| Upper Lobe Predominant |
Pulmonary Langerhans Cell Histiocytosis (PLCH) |
Irregular, bizarre cysts with associated nodules |
Young adult smokers, mid-upper zone predominance, spontaneous pneumothorax |
|
Centrilobular Emphysema (smoking-related) |
Lucencies without walls (pseudocysts) |
Long smoking history, no true cyst walls, upper zone predominance |
|
Sarcoidosis (advanced stage) |
Fibrotic changes with traction cysts |
Upper lobe fibrocystic disease, perilymphatic nodules, hilar LAD |
|
Post-TB or granulomatous sequelae |
Focal thin-walled cavities/cystic change |
History of TB or fungal infection, calcified granulomas or nodules |
| Lower Lobe Predominant |
Alpha-1 Antitrypsin Deficiency (A1ATD) |
Panacinar emphysema, wall-less lucencies |
Early-onset emphysema, liver disease, strong lower lobe bias |
|
Lymphocytic Interstitial Pneumonia (LIP) |
Thin-walled cysts + GGO + septal thickening |
Sjögren’s, HIV, autoimmune disease |
|
Follicular Bronchiolitis |
Peribronchial small cysts |
Often overlaps with LIP, associated with RA or autoimmune disorders |
|
Aspiration/infective sequelae |
Cystic bronchiectasis |
History of aspiration, GERD, neuromuscular disease |
| Diffuse (All Zones) |
Lymphangioleiomyomatosis (LAM) |
Uniform, thin-walled round cysts |
Women of childbearing age, Tuberous Sclerosis, renal angiomyolipoma |
|
Birt-Hogg-Dubé Syndrome (BHD) |
Basal and subpleural irregular cysts, variable size |
Skin fibrofolliculomas, renal tumors, spontaneous pneumothorax |
|
Pneumocystis jirovecii Pneumonia (PCP) |
Ground glass opacities ± small thin-walled cysts |
Immunocompromised host (esp. HIV/AIDS), ↑ risk of pneumothorax |
|
Amyloidosis |
Cysts ± nodules ± calcifications |
Systemic amyloidosis or MALT lymphoma context |
|
Light Chain Deposition Disease (LCDD) |
Multiple cysts ± nodules |
Plasma cell dyscrasia, renal dysfunction |
|
Congenital Pulmonary Airway Malformation (CPAM) |
Multiloculated cysts (may appear diffuse) |
Pediatric or incidental adult discovery, abnormal developmen |
