Bronchocentric Granulomatosis

Jud W. Gurney, MD, FACR

Key Facts

Terminology

Pathologic reaction characterized by bronchocentric necrotizing granulomatous process in which airway wall is replaced by granulomatous tissue and palisaded histiocytes
- Airway lumen usually filled with necrotic debris
- Multiple causes, divided into infectious and noninfectious (usually allergic)

Imaging Findings

HRCT: Peripheral bronchiectasis or mucus plugging
Nodule or mass lesions (60%)
- Size 2-6 cm, unilateral (60%), solitary (75%) (when multiple usually < 3 in number)
- Upper lobe location (60%)
Consolidation (30%)
- Lobar (25%); for those not lobar, usually consolidation greater than segment in size
Diffuse reticulonodular pattern (10%)

Top Differential Diagnoses

Pathology

Clinical Issues

Asthma (50%), tissue eosinophilia, fungal (Aspergillus) hyphae on biopsy, similar to ABPA
Nonasthmatic(50%), have neutrophils in lung lesions, no asthma, no microscopic evidence of fungi

Axial HRCT shows nodular consolidation clustered along the airways

. A larger area of consolidation has a spiculated margin

Macroscopic pathology slide shows dilated bronchus

surrounded by inflammatory tissue

. The bronchus is also obliterated by inflammatory tissue

TERMINOLOGY

Abbreviations and Synonyms

Bronchocentric granulomatosis (BCG), allergic bronchopulmonary aspergillosis (ABPA)

Definitions

Pathologic reaction characterized by bronchocentric necrotizing granulomatous process in which airway wall is replaced by granulomatous tissue and palisaded histiocytes
- Airway lumen usually filled with necrotic debris
- Multiple causes, divided into infectious and noninfectious (usually allergic)

IMAGING FINDINGS

General Features

Best diagnostic clue: Focal air-space mass or peripheral bronchiectasis and mucoid impaction
Patient position/location: Slightly favors upper lobes
Size: Air-space mass usually several cm in size
Morphology: Mass usually has spiculated margin

CT Findings

Nonspecific, 3 patterns
- Radiographic patterns same no matter which clinical presentation
Air-space findings
- Nodule or mass characteristics
  - Spiculated margin, 2-6 cm in size
  - Location: Upper lobes or superior segments of lower lobes
  - CT more sensitive for cavitation (air or fluid)
  - Contain air-bronchograms signifying air-space process
- Consolidation
  - Lobar with mild volume loss
  - Mucoid impaction
  - May have multilobar disease (contralateral upper lobe)
  - Central airways patent (if central obstruction, consider bronchogenic carcinoma, which may have a pathologic pattern of BCG in the postobstructive lung)
Airways findings
- Peripheral bronchiectasis or mucoid impaction
- Central airways normal
Other
- Mediastinal lymph node enlargement (< 10 mm short axis diameter) common
- Pleural effusions uncommon