Desmoglein 3 Antibody (DSG3) is a component of desmosomes in vertebrate epithelial cells. This protein has been identified as the auto antigen of the skin blistering disease pemphigus vulgaris. Lung studies have shown that DSG3 had a sensitivity and specificity of 83% and 100%, respectively, in detecting squamous cell carcinoma (SqCC) vs. adenocarcinoma. Thus, DSG3 is a first class marker for lung SqCC and can be a useful ancillary marker to separate SqCC from other subtypes of lung cancer. Other studies have shown that DSG3 antibody expression in lung SqCC indicated a poor prognosis and portends a more aggressive clinical outcome.