Abstract
A 71-year-old woman was referred to our hospital for further examination and treatment after a tumor, approximately 5 cm in diameter, was detected in the right upper quadrant on abdominal ultrasound as part of a medical check-up. Gastrointestinal stromal tumor (GIST) of the duodenum with extramural spread was suspected based on MRI, CT, and other tests, and surgery was performed. A solid mass, 5 cm in size, was observed on the ventral side of the head of the pancreas, and it was detached from the duodenum. Because the mass adhered to the pancreas, the tumor was resected by excising part of the head of the pancreas. Based on the histopathological findings (CD34-positive, c-kit-negative, etc.), the mass was diagnosed as a solitary fibrous tumor (SFT). The patient's postoperative course was favorable. SFT is known to occur in the pleura and soft tissue, and it rarely occurs in the abdominal cavity. It is a lesion that is difficult to evaluate for malignancy. In addition, it has been reported that local recurrence is very likely if the tumor is not completely resected in the present patient, although malignancy may be unlikely based on tumor size and the absence of high degrees of atypia and pleomorphism, further careful follow-up is considered necessary.
