Pachydermoperiostosis-critical analysis with report of five unusual cases.

Pachydermoperiostosis (idiopathic hypertrophic arthropathy) {MIM 167100} is an uncommon disease characterized by unique phenotype (digital clubbing and pachydermia) and distinctive radiographic appearances (periostosis). Two families are reported that, in additional to the typical phenotype and radiographic characteristics of pachydermoperiostosis, show some rare and/or unusual, not yet reported, clinical findings. In the first family, distinctive features were severe progressive arthritis with villonodular involvement of the knees.