Crazy paving pattern

What is the crazy paving pattern?

This is a CT-related term that refers to presence of pulmonary ground glass opacity with superimposed interlobular septal thickening and intralobular lines, resembling irregularly shaped paving stones. The crazy paving pattern was originally associated with pulmonary alveolar proteinosis (PAP), but it can be seen in a wide variety of disease conditions including infection, hemorrhage, pulmonary edema, and some chronic disorders.