Hereditary diffuse gastric cancer is a rare epithelial tumor of the stomach, characterized by the development of diffuse (signet ring cell) gastric cancer at a young age, associated with germline heterozygous mutations of CDH1, MAP3K6 and CTNNA1 genes. In early stages it presents with non-specific and vague symptoms, in advanced stages it may cause nausea and vomiting, dysphagia, loss of appetite, abdominal mass or weight loss. Women have an increased risk of lobular breast cancer as well.