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 #Upperlobe #lung #diseases #differential #diagnosis #mnemonic #STARCHASERS #radiology
