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

rationaleGastric cancer is one of the most common malignant tumors in China. Gastric signet ring cell carcinoma (SRCC) belongs to highly malignant undifferentiated gastric cancer, originating from the epithelial cells of the gastric mucosa. Research has shown that the incidence of gastric cancer is gradually decreasing, but the incidence of gastric SRCC is gradually increasing. We report an extremely rare case of dual primary SRCC involving the gastric cardia and antrum. This case highlights the diagnostic challenges of synchronous SRCC, where a high level of suspicion, comprehensive endoscopic evaluation, and multidisciplinary management are crucial for achieving optimal treatment outcomes. PATIENT CONCERNS: The 69-year-old female patient presented with poor appetite and significant weight loss, prompting her hospitalization. Following diagnostic evaluations, she was diagnosed with dual primary SRCC involving both the gastric cardia and antrum. Postsurgery, she experienced severe complications, including malnutrition, postoperative infections, and intestinal obstruction, significantly impairing her quality of life. Currently, she remains under regular chemotherapy (Tegio) and trastuzumab-targeted therapy. DIAGNOSES: The patient was finally diagnosed with double primary SRCC of the cardia and antrum of the stomach through gastroscopy and pathological tissue biopsy.

interventionsLaparoscopic radical total gastrectomy (October 28, 2024)Adjuvant therapy: Tegio chemotherapy + trastuzumab (human epidermal growth factor receptor 2 [HER2] targeted). OUTCOMES: Complications such as malnutrition, postoperative infection, intestinal obstruction, as well as complications related to chemotherapy and targeted therapy, which had a serious impact on the quality of life. LESSONS: 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.