Pulmonary Langerhans cell histiocytosis in children: a spectrum of radiologic findings.

Pulmonary Langerhans cell histiocytosis (PLCH) is a well known entity in adults but is exceedingly rare in children. It is better described in adults than in children. We describe the current understanding of PLCH in children and a spectrum of radiological findings of PLCH in the paediatric population. On high resolution computed tomography (HRCT), PLCH may have variable appearance depending on the stage of disease, ranging from small interstitial nodular opacities to multiple thin/thick walled cysts (often bizarre in shape), eventually leading to marked parenchymal fibrosis and honeycomb pattern. CT finding of PLCH is similar in adult and paediatric populations with the exception that lung base near the costophrenic angle is spared in adults but almost always involved in children.