Abstract: Objective To explore the relationship of gene mutation and protein expression of β-catenin with tumorigenesis of pilomatricoma.Methods Sixty-seven specimens of pilomatricoma were examined for β-catenin expression by immunohistochemistry.Genomic DNA was extracted from 23 specimens positive for nuclear β-catenin and 4 negative for nuclear β-catenin,then amplified and sequenced.The gene mutation of β-catenin was confirmed by subcloning and restriction endonuclease assay.Results Of the 67 specimens,49 were positive for β-catenin;basophilic cells were detected in 32 of the 49 positive specimens, among which,81%(26/32)displayed nuclear staining of β-catenin in basophilic cells.Sequence analysis revealed a mutation rate of 61%(14/23)in exon 3 of β-catenin.The mutations were located at or adjacent to the phosphorylation sites in exon 3 of β-catenin.However,no mutations were detected in the 4 specimens negative for nuclear β-catenin.Conclusion The gene mutation and nuclear expression of β-catenin may contribute to the tumorigenesis of pilomatricoma.

Key words: Pilomatricoma, Mutation, β-Catenin