S6485 GIST in the Mist: A Tumor Hidden Behind Common Symptoms

Introduction: Gastrointestinal stromal tumors (GISTs), the most common mesenchymal neoplasms of the GI tract, arise from interstitial cells of Cajal. They typically affect the stomach or small intestine, with peak incidence in adults aged 60–74. Clinical presentation varies by tumor size and location, from incidental findings to symptoms like GI bleeding, abdominal pain, or weight loss. Diagnosis relies on imaging, endoscopy, histopathology, and immunohistochemical markers such as CD117 (c-KIT), DOG1, and CD34. Timely recognition and consistent follow-up are critical to prevent complications and optimize outcomes. Case Description/Methods: A 46-year-old man with gastroesophageal reflux disease (GERD) and a known hiatal hernia presented with acute epigastric pain, hematemesis, melena, and syncope. On admission, he was anemic (hemoglobin 7.8 g/dL). Contrast-enhanced computed tomography (CT) showed a 4.8 cm enhancing mass along the stomach's greater curvature. Esophagogastroduodenoscopy identified a large (4–5 cm), ulcerated, non-actively bleeding gastric lesion. Biopsies confirmed spindle cell-type GIST, positive for CD117, DOG1, and CD34. He was stabilized and discharged on proton pump inhibitors, with plans for outpatient surgical follow-up; however, he was lost to follow-up. Six months later, he presented to another facility with worsening GI symptoms. Repeat imaging showed a persistent mass, and he underwent successful laparoscopic partial gastrectomy. Final pathology confirmed a 5.0 cm spindle cell GIST with low mitotic activity (4/5 mm²), negative margins, and classification as very low risk. Discussion: This case highlights diagnostic and management challenges in GIST, particularly in younger patients where neoplastic causes may be underappreciated. Initial symptoms may have been misattributed to pre-existing GERD and hiatal hernia, underscoring the need for a broad differential in persistent or atypical GI presentations. Loss to follow-up delayed definitive management and led to recurrence of symptoms. This case reinforces the need for clinician vigilance, patient education, and structured follow-up. Multidisciplinary coordination among gastroenterology, surgery, and pathology is vital to ensure timely diagnosis, treatment, and surveillance. Adjuvant imatinib may be considered based on risk stratification.