CDH1 and undifferentiated carcinoma: A recent large-scale study separating subtypes according to their growth pattern (polypoid or non-polypoid, i.e., signet cell, mucinous and undifferentiated carcinoma) showed that there is a complete loss of E-cadherin in non-polypoid and undifferentiated carcinomas, and reduced expression in polypoid, with no evidence of malignant alteration or invasion in canine gastrointestinal tumors [20].