Pulmonary haemorrhage and haemoptysis — short-answer question

Part A — Recognition, mechanism and confirmation (10 marks)

a) Explain why lung bleeding must be considered even though she has never coughed up blood (3 marks)

Young children rarely produce frank haemoptysis because they lack an effective adult cough and tend to swallow blood-stained airway secretions rather than expectorate them. Substantial diffuse alveolar haemorrhage therefore commonly shows itself as an iron-deficiency anaemia with breathlessness and shifting pulmonary infiltrates rather than as visible blood. Her iron-refractory microcytic anaemia with changing bilateral infiltrates is diffuse alveolar haemorrhage until proven otherwise. ^{[1] [2]}

b) Describe the mechanism that produces her anaemia and the diagnostic hallmark (4 marks)

Red blood cells that escape into the alveolar spaces are engulfed by alveolar macrophages, which break down the haemoglobin and store its iron as haemosiderin over roughly two to three days, producing haemosiderin-laden macrophages. Because that iron is trapped in the macrophages and effectively lost from the circulation, recurrent bleeding produces an iron-deficiency, microcytic anaemia even though no blood leaves the body. The haemosiderin-laden macrophage is the fingerprint of alveolar bleeding. ^{[1] [2]}

c) State how you would confirm alveolar bleeding in a child of this age (3 marks)

I would confirm alveolar haemorrhage by demonstrating haemosiderin-laden macrophages, ideally on bronchoalveolar lavage that also returns progressively bloodier aliquots. In a young child who cannot expectorate, an early-morning gastric aspirate showing the same haemosiderin-laden macrophages is a useful, less invasive alternative because swallowed blood is recovered from the stomach. ^{[2] [1]}