Chest X ray Mnemonic: Cavitary Lesions

"If you see HOLES on chest X-ray, they are WEIRD": 

Histiocytosis
Oncological 
Lymphangioleiomyomatosis 
Environmental, occupational
Sarcoid

Wegener's syndrome
Embolic (pulmonary, septic)
Infection (anaerobes, pneumocystis, TB)
Rheumatoid (necrobiotic nodules) 
Developmental cysts (sequestration)