beta-catenin expression in the transitional cell zone of pilomatricoma

Background beta -Catenin, a participant in the Writ pathway, has been shown to play an important role in the morphogenesis of hair follicles and the f ormation of hair follicle-related tumours, including pilomatricomas. It has been observed that at least 75% of human pilomatricomas possess activating mutations in beta -catenin. These findings suggested that beta -catenin pl ays an important role in the tumorigenesis of pilomatricomas. However, the pattern of beta -catenin expression in pilomatricoma tissues is still uncle ar. Objectives To examine the expression of beta -catenin in human pilomatricom as by immunohistochemical staining. Methods Twenty-six formalin-fixed and paraffin-embedded samples of pilomatr icoma tissue were studied. Results Most transitional cells of pilomatricoma expressed beta -catenin st rongly, but the basophilic cells and shadow cells did not. beta -Catenin sh owed a prominent membranous immunoreactivity and a small amount of condense d cytoplasmic staining, but there was definitely no evidence of nuclear pos itivity. Conclusions These findings imply that beta -catenin is primarily involved i n cell-cell adhesion rather than cellular proliferation during pilomatricom a pathogenesis, and suggest that if beta -catenin is involved in pilomatric oma tumorigenesis and tumour growth, it plays an indirect role.