Key points:
- Lung cancer is the most common pulmonary cause of finger clubbing.
- Most patients are unaware of the presence of finger clubbing.
- Clinician recognition of finger clubbing and appropriate investigation can be vital for treatment outcomes.
- NICE recommends an urgent chest X-ray (to be done within 2 weeks) for patient’s aged 40 and over who present with finger clubbing.
- Scottish Referral Guidelines for Suspected Cancer recommend an urgent chest X-ray for patients with a presentation of new or not previously documented finger clubbing.
Finger clubbing and lung cancer
Finger clubbing is a clinical sign that can be associated with multiple systemic diseases, this includes lung cancer and mesothelioma. It can be easily overlooked in the earlier stages, occurring in 35% of people with non-small cell lung cancer and 4% of people with small cell lung cancer.
The process of finger clubbing is not fully understood but it is thought to be caused by fluid collecting in the soft tissue of the fingers, due to increased blood flow to the area. It is felt that this may be a paraneoplastic process.
Pitfalls: Few patients recognise clubbed fingers to be a sign of cancer.
Most patients are unaware of the presence of finger clubbing. It can present alone with no additional symptoms and in the later stages it may be mistaken for arthritis. As clinicians, it is important for us to refer patients with finger clubbing for an urgent chest X-ray to assess for lung cancer.
Helpful hint: Finger clubbing occurs in stages.
- First there is softening of the nail bed and erythema of the skin around the nail.
- Then the nail begins to curve more than normal, this is called Schamroth’s sign.
- The nail and the skin around the nail also develop a shiny appearance.
- Then the ends of the fingers can become larger and form a drumstick appearance.
- In the more progressive cases, extra areas of bone can form on the finger joints and on the distal ends of long bones. This can be mistaken for arthritis and is known as hypertrophic osteoarthropathy. Hypertrophic osteoarthropathy is nearly always associated with finger clubbing, particularly with intrathoracic malignancies.
Practice takeaway:
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