A conditioned chiefly characterised by thickening of the skin of the head and distal extremities, deep folds and furrows of the skin of the forehead, cheeks, and scalp, seborrhea, hyperhidrosis, periostosis of the long bones, digital clubbing, and spadelike enlargement of the hands and feet. It is more prevalent in the male, and is usually first evident during adolescence. It is believed to be inherited as an autosomal dominant trait.