Clubbing. The hands of an elderly patient showing clubbing (acropachy) around the fingertips. The fingertips appear bulbous and shiny, with unusual- ly curved, rounded fingernails. Clubbing affects the fingers and the toes. It often occurs in patients with lung disease (such as lung cancer, tuberculosis, bronchiectasis, emphysema and alveo- litis) or heart abnormalities that cause cyanosis, a bluish complexion due to lack of oxygen in the blood. Clubbing is also occasionally associated with the intestinal diseases Crohn's disease and ulcerative colitis, and it can also occur as a harmless, inherited abnormality.