A patient exhibiting clubbing, courtesy Desherinka, via Wikimedia Commons
Clubbing is the term used to describe a finger that ends with an enlarged phalanx. It is caused by the excessive growth of soft tissues under the cuticle, which leads to fingertips that are thinner at the final joint than at the base of the nail. The condition may be present in chronic obstructive pulmonary disease, interstitial fibrosis of the lungs, cyanotic heart defects, and many other illnesses.
In DNR, House bluffs out a judge at a hearing by claiming that he notices clubbing in his fingers and urges him to see a doctor, if he has a family history of heart disease.
In Sports Medicine, House notices the patient's coach has clubbing in his fingers and surmises that the patient stole the coach's digitalis in a suicide attempt.
In Que Será Será, House notices the patient's fingers are clubbed, not just fat, which leads him to the idea that the patient might be suffering from cancer and not a metabolic disease.