Heterogenous Intertumoral KIT Mutations in Long-term Stage 4 Gastrointestinal Stromal Tumor Survivor

Abstract Gastrointestinal stromal tumors (GISTs) are mesenchymal neoplasms of the gastrointestinal tract, with a prevalence of 5% out of all sarcomas. We herein report the case of a 54-year-old man with metastatic GIST who initially presented to the emergency department with severe “anemia” CT examination revealed a 22 cm mass adherent to his small bowel and associated pelvic ascites and metastases. Surgical excision of the abdominal wall mass and partial omentectomy demonstrated extensive necrosis and a tumor mitotic rate of 17 per 5 mm2 . Molecular profiling of the primary mass showed a KIT exon 9 mutation. Despite eight years of sunitinib treatment, followup PET-CT evaluation showed three enlarging omental/peritoneal masses. Surgical excision and molecular profiling of each mass, opposed to the standard practice of profiling only one, demonstrated different KIT exon mutations between each mass, each with resistances to different tyrosine kinase inhibitor treatments. Article Highlights Metastatic gastrointestinal stromal tumor can attain novel mutations Performance of therapies may decline in the setting of novel KITmutations Molecular profiling of multiple metastatic nodules may aid in treating specific mutationsInternational Journal of Clinical and Medical Cases (ISSN:2517-7346