Enlargement of the distal segments of the fingers and toes that result in a convex distal phalanx.

Characterized by enlargement of the terminal segments of the fingers or toe, resulting from connective proliferation between the nail matrix and the distal phalanx.

Schamroth sign: obliteration of diamond shaped window produced when the dorsal surfaces of the corresponding finger of each hand are opposed.


Associated with elevation of the nail and widening of the distal phalanx caused by swelling of the subungual capillary bed resulting from increased collagen deposition, interstitial inflammation, and proliferation of the capillaries.

Associated with perivascular infiltrates of lymphocytes and vascular hyperplasia that cause thickening of vessel walls.

Electron microscopy reveals Weibel-Palade bodies and prominent Golgi complexes, arteriovenous anastomoses confirming structural vessel wall damage.

Not usually seen with chronic obstructive pulmonary disease or asthma.

Associated with lung disease such as pulmonary fibrosis, lung cancer, bronchiectasis,cystic fibrosis and lung abscesses, and non-pulmonary processes including cyanotic congenital heart disease, infective endocarditis, inflammatory bowel disease and cirrhosis.

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