Clubbing

Background

• Painless enlargement of terminal phalangeal connective tissue
• Affects fingers > toes
• Increased vascular connective tissue proliferation
  • May be due to megakaryocyte escaping from lungs due to damaged pulmonary capillaries, travelling to distal capillaries, and subsequently releasing growth factors +/- increased PGE2

Clinical Features

Digital clubbing with cyanotic nail beds in an otherwise healthy-appearing, asymptomatic young adult with Tetralogy of Fallot.

• Bulbous enlargement of the ends of one or more fingers or toes
• Loss of the normal angle between the skin and nail plate and excessive sponginess of the nail base
• Frequently accompanied by cyanosis of the nail bed

Differential Diagnosis

Clubbing as a sign can be related to the following causes:

• Respiratory Conditions
  • Interstitial fibrosis
  • Bronchiectasis
  • Lung Cancer
  • Empyema
  • Cystic Fibrosis
• Other Systemic Conditions
  • Congenital Cyanotic Heart Disease
  • Endocarditis
  • Liver Cirrhosis
  • Chronic Diarrhea
• Hereditary
• Idiopathic

Evaluation

Workup

• Evaluate potential underlying conditions as above based on clinical context
  • CXR
  • CT Chest
  • ABG / VBG
  • Pulse oximetry
  • CMP
  • Echocardiogram

Diagnosis

• Hyponychial angle >190 degrees
• Schamroth Sign - absent window between proximal nailbeds when opposite fingers placed back to back indicates clubbing

Management

• Treatment of underlying condition can improve findings over time

Disposition

• Based on overall clinical stability and other underlying diagnoses

References

1. McGee S. Chapter 28: Inspection of the Chest. In: Evidence-Based Physical Diagnosis. 5th ed. Philadelphia, PA: Elsevier; 2022. p. 235–9.