Lesson of the Month -: Membrane loss and aberrant nuclear localization of E-cadherin are consistent features of solid pseudopapillary tumour of the pancreas.: An immunohistochemical study using two antibodies recognizing different domains of the E-cadherin molecule

Aims: To examine the expression of E-cadherin in solid pseudopapillary tumours (SPT) of the pancreas using two monoclonal antibodies recognizing two different domains of the E-cadherin molecule. Methods and results: Twenty cases of SPT were collected and a tissue microarray (TMA) constructed. The TMA was stained with commercially available antibodies to E-cadherin and beta-catenin. All 20 cases displayed nuclear beta-catenin as well as aberrant E-cadherin expression. With the antibody that stains the cytoplasmic domain of E-cadherin (clone 36, BD Transduction Laboratories), all 20 cases demonstrated nuclear E-cadherin reactivity, whereas with use of the antibody that recognizes the extracellular domain (clone 36B5, Vector Laboratories), no reactivity was observed in any of the cases. Conclusions: This study shows that aberrant beta-catenin and E-cadherin protein expression occurs in 100% of SPT, is probably linked mechanistically to beta-catenin nuclear localization, and two distinct patterns of E-cadherin immunoreactivity are seen in SPT: nuclear (with the antibody against the cytoplasmic domain), or immunonegativity (complete loss) when stained with the antibody for the E-cadherin extracellular fragment.