On high-resolution CT (HRCT) chest, the 'crazy paving' pattern (ground-glass opacification with superimposed inter- and intralobular septal thickening) is CLASSICALLY associated with which condition?

• A Pulmonary alveolar proteinosis (PAP) ✓
• B Usual interstitial pneumonia (UIP)
• C Lymphoid interstitial pneumonia (LIP)
• D Respiratory bronchiolitis-ILD (RB-ILD)

Explanation

The 'crazy paving' pattern — geographic ground-glass opacity with a superimposed network of interlobular and intralobular lines resembling crazy paving stones — is the classic HRCT pattern of pulmonary alveolar proteinosis (PAP). It represents alveolar spaces filled with PAS-positive lipoproteinaceous material. This pattern is not specific and can also be seen in ARDS, Pneumocystis jirovecii pneumonia, lipoid pneumonia, and mucinous adenocarcinoma. UIP shows honeycombing in basal subpleural distribution. LIP shows cysts and ground-glass. RB-ILD shows centrilobular nodules.

Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.