Crazy-Paving Pattern

Eric J. Stern, MD

DIFFERENTIAL DIAGNOSIS

Common

Less Common

Rare but Important

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

Crazy-paving definition: Combination of smooth interlobular septal thickening superimposed on areas of ground-glass attenuation
- Resembles paths made of broken pieces of stone
- Prevalence of pattern in those with diffuse lung disease (1%)
Radiology-pathology correlation
- Linear network due to thickening of interlobular septa
  - May also be due to preferential accumulation of material in periphery of airspaces
- Ground-glass opacities result from partial alveolar filling
Acute time course
- Edema, PCP, hemorrhage, AIP, DAD
Subacute or chronic time course
- PAP, COP, hemorrhage, BAC, lymphangitic carcinomatosis, lipoid pneumonia, chronic eosinophilic pneumonia
Focal crazy-paving pattern
- Hemorrhage, BAC, lymphangitic carcinomatosis, lipoid pneumonia
Topology
- Upper lung zones predominant
  - Chronic eosinophilic pneumonia
  - Pneumocystis pneumonia
- Basilar lung zones predominant
  - Edema
  - Cryptogenic organizing pneumonia
  - Lipoid pneumonia
Extent of crazy-paving pattern
- Greater number of segments involved, more likely PAP

Helpful Clues for Common Diagnoses

Pulmonary Alveolar Proteinosis (PAP)
- Classic disease with crazy-paving pattern, subsequently found in other diseases
- Crazy-paving pattern often has sharply marginated geographic distribution
- Widespread crazy-paving pattern not seen with other conditions
- Symptoms usually less severe than radiographic abnormalities
  - Nonproductive cough, dyspnea (fever less common)
Pneumocystis Pneumonia (PCP)
- Typically perihilar or upper lung distribution
- More severe in upper lung zones in patients on pentamidine aerosol prophylaxis
- May have pneumatoceles, which typically develop in periphery of upper lobes
  - Curiously, pneumatoceles only seen in those with HIV infection
- Cough, dyspnea, and fever
Acute Interstitial Pneumonia (AIP) and Diffuse Alveolar Damage (DAD)
- Cause severe respiratory failure requiring mechanical ventilation
- AIP: Progressive respiratory disorder of unknown etiology with DAD on biopsy
- ARDS: End result of multiple medical or surgical conditions with DAD on biopsy
- AIP more often symmetrical than ARDS
- Ground-glass opacities (and crazy-paving pattern) seen in all phases of DAD
  - Ground-glass opacities and consolidation are more common than crazy-paving pattern
Edema
- Crazy-paving pattern can be seen in both cardiogenic and noncardiogenic edema
- Cardiogenic edema worse in gravity-dependent locations
- Heart enlarged and pleural effusions common in cardiogenic edema
- Resolves rapidly with treatment

Helpful Clues for Less Common Diagnoses

Diffuse Alveolar Hemorrhage
- Hemoptysis (80%) and anemia common
- Acute onset with hemorrhage into alveolar spaces (results in consolidation or ground-glass opacities)
  - Blood removed from alveoli by macrophages (2-3 days)
  - Macrophages migrate into interstitium (septal thickening)
  - Macrophages removed by lymphatics (7-14 days)
  - Crazy-paving pattern may be seen when macrophages migrate into interstitium
- Distribution typically perihilar or diffuse
Eosinophilic Pneumonia
- Peripheral eosinophilic lung consolidation more common in chronic (90%) than in acute pneumonia
- Typically peripheral in lung
- Consolidation and ground-glass opacities more common than crazy-paving pattern
Cryptogenic Organizing Pneumonia (COP)
- Reverse halo sign: Foci of ground-glass opacification surrounded by halo of consolidation
- Opacities may be migratory, similar to eosinophilic pneumonia
- Consolidation and ground-glass opacities more common than crazy-paving pattern

Helpful Clues for Rare Diagnoses

Tags: EXPERTddx: Chest

Aug 8, 2016 | Posted by drzezo in CARDIOLOGY | Comments Off

Thoracic Key