21st February 2025

A 45-year-old man presents with a 1-month history of worsening bilateral arm and leg pain, weight loss and fevers.

A 45-year-old man presents with a 1-month history of worsening bilateral arm and leg pain, weight loss and fevers. He has no significant past medical history but does report a 30-pack-year smoking history and a history of alcohol excess. Examination reveals finger clubbing but nothing else of note. A chest X-ray performed as part of his initial assessment demonstrates hyperinflated lung fields, with a 2 cm nodule in the upper zone of the left lung. Blood tests are normal apart from a mild normocytic anaemia.

What is the most likely cause of his clubbing?

Select the SINGLE most appropriate option from the list below. Select ONE option only.