Crazy paving refers to the appearance of ground-glass opacities with superimposed interlobular septal thickening and intralobular septal thickening, seen on chest HRCT or standard CT chest. It is a non-specific finding that can be seen in a number of conditions.
Pathology
Etiology
Common causes:
pulmonary edema (most common)
acute interstitial pneumonia: ARDS of unknown etiology
pulmonary alveolar proteinosis (PAP): the great majority of patients with PAP demonstrate crazy paving
Less common causes:
usual interstitial pneumonia (UIP) with superimposed diffuse alveolar damage
cryptogenic organizing pneumonia (COP, formerly BOOP)
invasive mucinous adenocarcinoma of the lung (formerly mucinous bronchoalveolar carcinoma)
sarcoidosis, especially alveolar sarcoidosis