Nuclear and cytoplasmic localization of β-catenin in the nail-matrix cells and in an onychomatricoma.

beta-catenin plays an important role in hair morphogenesis. Previously, the nuclear and cytoplasmic localizations of beta-catenin were identified in hair-matrix cells. To evaluate beta-catenin expression in the nail matrix, we obtained human nail units. Immunohistochemistry for beta-catenin was used to evaluate sections of normal nail units and of sections from a single case of onychomatricoma. In the nail unit, beta-catenin was expressed in the nucleus and cytoplasm of the suprabasal nail-matrix cells. Of the other epithelial- cell types, only the cell membrane was beta-catenin-positive. In the nail tissue from the onychomatricoma case, beta-catenin was expressed in the nucleus and cytoplasm of the upper epithelial layers. Our result suggests that beta-catenin plays an important role in nail formation. In addition, beta-catenin expression in onychomatricoma supports the presence of nail-matrix cells in this condition. To our knowledge, this is the first report of beta-catenin expression in the nucleus and cytoplasm of the nail matrix.