Upper Lung Zone Disease Distribution
Jud W. Gurney, MD, FACR
DIFFERENTIAL DIAGNOSIS
Common
Post-Primary Tuberculosis
Sarcoidosis
Centrilobular Emphysema
Bronchiolitis, Respiratory
Langerhans Cell Histiocytosis
Less Common
Silicosis/Coal Worker’s Pneumoconiosis
Chronic Hypersensitivity Pneumonitis
Cystic Fibrosis
Chronic Eosinophilic Pneumonia
Allergic Bronchopulmonary Aspergillosis
Rare but Important
Neurogenic Pulmonary Edema
Smoke Inhalation
Metastatic Pulmonary Calcification
Ankylosing Spondylitis
Chronic Lung Allograft Rejection
ESSENTIAL INFORMATION
Key Differential Diagnosis Issues
Pneumonic: CHEST CASES
Cystic fibrosis, Histiocytosis X or Hypersensitivity pneumonitis, Emphysema, Sarcoidosis, Tuberculosis
Calcification-metastatic pulmonary, ABPA or Ankylosing spondylitis, Silicosis, Eosinophilic pneumonia, Smoke inhalation
Normal physiologic gradients in upright lung create zones or regions of lung that differ in terms of blood flow, ventilation, lymphatic function, stress, and concentration of inhaled gases
Consider lung as a map, with zones not defined by anatomy but by regional differences produced by physiology
End result of interaction between pathologic process with its environment
Soil and seed concept: Seeds (pathologic process) finds certain soils (physiologic regions) more conducive to growth
Distribution of disease usually readily apparent from frontal radiograph
Caveats: Normally lung much thicker at base than at apex
Truly uniform distribution of pathology will be more apparent in lower lung zones due to summation across greater thickness of lower lobes
Uniform radiographic distribution may actually be more profuse in upper lung zones pathologically due to less summation across thinner upper lobes
Helpful Clues for Common Diagnoses
Post-Primary Tuberculosis
Proclivity for apical posterior segments of upper lobes
Cavitary disease combined with consolidation and bronchial wall thickening
Sarcoidosis
Chronic granulomatous process of unknown etiology
Peribronchial and perilymphatic nodules
Identical findings in berylliosis
Centrilobular Emphysema
Sequelae of long-term smoking
Punched out holes in centrilobular distribution
Bronchiolitis, Respiratory
Clustered “dirty” macrophages in and around respiratory bronchioles from cigarette smoking
Faint, ill-defined centrilobular nodules in upper lung zones
May be precursor of centrilobular emphysema
Langerhans Cell Histiocytosis
Granulomas contain Langerhans cell (that processes antigen)
Seen almost exclusively in smokers
Probably allergic reaction to constituent of cigarette smoke
Centrilobular nodules that eventually evolve into bizarre-shaped cysts, paracicatricial emphysema
Helpful Clues for Less Common Diagnoses
Silicosis/Coal Worker’s Pneumoconiosis
Long-term exposure to occupational dusts
Simple (nodular interstitial thickening) may progress to progressive massive fibrosis (PMF)
Nodules follow lung lymphatics, tends to be more profuse in dorsal upper lung
Chronic Hypersensitivity Pneumonitis
History of inhaled organic antigen exposure
Upper lung zone distribution, especially common in those with intermittent exposure (like farmer’s lung)
Midlung predominance seen in many other antigen exposures that occur continuously (like bird breeder’s lung)
Centrilobular ground-glass nodules and hyperinflated lobules (head-cheese sign) evolves into peribronchial fibrosis
Cystic Fibrosis
Autosomal recessive gene disorder that results in thick viscous secretions
Primary pathology occurs in airways
Bronchiectasis more severe in upper lobes, especially right upper lobe
Chronic Eosinophilic Pneumonia
Predominant involvement in upper peripheral lung (“photographic negative” of pulmonary edema)
Ground-glass opacities and consolidation
Opacities resolve from periphery, leaving lines (inner edge) paralleling chest wall
Rapid response to corticosteroid therapy
Allergic Bronchopulmonary Aspergillosis
Asthma history, abnormal hypersensitivity reaction to Aspergillus organisms
Central upper lobe bronchiectasis with peripheral sparing
Helpful Clues for Rare Diagnoses
Neurogenic Pulmonary Edema
Any central nervous system (CNS) insult that acutely raises intracranial pressure
Edema is due to both hydrostatic and capillary leak
Smoke Inhalation
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