Patients history was remarkable only for recent dental work, which in lieu of any other source was presumed to be the original source of infection. Unfortunately, no specific organism was grown, but the patient presented with infective symptoms and biochemistry and responded clinically to a prolonged course of IV antibiotics. Screening and history for alternative causes were negative. Given the clinical course, the diagnosis was felt to be pulmonary abscesses.

Differential for cavitating lung lesions includes:

• infective: pulmonary TB, bacterial abscess, cavitating pneumonia, septic emboli
• autoimmune: granulomatosis with polyangiitis, rheumatoid nodules
• malignancy: primary and metastases
• pulmonary infarct
• pneumatoceles secondary to trauma (not a true cavity)
• congenital causes

The mnemonic device CAVITY is sometimes used.