Differential Diagnosis #2: Cavitary Lung Disease

Today's Daily Diff is for cavitary lung disease. Cavitation can occur in the lung for many reasons. To remember the causes, think about big groups first, and just remember what you are looking at - a CAVITY:

C	Cancer (squamous cell carcinoma, melanoma, sarcoma mets)
A	Autoimmune (Wegener's granulomatosis, rheumatoid lung)
V	Vascular (ie bland or septic emboli)
I	Infection (TB, fungal (coccidioidomycosis, aspergillosis), bacterial (Staph, strep, Klebsiella))
T	Trauma
Y	Youth (ie congenital: bronchogenic cyst, sequestration)

To help narrow your differential diagnosis, consider the thickness of the cavity's wall. If the thickness is greater than 10 mm, this favors a metastatic process; thinner walls are more likely to be secondary to the other causes, with infection being the most common. 

Cavitary disease in pulmonary TB
Source: Radiopaedia

Source: Radiopaedia