The diagnostic value of β-catenin immunohistochemistry

β-catenin is a 92-kDa protein that binds to the cytoplasmic tail of E-cadherin. It acts in the nucleus to stimulate cell proliferation and is degraded by complexing with the adenomatous polyposis coli gene. When it is mutated, it is ineffectively degraded and results in unchecked proliferative activity that plays a role in a subset of neoplasms. When there are alterations in β-catenin degradation, it accumulates to a sufficient extent to be detected in the nuclei of tumor cells immunohistochemically, a feature that can be exploited in the differential diagnosis of selected neoplasms. Immunohistochemistry for β-catenin may be useful in the differential diagnosis of selected tumors of soft tissue, the gastrointestinal tract, including the pancreas, lung, and female genital tract.