Case Report: An uncommon germline variant of familial GISTs: broadening the landscape of inherited GIST syndromes

Familial Gastrointestinal Stromal tumors (GIST) are rare neoplasms but GIST tumors are some of the most common soft tissue sarcoma subtypes. The incidence is between 10 to 15 cases per million worldwide and approximately 500 cases in the USA [1]. GIST is often diagnosed based on clinical presentation, the tumor's anatomic location and immunohistochemistry (IHC) pattern [1]. Patients with familial GIST develop GIST tumors that are numerous, smaller in size, and occur in the background of intestinal cells of Cajal hyperplasia [2]. The first family with features of inherited GIST was reported in the 1990s which was the first time Exon 11 KIT variant was reported [3]. We present two cases of family members affected with multifocal GIST tumors who underwent germline genetic analysis and were found to have germline pathogenic variants in Exon 11 of the KIT gene [c.1735_1737del (p.Asp579del)]. Both patients were treated with Imatinib with good response.