Fact-sheet: Pulmonary Langerhans cell histiocytosis
Updated on 09/17/2021 at 12:16 PM
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Definition
Langerhans cell histiocytosis
Oligoclonal proliferation of Langerhans cells organized into granulomas:
- Histiocytes: monocytes migrate into connective tissue and differentiate
- Monocyte-macrophage or reticuloendothelial system
- Langerhans cells: cutaneous, mucosal, pulmonary histiocytes (CD1a+)
Clinical features
Estimated prevalence of 1 to 2 per 100,000
Young adult: 20-40 years
Heavy smoking history
Asymptomatic / Cough and fever / Spontaneous pneumothorax
Pulmonary function: decreased CO transfer, obstructive pattern.
If typical CT findings and active smoking: clinicoradiologic diagnosis.
Otherwise: - BAL: Langerhans cells > 5%
- Transbronchial biopsy: Langerhans cell granuloma
Radiography
. Normal Micronodules or nodules Reticulonodular opacities Interstitial pattern Cysts Honeycombing . Upper and middle lung predominance Sparing of the bases . Complication: pneumothorax
CT
. Recent lesions: nodules / cavitated nodules / thick-walled cysts .
Older lesions: thin-walled cysts / confluent, coalescent cysts .
Cysts: - size < 10 mm
- thick to thin walls
- upper lobe predominance (coronal images)
- sparing of the costophrenic angles
- tendency to coalesce .
Associated lesions: - centrilobular nodules and micronodules
- dense, ill-defined, or ground-glass
- cavitation .
Complications: pneumothorax, pulmonary hypertension, malignancy