Crazy paving

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 respiratory distress syndrome (ARDS)

• bacterial pneumonia

• acute interstitial pneumonia: ARDS of unknown etiology

• pulmonary alveolar proteinosis (PAP): the great majority of patients with PAP demonstrate crazy paving

Less common causes:

• drug-induced pneumonitis

• radiation pneumonitis

• pulmonary hemorrhage / diffuse pulmonary hemorrhage

  • Goodpasture syndrome

• chronic eosinophilic pneumonia

• usual interstitial pneumonia (UIP) with superimposed diffuse alveolar damage

• pulmonary infections

  • mycoplasma pneumonia

  • obstructive pneumonia

  • tuberculosis

  • Pneumocystis jirovecii pneumonia (PCP)

  • COVID-19

  • pulmonary cryptococcosis ⁶

• cryptogenic organizing pneumonia (COP, formerly BOOP)

• invasive mucinous adenocarcinoma of the lung (formerly mucinous bronchoalveolar carcinoma)

• sarcoidosis, especially alveolar sarcoidosis

• lipoid pneumonia

• pulmonary veno-occlusive disease