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. it 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.
Finger clubbing is present if:
• The interphalangeal depth ratio (B/A in Fig. 3.18) is >1
• The nail bed angle is >190°
• Schamroth’s window sign is absent. Increased nail bed fluctuation may be present, but its presence is subjective and less discriminatory than the above features.
Causes of Clubbing are includes.
• Thoracic (~70%)
• Lung cancer
• Chronic suppurative conditions
• Lung abscess
• Cystic fibrosis
• Pulmonary fibrosis
• Cyanotic congenital heart disease
• Infective endocarditis
• Arteriovenous shunts and aneurysms
• Inflammatory bowel disease
• Coeliac disease
• Thyrotoxicosis (thyroid acropatchy)