Hereditary diffuse gastric cancer (HDGC) is associated with E-cadherin 1 (CDH1) germline mutations. In the present study, two unusual HDGC cases are described. Case 1 was a female with no family history of gastric cancer who developed Hodgkin's lymphoma at 19 years of age, and DGC at 32 years of age. Due to her young age (32 years), the patient was examined for CDH1 abnormalities and a deleterious mutation was identified. Her father and younger sister were identified to be carriers of the mutation. Case 2 was a 36-year-old female diagnosed with lobular breast cancer (LBC); her mother had LBC, and her grandmother had LBC and DGC. The molecular test was wild-type for breast cancer susceptibility genes 1 and 2; however, a large deletion in CDH1 was identified. At prophylactic gastrectomy, early DGC was identified. Early onset of DGC and LBC justifies testing for CDH1. A better knowledge of tumor natural history in carrier subjects is important to aid genetic counseling, in order to assess the surveillance time required prior to carrying out prophylactic surgery.
Keywords: cadherin 1; diffuse gastric cancer; genetic counseling; lobular breast cancer; signet ring gastric cancer.