Mosaic Pattern
Sudhakar Pipavath, MD
DIFFERENTIAL DIAGNOSIS
Common
Constrictive Bronchiolitis
Hypersensitivity Pneumonitis
Cystic Fibrosis
Pulmonary Arterial Hypertension
Less Common
Inflammatory Bronchiolitis
Rare but Important
Chronic Pulmonary Thromboembolism
ESSENTIAL INFORMATION
Key Differential Diagnosis Issues
Differentiating small airway disease from vascular disease-related mosaic pattern
Associated direct features of small airway disease, such as centrilobular nodules, bronchiolar wall thickening, bronchiolectasis, and bronchiectasis
Mosaic pattern from air-trapping shows diminished vascular caliber
Accentuation of mosaic pattern on expiratory scans
Pulmonary vascular diseases show markedly enlarged central pulmonary arteries as dominant feature
“Head cheese” sign
Presence of ground-glass opacity, normal lung and air-trapping
Helpful Clues for Common Diagnoses
Constrictive Bronchiolitis
Classic small airways disease associated with these clinical syndromes
Postinfectious: Patchy and bilateral
Swyer-James syndrome/McLeod syndrome: Classic description is unilateral disease but uncommon
Rheumatoid arthritis or other connective tissue diseases
Post lung transplant (bronchiolitis obliterans syndrome)
Chronic graft vs. host disease
Hypersensitivity Pneumonitis
Poorly defined centrilobular opacities or nodules; “head cheese” sign
Cystic Fibrosis
Extensive central and upper lung bronchiectasis and mucus plugging in younger patients
Pulmonary Arterial Hypertension
Enlarged central pulmonary arteries
Helpful Clues for Less Common Diagnoses
Inflammatory Bronchiolitis
Centrilobular nodules and tree in bud appearance are more common; acute or chronic airway infections most likely
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