S6275 When Standard Diagnostics Fail: A Case of Gastric Linitis Plastica With Negative Work-Up

Introduction: Gastric linitis plastica (GLP) is described as thickening of the gastric wall without notable ulceration. GLP can be particularly difficult to diagnose via endoscopy due to the submucosal infiltration of the malignancy. Here we present a case of GLP in a patient with a negative computed tomography (CT), esophagogastroduodenoscopy (EGD) biopsy, and indeterminate upper GI series. Case Description/Methods: A 63-year-old man presented with a 3-month history of epigastric pain with nocturnal awakening, dysphagia to solids, loss of appetite, acid reflux, and intermittent changes in stool consistency. His past medical history was significant for Parkinson’s disease. A CT scan of the abdomen and pelvis revealed only sigmoid diverticulosis and an inguinal hernia. EGD identified a partially obstructing, infiltrative 44 mm gastric mass in the body of the stomach, with stigmata of recent bleeding. Initial biopsies showed reactive changes without malignancy, and initial laboratory tests, including carcinoembryonic antigen, were unremarkable. Due to persistent symptoms, an upper GI series with a barium swallow was performed but yielded negative results. However, endoscopic ultrasound (EUS) revealed gastric wall thickening up to 22 mm, involving the luminal interface, superficial mucosa, and deep mucosa. Fine-needle aspiration (FNA) confirmed poorly differentiated adenocarcinoma with signet ring features. Follow-up pathology was negative for HER2, with CD117 and DOG1 also negative, ruling out gastrointestinal stromal tumor (GIST). PD-L1 testing was positive. During surgical exploration, multiple peritoneal implants were discovered. Given the extent of the disease, the patient elected to initiate immunotherapy, which resulted in a poor response. Eventually, he was admitted to hospice care. Discussion: Diagnosing gastric linitis plastica (GLP) can be particularly challenging, as the primary lesion often lies deep within the gastric wall. Up to 30% of initial cold forceps biopsies may yield false-negative results in GLP cases. In such situations, endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) is crucial for obtaining tissue samples from the submucosal and deeper layers. This case underscores the diagnostic difficulty of GLP, given its nonspecific symptoms—such as dysphagia, weight loss, and epigastric pain—and the often inconclusive findings on imaging, blood work, and initial biopsies. While imaging studies are valuable tools in the diagnostic process, they should not replace careful clinical judgment.