Clubbing

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Top Contributors - Kalyani Yajnanarayan

This article is currently under review and may not be up to date. Please come back soon to see the finished work! (1/06/2022)

Definition/Description

Distal clubbing is the uniform swelling of the soft tissue of the distal phalanx of a digit. Commonly this occurs bilaterally, however, can be occasionally unilateral in presentation (eg. brachial arteriovenous malformations, axillary artery aneurysm). Often distal clubbing is painless unless associated with underlying conditions such as pulmonary hypertrophic osteoarthropathy. While patients are often unaware of its presence, an understanding of its causation alerts healthcare professionals to the significance of this sign and the need for further investigation.

Pathophysiology

Over time, multiple hypothesis have been proposed to illustrate the pathophysiology of digital clubbing. The primary pathogenic finding is increased capillary density.

Mechanism of Injury / Pathological Process

Clubbing is often associated with numerous gastrointestinal and cardiorespiratory diseases. Such as:

• Lung cancer
• Cystic Fibrosis
• Bronchiectasis
• Idiopathic pulmonary fibrosis
• Endocarditis
• Congenital heart disease
• Ulcerative colitis
• Crohn's disease
• Liver disease (primary biliary cirrhosis)
  

Clinical Presentation

Stages of digital clubbing.

stage 1: peri-ungual erythema and softening of nail bed

stage 2: increase in the normal 160° angle between the nail bed and the proximal nail fold occurs, resulting in convexity as the nails grow. Eventually, the depth of distal phalanx increases and distal inter-phalangeal joint may become hyper-extensible. At this stage, finger develops a clubbed appearance

Stage 3: Finally, the nail and peri-ungual skin appear shiny and nail develops longitudinal ridging. This whole process usually takes years but in certain conditions, clubbing may develop sub-acutely (e.g. lung abscess, empyema thorasis).

Diagnostic Procedures

As there's no "gold standard" for the evaluation of clubbing, healthcare professionals must rely on their clinical examination skills to verify the diagnosis. Palpation and visual examination are usually sufficient to diagnose advance clubbing, however, early stages are more difficult to detect.

The schamroth sign is the absence of the diamond shaped "window" that normally occurs when the dorsal surfaces of the distal phalanges on opposing fingers are placed together. With palpation, the nail may seem loose within the soft tissue and in advance stages the proximal edge of the nail can be felt through the skin.

The nail-fold angle is one method of diagnosing clubbing. In asymptomatic fingers, the nail extends at approximately 160 degrees from the bed, however, in clubbed fingers the angle approaches 180 degrees.

The phalangeal-depth ratio is also used to differentiate normal nails to clubbed nails. In distal clubbing, the interphalangeal depth is smaller than the distal phalangeal depth. Healthcare professionals usually estimate the phalangeal depth ratio as calipers are not readily available.

Outcome Measures

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Management / Interventions

The primary focus of treatment of digital clubbing isn't on the clubbing itself but the underlying etiology if present.

Differential Diagnosis

Common differential diagnosis:

• Lung cancer
• Bronchiectasis
• Lung abscess
• Empyema

Uncommon differential diagnosis:

• Cystic fibrosis

• Interstitial pulmonary fibrosis
• Sarcoidosis
• Asbestosis

Resources

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