[Idiopathic clubbing of the fingers. Pathogenetic mechanisms and differential etiologic diagnosis].

We report on a patient with marked clubbing of the fingers and toes with watch-glass deformity of the nails, diagnosed as idiopathic clubbing. New findings on the pathogenesis of clubbing provide evidence for the important role of cytokines, especially platelet-derived growth factor and tumor necrosis factor-alpha. The differential diagnosis includes, besides rare primary forms, clubbing in malignant neoplasias and chronic inflammatory diseases of the heart, the lung, the upper gastrointestinal tract and the liver. Clubbing can precede other symptoms of neoplasias by mouths and could be dependent on a genetic predisposition.