Synchronous gastric cardia and antrum signet ring cell carcinomas: A rare case report highlighting diagnostic challenges and multidisciplinary management

Importance of clinical vigilance: Although this patient had no family history of gastric cancer, her nonspecific gastrointestinal symptoms ultimately led to the diagnosis of dual primary SRCC. This highlights the need for high suspicion of malignancy in elderly patients presenting with nonspecific symptoms.Diagnostic value of multidisciplinary collaboration: The integration of endoscopic, pathological, imaging (computed tomography/magnetic resonance imaging), and immunohistochemical findings enabled accurate diagnosis of this rare case of dual primary gastric malignancy and identification of HER2 expression heterogeneity. The heterogeneity in HER2 expression (1+ vs 3+) demonstrates potential molecular differences between lesions in the same patient, emphasizing the necessity for comprehensive biopsy sampling.