On CT chest, 'crazy paving' pattern is described as ground-glass opacity superimposed on thickened interlobular septa and intralobular lines. Which of the following conditions can produce this pattern?
- A Pulmonary alveolar proteinosis (PAP) only
- B PAP, PCP, COVID-19 pneumonia, lipoid pneumonia, and pulmonary haemorrhage ✓
- C Only infectious pneumonia — bacterial or viral
- D UIP pattern of IPF exclusively
Explanation
Crazy paving pattern — ground-glass opacity with superimposed thickened interlobular and intralobular septa creating a 'cobblestone' appearance — is classically described in pulmonary alveolar proteinosis (PAP) but is not pathognomonic. It occurs in Pneumocystis carinii pneumonia, COVID-19 ARDS, lipoid pneumonia, pulmonary haemorrhage, acute interstitial pneumonia (Hamman-Rich syndrome), mucinous adenocarcinoma, and sarcoidosis. Recognition that crazy paving is a nonspecific CT pattern requiring clinical correlation prevents misdiagnosis. UIP/IPF shows honeycombing and traction bronchiectasis without this pattern.
Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.
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Written and medically reviewed by the StethoPrep medical team.