CT appearance of Pulmonary Langerhans Cell Histiocytosis (LCH) and approach to imaging of cystic lung diseases
Pulmonary LCH is a rare disease found almost exclusively in cigarette smokers.
Radiologic findings of pulmonary LCH include
- Nodules, usually smaller than 1 to 5 mm, centrilobular, and peribronchiolar, may be cavitary, may be seen in association with cysts.
- Thick-walled or thin-walled cysts. – Progression over time from nodules to thick-walled cysts to thin-walled cysts.
- Upper lobe predominance in size and number of nodules or cysts, costophrenic angles spared.
- It can be associated with lymphadenopathy.
Pulmonary LCH vs lymphangioleiomyomatosis radiology
| Imaging features of Pulmonary Langerhans Cell Histiocytosis | Imaging features of Lymphangioleiomyomatosis |
|---|---|
| – Thick-walled, or thin-walled cysts – Nodules, usually smaller than 1 to 5 mm, centrilobular and peribronchiolar, may be cavitary, may be seen in association with cysts – Progression over time from nodules to thick-walled cysts to thin-walled cysts – Upper lobe predominance in size and number of nodules or cysts, costophrenic angles spared – Fine reticular opacities – Ground-glass opacity – Mosaic perfusion or air trapping – Pulmonary hypertension | – Thin-walled lung cysts, usually round in shape – Diffuse distribution, costophrenic angles involved – Mild septal thickening or ground-glass opacity – Lymph node enlargement – Small nodules in patients with TSC – Pleural effusion – Pneumothorax |
Common causes of cystic lung disease
Common (not truly cystic lung diseases but often confused as cysts)
- Emphysema (e.g., bullae) – Thin imperceptible walls.
- Cystic bronchiectasis
- Honeycombing
Less Common
- Pulmonary Langerhans Cell Histiocytosis
- Lymphangioleiomyomatosis (isolated LAM or associated with the TSC)
- Lymphocytic interstitial pneumonia (LIP) – Associated with Sjogren’s, AIDS, SLE
- Cystic metastases
- Pneumatoceles –
- Birt-Hogg-Dube syndrome = Lung cysts and renal oncocytomas.
Approach to imaging of cystic lung diseases
Reference: A Stepwise Diagnostic Approach to Cystic Lung Diseases for Radiologists
Watch the video for the detailed case discussion and PACS based image stack.
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