromal tumor (GIST) arising from the small intestine. Here, we describe a 49-year-old man who presented with massive ascites and multiple mesenteric solid masses. Autopsy showed large necrotic mass (19 x 14 x 8.0 cm) surrounding the terminal ileum with multiple smaller nodules on the omentum and mesentery. Histological examination revealed highly cellular, predominantly bland, spindle cells with low mitotic activity. Gastrointestinal stromal tumor was confirmed by strong positive staining for c-KIT (CD 117). Our case is an example of fatal intra-abdominal sarcomatosis of GIST where the histological features were essentially bland.