Idiopathic hypertrophic osteoarthropathy without pachyderma.

There are two types of hypertrophic osteoarthropathy; (a) the secondary type, by far the most common and usually associated with bronchogenic carcinoma; and (b) the idiopathic type, a rare disorder occurring predominantly in males and not associated with any known disease process. Both may be associated with peculiar skin changes known as pachyderma. When idiopathic hypertrophic osteoarthropathy (IHOA) is associated with pachyderma it is called pachydermoperiostosis. In extremely rare instances, IHOA may occur without pachyderma. Three such cases are described.