What is pachyonychia congenita? Pachyonychia congenita is a very rare disorder. It causes thick nails and painful calluses on the bottoms of the feet. In some cases, blisters also form on the palms of the hands.
What is tendinitis? Tendinitis is swelling and pain in a tendon, which is tissue that connects muscles to bones. It is a common condition, usually caused by repeated injuries to a tendon.