[Cystic and cavitary lesions of the lung: imaging characteristics and differential diagnosis].

Gas containing lesions of the lung can be differentiated into cystic and cavitary lesions based on their imaging characteristics, which is helpful for differential diagnosis. The imaging features include number, size, thickness and smoothness of the walls, content, lesion distribution and occasional associated lesions. Some imaging features have characteristic diagnostic implications: mural nodule and meniscus sign. Cysts are characterized by thin and regular walls, less than 2 mm in thickness. The differential diagnosis includes: histiocytosis X, lymphangioleiomyomatosis, cystic metastases, septic emboli, pulmonary sequestration. Emphysema, honeycombing and cystic bronchiectases should also be considered. Cavitary lesion have thicker walls. The most frequent etiologies include abscess, cavitary tumors, mycobacterial infections and fungal infections.