Upper Lobe Lung Diseases - STAR CHASERS Mnemonic
S - Silicosis
T - Tuberculosis
A - Ankylosing Spondylitis
R - Radiation
C - Cystic Fibrosis
H - Hypersensitivity Pneumonitis, Histoplasmosis
A - Aspergillus/ABPA
S - Sarcoidosis
E - Eosinophilic pneumonitis
R - Regurgitant MV
S - Smoke inhalation
Etiology:
Lung Apex:
• Relatively overventilated (ratio of ventilation to perfusion: 3:1), and the base is relatively overperfused (ratio: 0.6:1).
• Therefore, conditions caused by inhalation of toxic substances primarily affect the apices of the lung.
• Lymphatics clear smaller particles
• Lymphatic particle clearance ↓ at the apices thus granulomatous disorders, such as tuberculosis or sarcoidosis, appear predominantly in the upper lobes
• Metabolic factors, such as regional uptake of oxygen, elimination of CO2 & pH in the lung, differ due to inequalities of the V/Q ratio. These factors contribute to the upper zone predisposition of conditions such as metastatic pulmonary calcification and tuberculosis.
• ↑ Mechanical stress of the pulmonary apices caused by a rigid chest cage may result in fibrobulous apical lesions, as in patients with ankylosing spondylitis.
Pulmonary Diseases With Upper Lobe Predominance:
• Inhaled injurious gases:
- Smoke inhalation
- Centrilobular emphysema
• Impaired mucociliary clearance:
- Cystic Fibrosis
• Inhaled particulates:
- Pneumoconioses
- Silicosis
- Coal worker pneumoconiosis
- Berylliosis
• Miscellaneous pneumoconioses:
- Hard metal disease, kaolinosis, bauxite pneumoconiosis, fuller’s earth disease
• Inhaled antigens:
- Hypersensitivity pneumonitis
- Allergic bronchopulmonary aspergillosis
- Chronic eosinophilic pneumonia
• Granulomatous diseases:
- Tuberculosis
- Sarcoidosis
- Langerhans cell histiocytosis
- Bronchocentric granulomatosis
• Abnormal perfusion kinetics:
- Right-sided localized pulmonary edema in acute mitral regurgitation
- Neurogenic pulmonary edema
• Metabolic diseases:
- Metastatic pulmonary calcification
• Increased mechanical stress:
- Ankylosing spondylitis
Ref: American Journal of Roentgenology. 2013;200: W222-W237. 10.2214/AJR.12.8961
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