Most common
• Bronchogenic Carcinoma (++)
• Pulmonary Infarction (++)
• T.B. (+)

Common
• Bronchiectasis
• Lung abscess (+ pus)
• Bronchitis (acute; chronic; COPD)

Uncommon
• Tumors of Trachea, Larync
• Bronchial Adenoma
• Lung secondaries

Others
• Chest trauma
• F.B.
• Iatrogenic