Gastrointestinal Stromal Tumor in a Patient with Neurofibromatosis Type 1 that Was Successfully Treated with Regorafenib

An unconscious 55-year-old man with a history of neurofibromatosis type 1 (NF1) was transported to the emergency department and was diagnosed with acute renal failure owing to a large bladder tumor. A submucosal tumor was also identified in the duodenum. The patient was diagnosed with a primary gastrointestinal stromal tumor (GIST) of the bladder and duodenum. After six cycles of regorafenib therapy, 18F-fluorodeoxyglucose accumulation in the duodenal GIST on positron emission tomography-computed tomography (PET-CT) showed a partial metabolic response. Currently, no standard drug therapy for unresectable or relapsed NF1-associated GIST has been established. Regorafenib may thus be considered as and appropriate initial therapy.