Rare Occurrence of Gastric and Gallbladder Metastasis in Non-small Cell Lung Carcinoma (NSCLC): A Case Report

Abstract

Aim: Gastrointestinal metastasis from lung cancer (GMLC), particularly to the stomach and gallbladder, is a rare clinical entity, occurring in 0.5% to 14% of cases. These metastases often present with non-specific gastrointestinal symptoms or are incidentally detected, making early diagnosis a clinical challenge. This report highlights the diagnostic complexity and importance of histopathological confirmation in such rare cases. Presentation of Case: An 80-year-old female with Stage IVB non-small cell lung carcinoma (NSCLC) on Osimertinib therapy presented with new abdominal symptoms. PET-CT revealed a hypermetabolic lesion in the gastric lesser curvature and a distended gallbladder. Endoscopy identified a gastric ulcer, while elective cholecystectomy revealed chronic inflammation. Histopathology and immunohistochemistry (CK7, CK20, TTF-1, Napsin A) confirmed gastric and gallbladder metastases from primary lung adenocarcinoma. Discussion: Gastric and gallbladder metastases from NSCLC are exceedingly rare and may mimic benign lesions such as peptic ulcers or cholecystitis. While the stomach is an uncommon site of metastasis, the gallbladder is even more infrequently involved, typically identified through imaging or histologic analysis during unrelated surgery. Immunohistochemical staining, particularly TTF-1 and Napsin A, is pivotal in establishing pulmonary origin. Awareness of these unusual metastatic sites is critical for accurate staging and management. Treatment remains largely palliative, with systemic therapy being the cornerstone. This case reinforces the value of comprehensive diagnostic evaluation in advanced NSCLC with new gastrointestinal symptoms. Conclusion: Heightened clinical awareness and comprehensive diagnostic evaluation are crucial for patients with lung cancer presenting with new gastrointestinal symptoms. Enhanced understanding of the clinical presentation, diagnostic challenges, and management strategies GMLC is essential for improving patient outcomes and guiding future research in this area.