Table 19.9.

Differential diagnosis of intrapulmonary lesions with air-fluid levels

Pathogenesis	Differential Diagnosis
Infection	– Staphylococcal infection; possibly accompanying pneumatoceles, no characteristic distribution pattern – Tuberculosis; usually thick walled and commonly in the upper lobes – Aspergillosis – Echinococcus (Hydatid cysts) – Herpes viruses – Secondary infected bulla – Secondary infected bronchiectasis – Cryptococcosis
Tumours	– Bronchial carcinoma; mostly thick walled and located peripherally, solitary, uncommonly associated with satellite nodules – Metastases (most commonly necrotic metastatic colon carcinoma and squamous cell carcinoma) – Hodgkin’s Lymphoma
Granulomas	– Wegener’s granulomatosis (lesions up to 10 mm, not all lesions undergo cavitation, no typical distribution pattern) – Rheumatoid nodules (usually basal distribution)
Others	– Haematoma – Pulmonary infarction – Silicosis (usually in the upper lobes) – Intralobar sequestration