[Gastrointestinal stromal duodenal tumors: diagnostic mistakes and modern approaches to treatment].

Gastrointestinal stromal duodenal tumors are rare diseases of small intestine. Duodenal GISTs may be giant; these neoplasms can also simulate malignancies of other organs. These features result diagnostic and treatment mistakes. Neoadjuvant therapy with imatinib results tumor shrinkage and ensures organ-sparing surgery. We report duodenal GISTs in patients with primary diagnosis «retroperitoneal tumor», «pancreatic cyst» and «retroperitoneal abscess», who were treated at the Blokhin National Cancer Research Centre in 2019-2020.