S3071 Humongous Refractory Gastrointestinal Stromal Tumor With an Unusual Mutation

Abstract

Introduction: Gastrointestinal stromal tumors (GIST) are rare mesenchymal neoplasms that arise from any part of the gastrointestinal tract. Its incidence varies between 7 and 8 percent per million inhabitants per year with a and median age of diagnosis of 63 years old. Extragastrointestinal stromal tumors make up less than 5 percent of cases, and most cases are secondary to advanced disease. Here we present a case of a catastrophic progression GIST with few or no previously documented mutation refractory to available therapies. Case Description/Methods: A 46-year-old man with a history of Omental GIST in remission after 5 years of treatment after imatinib attended the emergency room due to abdominal pain. Symptoms began suddenly with constipation, early satiety, and changes in stool size. Physical examination with a distended abdomen and positive liquid wave. laboratory analysis with 9.4 g / dL of hemoglobin. Abdominal CT reveals a large mesenteric mass measuring 15.6 x 10.2 x 24.6 cm in the lower abdomen extending into the pelvic region. Biopsy of the lesion reported a high-risk recurrent GIST with high Ki67 proliferation and a very high mitotic range. High-throughput and pathological sequences reported negative mutations in C-kit, CD117 and CD34, CDX-2, Betacatenin, LCA, CD3, CD20, Vimentin, and EXON 13,14 positive. Treatment was started with unanswered imatinib and then switched to sunitinib with disease progression and worsening disease burden. Treatment with regorafenib was started but, unfortunately, aggressive progression of the disease with a mass effect that affects multiple organs, so the patient did not tolerate the therapy. During the prolonged stay, the patient was complicated by spontaneous bacterial peritonitis, massive pulmonary embolism, and multi-organ failure, resulting in his death. Discussion: Our patient presented mutations in exon 13 and 14 rarely described in the literature that makes up less than 1% of GIST cases and does not have definitive treatment. It is presumed that the mutation in exon 13 responds to imatinib although in our patient it did not slow it down. progression of the disease. KIT-negative GISTs that progress during or after treatment with sunitinib and imatinib can be challenging for pathologists and clinicians. The implementation of next-generation gene sequences in clinical practice provides a major step forward in the implementation of target therapies and further studies. Tumor markers need to be developed for early detection, monitoring, and treatment.