What Causes Digital Clubbing?

Patient Presentation
A 4-year-old female came to the emergency room with fever and mild respiratory distress and cough. She had recently immigrated from Mexico. The past medical history was negative for surgeries and hospitalizations, and her immunizations were not current. The review of systems revealed that she had a poor appetite, poor growth, no sweats or actual weight loss. there was no hematemesis The social history showed that the family had been in several transitory housing situations over the past several months, where various residents had been ill with gastrointestinal illnesses and coughs.

The pertinent physical exam showed a tired-appearing female. She had a temperature of 38.2°, respiratory rate of 40, pulse of 118, and saturation of 87% on room air. Her weight was 50% for a 3.5 year old, and her height was 10% for age. HEENT showed copious rhinitis. Lungs had wheezing and crackles bilaterally. She had multiple lymph nodes in the anterior and cervical chains (all were <1.0 cm). No supraclavicular nodes. She also had several bilateral groin nodes (also all < 1.0 cm). Her hands showed bilateral clubbing of the digits. Her toes did not have clubbing. The work-up included a chest radiograph that was suggestive of tuberculosis. The diagnosis of suspected tuberculosis was made and she was admitted. Pulmonary tuberculosis was confirmed by a positive PPD and QFT gold test and the patient was started on medications. A respiratory viral panel also confirmed concomitant respiratory syncytial virus. Public health was contacted and they investigated the family and other potential contacts. Prior to discharge, the family was assisted in finding primary care home where followup and preventive care (including immunizations) would be given. At follow-up at 1 month, the patient was taking her medication and was improving.

Case Image
Figure 103 – PA and lateral radiographs of the chest (from another patient) demonstrate prominent bilateral hilar lymphadenopathy, which is suggestive of a diagnosis of tuberculosis. The lungs are otherwise clear.

Clubbing is a uniform swelling of the terminal digital phalynx with loss of the normal angle between the nail and nail bed (i.e. Lovibond angle). the earliest sign is periungual erythema, then filling in of the angle between the proximal nailbed and the soft tissue of the finger just beneath the cuticle. This usually has a normal angle of around 160 °. The angle then begins to straighten out (i.e. 180°) and the nail base has a floating or springy sensation when palpated. With late clubbing there is visible swelling and the angle exceeds 180° and tissues are shiny and tense. With severe clubbing there is swelling of the terminal part of the digit causing it to appear like a drumstick. Rounding and beaking of the distal nail bed in the absense of other signs of clubbing is familial and not indicative of disease. Clubbing is usually painless and patients and family members may not notice. Clubbing usually occurs bilaterally but can occur unilaterally.

The exact pathophysiological mechanism for each cause of clubbing is unknown but an increase in vascular endothelial growth factor appears to be an important common pathway. Vascular endothelial growth factor causes vascular hyperplasia, edema, and fibroblast or osteoblast proliferation in the distal nails.

For images of clubbing see To Learn More below in the image search.

Learning Point
Digital clubbing is not a common general pediatric problem, but certainly not uncommon in particular patient populations such as patients with congenital heart disease, cystic fibrosis and other chronic lung or gastrointestinal diseases.

The differential diagnosis of clubbing includes:

  • Cardiac
    • Congenital heart disease with cyanosis
    • Infective endocarditis
    • AV malformations
  • Endocrine
    • Acromegaly
    • Hyperthryoidism
    • Hyperparthryoidism
  • Gastrointestinal
    • Achalasia
    • Celiac disease
    • Cirrhosis
    • Crohn’s disease
    • Tropical sprue
    • Ulcerative colitis
  • Infectious disease
    • Tuberculosis
  • Pulmonary
    • Cystic fibrosis
    • Interstitial lung disease – particularly bronchiectesis, but this is a large differential diagnosis itself.
    • Abscess and empyema
    • Lung cancer – primary and metastatic
    • Sarcoidosis
  • Other
    • Hypertrophic osteopathy – primary and secondary
    • Malignancy
    • Palmoplantar keratoderma
    • Pregnancy
    • Pseudoclubbing

Questions for Further Discussion
1. What is the current treatment for pulmonary tuberculosis in the United States?
2. What initial laboratory evaluation would you do for clubbing?

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com, the National Guideline Clearinghouse and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for this topic: Finger Injuries and Disorders

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

Bates B. A Guide to Physical Examination. Third edition. J.B. Lippincott Co. Philadelphia 1983;53.

Avery ME, First LR. Pediatric Medicine. 2nd Edit. Williams and Wilkins 1989;259,486.

Rudolph CD, et.al. Rudolph’s Pediatrics. 21st edit. McGraw-Hill, New York, NY. 2003:1754.

Rajagopalan M, Schwartz RA. Evaluation of Clubbing. ePocrates Online.
Available from the Internet at https://online.epocrates.com/u/2912623/Evaluation+of+clubbing/Differential/Etiology (rev. 1/25/13, cited 3/4/13).

ACGME Competencies Highlighted by Case

  • Patient Care
    1. When interacting with patients and their families, the health care professional communicates effectively and demonstrates caring and respectful behaviors.
    2. Essential and accurate information about the patients’ is gathered.
    3. Informed decisions about diagnostic and therapeutic interventions based on patient information and preferences, up-to-date scientific evidence, and clinical judgment is made.
    4. Patient management plans are developed and carried out.
    7. All medical and invasive procedures considered essential for the area of practice are competently performed.
    8. Health care services aimed at preventing health problems or maintaining health are provided.

  • Medical Knowledge
    10. An investigatory and analytic thinking approach to the clinical situation is demonstrated.
    11. Basic and clinically supportive sciences appropriate to their discipline are known and applied.

  • Practice Based Learning and Improvement
    13. Information about other populations of patients, especially the larger population from which this patient is drawn, is obtained and used.

  • Systems Based Practice
    24. Cost-effective health care and resource allocation that does not compromise quality of care is practiced.
    25. Quality patient care and assisting patients in dealing with system complexities is advocated.
    26. Partnering with health care managers and health care providers to assess, coordinate, and improve health care and how these activities can affect system performance are known.


    Donna M. D’Alessandro, MD
    Professor of Pediatrics, University of Iowa Children’s Hospital