Elementary Lesions

Cysts

Characteristics

A cyst appears as a well-defined round or oval-shaped parenchymal lucency bordered by a thin, regular wall (< 2 mm)
The adjacent pulmonary parenchyma can be strictly normal or present associated lesions: nodules, groundglass opacities, septal thickening, or reticular CT pattern

Diagnostic Orientation

Emphysema, bronchiectasis
To establish the diagnosis, it is important to check for associated signs: renal tumour, lymphangioma, chylothorax

Diagnostic orientations

1. Cysts

HRCT shows multiple cysts throughout the lung parenchyma in a young female patient. Note that the adjacent lung is unremarkable.

2. Cyst

72-year-old woman with Sjögren’s syndrome and lymphoid interstitial pneumonia. HRCT shows bilateral groundglass opacities and multiple thin-walled cysts.

3. Cyst - ground-glass opacities

34-year-old man, HIV positive at AIDS stage. Progressive dyspnea for 1 month. The HRCT shows diffuse groundglass opacification with cysts of variable size. Diagnosis of pulmonary jirovecii pneumonia was done on bronchoalveolar lavage.

4. Cyst - nodule

HRCT at the level of the upper lobes shows numerous micronodules, cavitated nodules, and cysts in a 32-year-old man curent smoker who developed langerhans cell histiocytosis.

5. Cyst - nodule

Sagittal reformation in the same patient shows the upper lobe distribution of parenchymal abnormalities

6. Cyst - nodule

The patient is a 28-year-old male, smoker, with langerhans cell histiocytosis. HRCT at the level of middle zone shows bilateral and symetrical abnormalities of the lung parenclyma consisting in nodules, cavitated nodules, and cysts.

7. Cyst - nodule

Same patient - coronal reformation shows that the abnormalities are predominating in the upper lungs.

8. Cysts with "bizarre shape"

Sagittal reformation in a 58-year-old patient who was a former smoker and developed langerhans cell histiocytosis. HRCT shows large cysts with bizarre shapes.