Pulmonary sarcoidosis: population differences and pathophysiology.

Sarcoidosis is characterized as a hyperimmune response to an unknown agent(s) at the lesion sites. Regarding pulmonary lesions, macrophage-T lymphocyte alveolitis precedes an epithelioid cell granuloma formation. In the 35 years since the first International Conference on Sarcoidosis, the definition of sarcoidosis has been revised several times, and many new pathophysiologic mechanisms have been proposed. In this review, we focused on four important issues: (1) possible population differences, (2) possible causative agent(s) and the current problems of disease susceptibility or resistance, (3) recent data on pathogenesis (including a genetic approach) and pathophysiologic processes, and (4) monitoring of disease activity.