Inducible Beta-Catenin Activation and PTEN Inactivation Elicit Follicular Tumors, Not Papillomas: A Potential Paradigm for Trichilemmomas in Cowden's Disease

The study investigated the effects of β-catenin activation and PTEN inactivation in mice, revealing that this combination led to follicular hyperplasia, cysts, and sebaceous gland hyperplasia, but not papillomas or squamous cell carcinoma (SCC). This was contrary to expectations, as β-catenin is known to be oncogenic when dysregulated. The findings suggested that increased p21 expression might inhibit AKT activation, preventing malignant conversion. The histopathology observed was similar to Multiple Trichilemmomas, a tumor associated with Cowden’s Disease, indicating a potential mechanism for its development. The study provided insights into the cooperation between deregulated β-catenin and PTEN signaling, suggesting a novel pathway for the aetiology of these follicular tumors.