Clubbing is a common disorder seen particularly with cardiopulmonary disease of any type. The aetiology is unknown but may be due to increased vascularisation, expression of growth factors, or overexpression of prostaglandins.
The clubbed finger is notable for increased width of the distal phalange and loss of the angle at the nail/finger interface. It can be tested for by placing the opposing nails of each finger together; if there is no diamond shaped gap then clubbing is present.
Clubbing can occur with numerous malignancies, but particularly lung cancer, lymphoma and occasionally gastrointestinal malignancies.