Finger Clubbing

Clubbing is painless soft-tissue swelling of the terminal phalanges. The enlargement increases convexity of the nail. It may be produced by growth factors from megakaryocytes and platelets lodged in nail bed capillaries stimulating vascular connective tissue.
It is an important sign of major diseases, although it
may be congenital. It usually takes weeks or months to develop, and may disappear if the underlying condition is cured. Clubbing usually affects the fingers symmetrically, but may involve the toes. Unilateral clubbing can be caused by proximal vascular conditions, e.g. arteriovenous shunts for dialysis. Autoimmune hyperthyroidism may be associated with thyroid acropachy-clubbing which is more pronounced on the radial side
of the hand.