Pachydermoperiostosis (primary or idiopathic hypertrophic osteoarthropathy) is a disorder characterized by the insidious development, usually during adolescence, of clubbing, cylindrical thickening of the legs and forearms involving soft tissues as well as bones; thickening and greasiness of the skin of the face, scalp, and forehead, with deep furrows, especially of the forehead and scalp (cutis verticis gyrata); and excessive sweating.1,2 Radiologically, there is a symmetrical, irregular, subperiosteal ossification of the long bones, especially distally. The condition appears to be inherited in an autosomal fashion; there is marked variability in expressivity, with men, generally, being more severely affected.3
In secondary clubbing (pulmonary osteoarthropathy), increased peripheral blood flow has been demonstrated repeatedly and has been thought to be induced by a vagal reflex mechanism, which is reversible.4,5 Since clubbing without pulmonary lesions is characteristic of pachydermoperiostosis, peripheral circulatory studies in this condition and comparisons with pulmonary osteoarthropathy are