IMAGE OF THE WEEK

WEEK 31

EARLY DIGITAL OR FINGER CLUBBING

Finger clubbing is characterised by the increase longitudinal curvatures of the nails in association with increase bogginess of the nail beds. Clubbing occurs in stages (Figure 1);

-       Periungual erythema and softening of the nail bed (spongy feeling on palpation)

-       Increase in the normal 160-165^o angle between the nail bed and proximal nail fold (Lovibond’s angle) (Figure 2)

-       Increase nail curvature (secondary to the increase Lovibond’s angle)

-       Enlargement giving the drumstick appearance

-       Shiny appearance of the periungual skin and the nail and longitudinal ridging of the nail

Clubbing may be associated with enlargement of the wrist joints (hypertrophic osteoarthropathy-HOA) characterised by periostosis of long bones and pain. It is also referred to as ‘Piérre Marié-Bamberger syndrome’.

Digital or finger clubbing is also known as ‘nail clubbing’, ‘drumstick fingers’, ‘Water-glass nails’ for the resemblance and ‘Hippocratic fingers’ after Hippocrates who described it in a patient with empyema.

Unilateral clubbing is associated with strokes with resultant hemiplegia and vascular lesions of affected side (arteriovenous fistula for dialysis, aneurysm or inflammatory).

Bilateral finger clubbing is commonly associated with neoplastic or chronic suppurative or inflammatory thoracic (asbestosis, cryptogenic fibrosis, idiopathic pulmonary fibrosis, hypersensitivity pneumonitis, pulmonary arteriovenous malformations, sarcoidosis etc...) and cyanotic cardiac disorders and infective endocarditis. It can also be associated with other gastrointestinal (inflammatory bowel disease, chronic hepatitis and celiac disease), infectious (tuberculosis, infective endocarditis and chronic suppurative thoracic infections that include empyema, chronic bronchiectasis and abscess), endocrine (thyroid disease), multiple systemic diseases or rarely even in that of psychiatric origin may show the sign, but generally less common.

It is also found in healthy population- ‘idiopathic clubbing’. It is now believed this may actually be the incomplete form of primary HOA or pachydermaperiosteosis, an autosomal dominant disorder that presents in childhood with clubbing, periostosis, and skin manifestations (Facial and scalp skin thickening, hyperhidrosis and seborrhoea).

The complete pathogenesis is unclear but involves vasodilatation, hypervascularisation and proliferation of tissue in the nail bed region secondary to effects of growth factors. Platelet derived growth factor (PDGF) released by impacted megakaryotes trapped in digital microcirculation lead to hypervascularisation. Megakaryocytes are normally fragmented into platelets in the lungs and in disrupted pulmonary circulations from lung disorders, fragmentations do not occur. Vascular endothelial growth factor (VEGF) is also involved in the pathogenesis. However other factors are involved to account for finger clubbing associated with other non pulmonary of cardiac disorders. Other proposed that cyanosis is important in the pathogenesis.

Images contributed by Dr Onn Lih Vei and edited by Dr Chong Vui Heng, Department of Internal Medicine, RIPAS Hospital, Brunei Darussalam.

All images are copyrighted and property of RIPAS Hospital.