What condition is characterized by a deformity of finger/nail due to chronic cyanosis?

The condition characterized by a deformity of the fingers and nails due to chronic cyanosis is clubbing. Clubbing refers to the enlargement of the terminal phalanges, or the tips of the fingers and toes, often resulting in a curved and broadened nail appearance. This physical change is typically associated with chronic hypoxia, where the body has a long-term deficiency of oxygen. Conditions that affect oxygenation, such as chronic lung diseases or congenital heart defects, can lead to clubbing.

The other options do not describe this specific deformity caused by chronic cyanosis. Digitalis rings are not a recognized condition related to cyanosis or finger deformities, but rather a potential effect of the medication digitalis on the heart. Raynaud's phenomenon involves episodes of reduced blood flow to the extremities, typically characterized by color changes in the fingers and toes, but it does not lead to the chronic deformity seen in clubbing. Fingernail fungus, while it can cause changes to the appearance of nails, is unrelated to cyanosis or deformities caused by systemic oxygen deficiency.