Dramatic disappearance of hyperglycemia and abnormal neurologic symptoms after resection of duodenal gastrointestinal stromal tumor.

Gastrointestinal stromal tumor (GIST) is a common mesenchymal neoplasm of the gastrointestinal (GI) tract. Paraneoplastic syndromes of GISTs are rare; in particular, GIST-induced hyperglycemia has not been reported. A 67-year-old woman presented with recurrent alteration of consciousness and uncontrolled hyperglycemia. Computed tomography scans showed a huge hypervascular mass, located medial to the superior mesenteric vessels. Endoscopic ultrasonography (EUS) with fine-needle aspiration (FNA) showed spindle cell tumors, diagnosed as borderline resectable duodenal GIST. There was partial response after 6 months of Imatinib treatment. En-bloc resection was performed via the laparotomy. The histology confirmed a high-risk GIST at the third part of the duodenum. The abnormal symptoms then dramatically disappeared. She has remained recurrence free for 22 months. Uncontrolled hyperglycemia and abnormal neurological conditions are rare in GIST; however, a large hypervascular GIST could cause paraneoplastic syndromes or consume the products from an adjacent structure, requiring complete tumor resection. This case adds the knowledge of an extremely rare presentation of GIST and, moreover, extremely rare cause of uncontrolled hyperglycemia.