see also:

• clinical signs

• emedicine for more details

• clubbing of the nails in association with lung infection was 1st described by Hippocrates
• mechanism is unclear

1. nail bed fluctuation
2. loss of the normal nail-cuticle angle (Lovibond angle which is normally 15deg)
3. clubbed fingertip appearance with increased convexity of nail
4. loss of normal skin creases, shiny change to nail and longitudinal striation of nail

• formerly known as hypertrophic pulmonary osteoarthropathy (HPOA)
• syndrome of clubbing, periostitis of the long bones, and arthritis
• primary form is usually familial and affects infants and adolescents primarily, with male:female ratio of 9:1
• secondary form mainly affects the elderly and is associated with an underlying pulmonary, cardiac, hepatic, or intestinal disease
• see emedicine

• idiopathic hereditary clubbing
  • genetic dominant trait
• pachydermoperiostosis
  • rare genetic disorder with pachydermia, digital clubbing, periostosis, mainly affecting young males
• primary hypertrophic osteoarthropathy (PHO)
  • rare genetic disorder with digital clubbing, subperiosteal new bone formation, and arthropathy
  • linked to mutations in the 15-hydroxy-prostaglandin dehydrogenase (15-PGDH) encoding gene HPGD

• chronic lung suppuration
  • empyema, etc
  • tuberculosis (TB)
• lung cancer - especially non-small cell tumours
• idiopathic pulmonary fibrosis
• infective endocarditis (including SBE)
• cyanotic congenital heart disease eg. patent ductus arteriosis (PDA)
• inflammatory bowel disease (IBD) - more common in Crohn's disease than in ulcerative colitis
• proctitis
• myelofibrosis