cystic lung disease

Cystic lung disease is an umbrella term used to group the conditions coursing with multiple lung cysts.

Clinical presentation

The clinical presentation is an important clue to the differential diagnosis of cystic lung diseases .

Diseases that present with insidious dyspnea or spontaneous pneumothorax:

Congenital cystic lung diseases that present with recurrent pneumonia or are asymptomatic:

Diseases that present with signs/symptoms of infection:

Multisystemic diseases that primarily present with extrapulmonary signs/symptoms:

Pathology

A lung cyst is a gas-filled structure with a thin perceptible wall, typically <2 mm in thickness but can be up to 4 mm. The diameter of a lung cyst is usually <1 cm. By conventional definition in the literature, a lung cyst can be distinguished from a cavity for which the wall thickness is greater than 4 mm. However, in practice, clear separation of the two entities can sometimes be difficult .

Etiology

Primary pulmonary disease where diffuse cysts are the predominant feature:

Acquired cystic lung disease or cysts as a secondary feature of a primary disease:

Radiographic appearance

CT

The approach to cystic lung disease centers around the appearance on high resolution CT and history .

Once the lucencies are found to be true cysts (thin walled), the location should be determined. Subpleural or intrapleural cysts include:

In contrast, intraparenchymal cysts are surrounded by lung parenchyma and can be further evaluated by their associated features:

Intraparenchymal cysts with associated ground glass opacities:

Intraparenchymal cysts with associated pulmonary nodules:

Most other causes of intraparenchymal cysts do not have associated findings and may be instead distinguished by their distribution:

Unifocal pulmonary cysts:

Multifocal pulmonary cysts :

Differential diagnosis

If the pulmonary lucencies in question are not true cysts (not thin walled airspaces), there are several considerations other than cystic lung disease: