[A Case of a Large Gastric Gastrointestinal Stromal Tumor with a PDGFRA Exon 18 Mutation].

A 49-year-old man visited our hospital with a chief complaint of abdominal pain that began 1 day before his visit.An approximately 30 cm tumor that was extensively in contact with the gastric wall in the abdominal cavity was detected on computed tomography(CT).An elevated lesion covered with normal mucosa on the posterior wall of the greater curvature was detected on upper endoscopy.He was diagnosed with a submucosal tumor of the stomach, and he underwent surgery. Surgical findings revealed an elastic soft tumor with a maximal dimension of 38 cm that projected from the posterior wall of the stomach beyond the gastric wall.No invasion and metastasis to other organs were detected.Partial gastrectomy was performed.On histopathological examination, proliferation of atypical round and spindle cells was found, and immunostaining was negative for KIT but positive for CD34.In the gene search, an Asp842Val mutation was detected in exon 18 of the PDGFRA gene.Currently, the patient has survived for 7 months after surgery without recurrence.