- Unlike systemic Langerhans cell histiocytosis or that confined to bone (eosinophilic granuloma) which is seen in paediatric population, pulmonary LCH is usually identified in young adults (20-40 years of age).
- Almost always there is a history of smoking.
- There is proliferation of Langerhans cells in the bronchiolar and bronchial epithelium, forming granulomas –> these cellular granulomas evolve, peripheral fibrosis forms resulting in traction on the central bronchiole which becomes cyst-like –> explains the evolution from nodule to thick-walled cyst and finally to thin walled cyst.
– Langerhans cells are dendritic cells (antigen-presenting immune cells) of the skin and mucosa,
- X ray is often non-specific, showing bilateral reticulonodular pattern with upper lobe predominance.
– Predilection for the mid and upper zones and regional sparing of the costophrenic recesses, anterior right middle lobe and lingula left upper lobe.
– Nodules are often centrilobular
– With time they cavitate & become cysts. The thin walled cysts can coalesce and become irregularly shaped.
- Treatment: the only effective method is STOP SMOKING !! It is reversible by smoking cessation.
- Complication: pneumothorax (from cysts rupture)
- Irregular cysts and nodules (which may cavitate) with upper lung predominance in a smoker should raise suspicion for the diagnosis
Reference: radiopaedia.org, auntminnie.com