History
The development of clubbing usually is gradual enough that many patients are unaware of its presence; however, some patients may report swelling of the distal portion of the digits, which may be bilateral or unilateral or may involve a single digit.
Although clubbing typically is painless, it rarely may present with pain in the fingertips.
Rapid postoperative resolution of clubbing in a few days was described in a patient with aortic and mitral valve replacement due to infective endocarditis. [10]
Hypertrophic osteoarthropathy may occur as an isolated calcaneal periostitis bilaterally. [11]
Finger clubbing may be a clue to an underlying systemic disorder, including vasculitis with chronic hepatitis C and type II mixed cryoglobulinemia. [12]
Physical Examination
Clubbing is a clinical finding characterized by bulbous fusiform enlargement of the distal portion of a digit (see the image below).
Clubbed fingernail.
When the profile of the distal digit is viewed, the angle made by the proximal nail fold and nail plate (Lovibond angle) typically is less than or equal to 160°. In clubbing, the angle flattens out and increases as the severity of the clubbing increases. If the angle is greater than 180°, definitive clubbing exists. An angle between 160-180° falls in a gray area and may indicate early stages of clubbing or a pseudoclubbing phenomenon.
Individuals without clubbing display a diamond-shaped window at the base of the nail beds when the dorsum of 2 fingers from the opposite hands are opposed. The distal angle between the 2 opposed nails should be minimal. In individuals with digital clubbing, the diamond window is obliterated and the distal angle between the nails increases with increasing severity of clubbing.
The nail moves more freely in patients with clubbing; therefore, the examiner may note a spongy sensation as the nail is pressed toward the nail plate. The sponginess results from increased fibrovascular tissue between the nail and the phalanx. The skin at the base of the nail may be smooth and shiny.
Obliteration in clubbed fingers of the diamond-shaped window normally produced when the dorsal surfaces of the corresponding finger of each hand are opposed (Schamroth sign) may useful for the identification of clubbing. [13]
Causes
Clubbing can be idiopathic or secondary to many underlying pathologies in various organ systems.
Causes of idiopathic or primary clubbing include pachydermoperiostosis, familial clubbing, and hypertrophic osteoarthropathy. [14, 15]
Causes of secondary clubbing include the following [16] :
-
Pulmonary disease - Lung cancer, [17] cystic fibrosis, interstitial lung disease, [18] idiopathic pulmonary fibrosis, [19] sarcoidosis, [20] lipoid pneumonia, empyema, pleural mesothelioma, pulmonary artery sarcoma, [21] lung hydatid cysts, [22] and pulmonary metastases (see Dermatologic Manifestations of Pulmonary Disease)
-
Cardiac disease - Cyanotic congenital heart disease, [23] other causes of right-to-left shunting, and bacterial endocarditis (see Dermatologic Manifestations of Cardiac Disease); a scoring system for empiric treatment of infective endocarditis includes clubbing [24]
-
Gastrointestinal disease - Ulcerative colitis, Crohn disease, primary biliary cirrhosis, cirrhosis of the liver, hepatopulmonary syndrome, [25] leiomyoma of the esophagus, achalasia, and peptic ulceration of the esophagus (see Dermatologic Manifestations of Gastrointestinal Disease) [26]
-
Skin disease - Pachydermoperiostosis, Bureau-Barrière-Thomas syndrome, Fischer syndrome, palmoplantar keratoderma, [27] and Volavsek syndrome
-
Malignancies - Thyroid cancer, thymus cancer, Hodgkin disease, [28] and disseminated chronic myeloid leukemia (POEMS [polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes] syndrome is a rare paraneoplastic syndrome secondary to a plasma cell dyscrasia in which clubbing may be seen. [29, 30] Other findings including peripheral neuropathy, organomegaly, endocrinopathy, monoclonal plasma proliferative disorder, skin changes, sclerotic bone lesions, Castleman disease, thrombocytosis, papilledema, peripheral edema, pleural effusions, ascites, and white nails.)
Hypertrophic osteoarthropathy in adults is often a sign of internal cancer. [34] Other stigmata may also be evident, such as acquired keratoderma taking on a yellow velvety appearance with accentuation of dermatoglyphic lines.
As a paraneoplastic syndrome, it is most commonly associated with non–small-cell lung cancer, although it may occur with metastatic melanoma and other cancers. [35] Hypertrophic pulmonary osteoarthropathy is evident in 1- 5 % of all patients with non–small-cell lung cancer. [36]
Among hemodialysis patients with end-stage renal disease, the finding of clubbing was linked with the calcium-phosphorus product. [37]
Nail changes in 100 chronic renal failure patients undergoing hemodialysis and 100 matched controls were assessed. [38] Nail disorders were more prevalent in the renal failure patients (76%) than in the control group (30%). The half-and-half nail was the most common finding (20%), followed by absent lunula, onycholysis, brittle nail, Beau lines, clubbing, longitudinal ridging, onychomycosis, subungual hyperkeratosis, koilonychias, total leukonychia, splinter hemorrhage, pitting, and pincer nail deformity.
Complications
Since clubbing is a clinical finding, no direct complications occur, except for cosmetic concerns. The complications of the underlying disease resulting in clubbing may be numerous considering the wide spectrum of diseases that are associated with clubbing. The discussion of these is beyond the scope of this article.
Patients with hereditary hemorrhagic telangiectasia may have develop pulmonary arteriovenous malformations, which may induce clubbing, cyanosis, and other findings, possibly leading to complications such as stroke or brain abscess if untreated. [39]
-
Clubbed fingernail.
