Pachydermoperiostosis (PDP) is characterized by clubbing fingers, furrowing of the facial skin, and perio-steal hypertrophy. We report a case of a patient with PDP associated with severe arthritis of the knee and ankle joints. His serum C-reactive protein (CRP) levels were increased, and an analysis of serum and synovial fluid showed high levels of interleukin-6. These findings mean that there is some difficulty in distinguishing the disease from rheumatoid arthritis. While treatments such as nonsteroidal anti-inflammatory drugs, steroids, and colchicine were not particularly effective, the severe arthralgia was gradually relieved over a few years.
