Nail clubbing

Causes

Clubbing is associated with

• Lung disease:
  • Lung cancer
  • Interstitial lung disease most commonly idiopathic pulmonary fibrosis
  • Complicated tuberculosis
  • Suppurative lung disease: lung abscess, empyema, bronchiectasis, cystic fibrosis
  • Mesothelioma of the pleura
  • Sarcoidosis
• Heart disease:
  • Any disease featuring chronic hypoxia
  • Cyanotic heart defect (most common cardiac cause)
  • Infective endocarditis
  • Atrial myxoma (benign tumor)
  • Arteriovenous fistula or malformation
• Gastrointestinal and hepatobiliary:
  • Malabsorption
  • Crohn's disease and ulcerative colitis
  • Cirrhosis, especially in primary biliary cholangitis
  • Hepatopulmonary syndrome, a complication of cirrhosis
• Others:
  • Graves' disease (autoimmune hyperthyroidism) – in this case, it is known as thyroid acropachy
  • Familial and hereditary clubbing and "pseudoclubbing" (people of African descent often have what appears to be clubbing)
  • Vascular anomalies of the affected arm such as an axillary artery aneurysm (in unilateral clubbing)
  • Primary hypertrophic osteoarthropathy

Nail clubbing is not specific to chronic obstructive pulmonary disease (COPD). Therefore, in patients with COPD and significant degrees of clubbing, a search for signs of bronchogenic carcinoma (or other causes of clubbing) might still be indicated.

Hypertrophic pulmonary osteoarthropathy

Main article: Periosteal reaction

A special form of clubbing is hypertrophic pulmonary osteoarthropathy (HPOA), known in continental Europe as Pierre Marie-Bamberger syndrome. This is the combination of clubbing and thickening of periosteum (connective tissue lining of the bones) and synovium (lining of joints), and is often initially diagnosed as arthritis. It is commonly associated with lung cancer.

Primary hypertrophic osteoarthropathy

Primary hypertrophic osteoarthropathy is HPOA without signs of pulmonary disease. This form has a hereditary component, although subtle cardiac abnormalities can occasionally be found. It is known eponymously as the Touraine–Solente–Golé syndrome. This condition has been linked to mutations in the gene on the fourth chromosome (4q33-q34) coding for the enzyme 15-hydroxyprostaglandin dehydrogenase (HPGD); this leads to decreased breakdown of prostaglandin E2 and elevated levels of this substance.

Pathogenesis

The exact cause of sporadic clubbing is unknown. Theories as to its cause include:

• Vasodilation (i.e., distended blood vessels).
• Secretion of growth factors (e.g., platelet-derived growth factor and hepatocyte growth factor) from the lungs.
• Overproduction of prostaglandin E2 by other tissues.
• Increased entry of megakaryocytes into the systemic circulation. Under normal circumstances in healthy individuals, megakaryocytes that arise from the bone marrow are trapped in the pulmonary capillary bed and broken down before entering the systemic circulation. It is thought that in disorders where there is right-to-left shunting or lung malignancy, the megakaryocytes can bypass the breakdown within the pulmonary circulation and enter the systemic circulation. They are then trapped within the capillary beds within the extremities, such as the digits, and release platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF). PDGF and VEGF have growth-promoting properties and cause connective tissue hypertrophy and capillary permeability.

Diagnosis

When clubbing is observed, pseudoclubbing should be excluded before making the diagnosis. Associated conditions may be identified by taking a detailed medical history—particular attention is paid to lung, heart, and gastrointestinal conditions—and conducting a thorough clinical examination, which may disclose associated features relevant to the underlying diagnosis. Additional studies, such as a chest X-ray and a chest CT-scan, may reveal otherwise asymptomatic cardiopulmonary disease.

Stages

Clubbing is present in one of five stages:

• No visible clubbing – Fluctuation (increased ballotability) and softening of the nail bed only. No visible changes in nails.
• Mild clubbing – Loss of the normal
• Moderate clubbing – Increased convexity of the nail fold. Clubbing is apparent at a glance.
• Gross clubbing – Thickening of the whole distal (end part of the) finger (resembling a drumstick)
• Hypertrophic osteoarthropathy – Shiny aspect and striation of the nail and skin

Schamroth's sign or Schamroth's window test (originally demonstrated by South African cardiologist Leo Schamroth on himself) is a popular test for clubbing. When the distal phalanges (bones nearest the fingertips) of corresponding fingers of opposite hands are directly opposed (place fingernails of the same finger on opposite hands against each other, nail to nail), a small diamond-shaped "window" is normally apparent between the nailbeds. If this window is obliterated, the test is positive, and clubbing is present.

File:Clubbing of fingers.jpg|Severe clubbing Clubbing2.JPG|Front view Clubbing1.JPG|Side views CongenitalHeartCase-133.jpg|Cyanotic nail beds

Epidemiology

The exact frequency of clubbing in the population is not known. A 2008 study found clubbing in 1%, or 15 patients, of 1511 patients admitted to a department of internal medicine in Belgium. Of these, 40%, or 6 patients, had significant underlying disease of various causes, while 60%, or nine patients, had no medical problems after further investigation and remained well over the subsequent year.

History

At least since the time of Hippocrates, clubbing has been recognized as a sign of disease. The phenomenon has been called "Hippocratic fingers".

The Dutch painter Dick Ket had nail clubbing, as is seen from his paintings. He had an underlying disease, probably dextrocardia.

References

References

1. Rapini, Ronald P.. (2007). "Dermatology: 2-Volume Set". Mosby.
2. (14 May 2013). "Digital clubbing". Circulation.
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4. (January 2019). "Osteoarthropathy Hypertrophic". StatPearls Publishing.
5. "Clubbing of the Nails".
6. (July 2008). "Prevalence, aetiologies and significance of clubbing in a department of general internal medicine". Eur. J. Intern. Med..
7. (2019). "Nail Clubbing". StatPearls Publishing.
8. (1998). "Digital clubbing and lung cancer". Chest.
9. (1981). "Prospective study of periostitis and finger clubbing in primary biliary cirrhosis and other forms of chronic liver disease". Gut.
10. Naeije R. (March 2003). "Hepatopulmonary syndrome and portopulmonary hypertension". Swiss Med Wkly.
11. {{Cite GPnotebook. -724565997. acropachy
12. (August 2017). "Homozygous SLCO2A1 translation initiation codon mutation in a Pakistani family with recessive isolated congenital nail clubbing". Br. J. Dermatol..
13. (June 2008). "Mutations in 15-hydroxyprostaglandin dehydrogenase cause primary hypertrophic osteoarthropathy". Nat. Genet..
14. (19 December 1987). "Megakaryocytes and platelet clumps as the cause of finger clubbing.". Lancet.
15. (2001). "The rational clinical examination: does this patient have clubbing?". JAMA.
16. Schamroth L. (February 1976). "Personal experience". S. Afr. Med. J..
17. (in Dutch) [https://www.ntvg.nl/system/files/publications/1984124230001a.pdf Dick Ket, een schilder en zijn ziekte] W.H.D. de Haas, Nederlands Tijdschrift voor Geneeskunde, 1984