Necrotizing sarcoid granulomatosis

Necrotizing sarcoid granulomatosis (NSG) is a rare systemic disease, characterized by sarcoid-like granuloma formation, vasculitis and variable degrees of necrosis. It is sometimes classified under the group of pulmonary angiitis and granulomatosis.

Terminology

This remains a controversial entity, as many authors group it as a type of sarcoidosis ^3,10. 

Epidemiology

It typically affects middle-aged or elderly individuals.

Clinical presentation

Dyspnea and chest pain may be present, but up to 25% of patients may be asymptomatic ⁶.

Pathology

While many believe that it may be a variant of sarcoidosis, its proper classification is under debate due to some of its features also being found in Churg-Strauss syndrome, granulomatosis with polyangitis and hypersensitivity pneumonitis ³. Due to this, its pathological diagnosis can be challenging.

Radiographic features

CT

Many features have been described, with the most common feature being subpleural predominant alveolar infiltrative like opacification without a lobar preference.

The reported features on CT chest include:

• parenchymal opacification with air bronchograms
• solitary or multiple pulmonary nodules 
  • may have regular or slightly irregular margins 
  • typically range from 2-4 cm in diameter. 
  • cavitation may occasionally be present 
• hilar or mediastinal adenopathy - normally not compressive 
• pleural disease
  • pleural thickening
  • pleural involvement with granulomata

Treatment and prognosis

It is considered to have more favorable prognosis when compared with other similar granulomatous diseases. No definitive single management strategy is advocated although the use of steroids, surgical resection for localized disease or sometimes watchful waiting are recommended.

History and etymology

It was first described in 1973 by Liebow.