Purpose or Case Report: Pulmonary haemorrhage in children is a non-specific response to a number of varying insults. Many of these insults favour particular anatomic foci along the pulmonary and bronchial arterial trees respectively. Although recent years have seen an emerging interest in the understanding and classification of pulmonary vasculitides, this pathophysiology represents only one subset of the causes of pulmonary haemorrhage in children. Our purpose is to review the imaging and pathophysiologic manifestations of varying causes of pulmonary haemorrhage according to the anatomic region of susceptibilities in the pulmonary arterial and bronchial artery trees.

We aim to provide a perspective of imaging manifestations of the pathophysiologies of pulmonary haemorrhage displayed schematically according to their relative anatomic areas of susceptibility. We aim to focus on useful constellations or associated findings that will serve to help the reader differentiate amongst entities that often have otherwise similar imaging presentation.
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Conclusions: Pulmonary haemorrhage can present in paediatric patients of all ages. Understanding of the main pathophysiologic mechanisms that can occur in different subsets of patients can help radiologists to provide a more targeted differential diagnosis to guide clinical teams and to direct further imaging recommendations in some cases.