Pneumonia, Acute Interstitial

Known clinically as Hamman-Rich syndrome

Wide age range, including many young patients

Acute onset of dyspnea followed by rapid development of respiratory failure

Preceding viral syndrome is reported by 50% of patients

Clinical course is indistinguishable from idiopathic acute respiratory distress syndrome (ARDS)

Radiograph shows diffuse bilateral airspace consolidation

High-resolution CT scan shows areas of ground-glass attenuation

Biopsy resembles the organizing phase of diffuse alveolar damage, with fibrosis and minimal collagen deposition

Pathologically similar to usual interstitial pneumonia but more homogeneous, and honeycombing is typically absent

Supportive care including mechanical ventilation is critical

Nintedanib and pirfenidone reduce rate of decline in lung function

50–90% of patients die within 2 months

Course is not progressive if patient survives

Lung function may be permanently impaired in survivors