Abstract
Calcification in gastrointestinal stromal tumor (GIST) is rare. Here we report a case of GIST of the stomach presenting with progressive calcification during imatinib treatment. A woman in her sixties was found to have a 5-cm diameter submucosal tumor of the stomach. It was diagnosed as gastrointestinal stromal tumor (GIST) of the stomach. Exploratory laparotomy revealed multiple nodules disseminated in the abdominal cavity. The histological diagnosis of GIST was made on the excised nodules, and the tumor was found to possess a missense point mutation at exon 11 of KIT gene. Oral treatment with imatinib at 400 mg/day was started. Two months after the treatment, the size of the tumor was reduced, and the density became darker. Fifteen months after initiation of the treatment, calcification was detected in the tumor. The calcified area progressively increased reaching 15.4 % of the section of the tumor 68 months after the initiation, though the tumor growth had been suppressed. Calcification appeared to be associated with the degeneration of the tumor caused by imatinib treatment. It is thus concluded that calcification may reflect the efficacy of imatinib treatment for GIST.
