Sarcoidosis

Sarcoidosis is a multisystem inflammatory disorder of unknown etiology characterized by non-caseating granuloma formation in affected organs, most commonly the lungs and mediastinal lymph nodes. The disease can affect virtually any organ system including lungs, liver, heart, nervous system, skin, and eyes. The pathophysiology involves aberrant immune response to unknown antigen(s), with enhanced Th17 differentiation and granuloma formation. Clinical presentation is highly variable: many patients present with incidental findings on imaging (bilateral hilar lymphadenopathy), while others present with pulmonary symptoms (cough, dyspnea), systemic symptoms (fever, fatigue, arthralgia), or organ-specific manifestations (cardiac arrhythmias, neurological disease, skin lesions). Approximately one-third of patients have self-limited disease that resolves spontaneously; one-third have persistent disease; and one-third develop progressive organ dysfunction. Diagnosis involves clinical and radiological findings plus histological confirmation of non-caseating granulomas.