The most likely cause of bihilar lymphadenopathy
Sarcoidosis is a multi system granulomatous disorder of unknown etiology characterised by the presence of non-caseating granulomas.The definitive feature of Sarcoidosis in a chest X ray is bilateral hilar lymphadenopathy.Lofgren's syndrome is an acute illness characterised by erythema nodosum,peripheral ahropathy,uveitis,bilateral hilar lymphadenopathy,lethargy and occasionally fever. Reference:Davidson' s Medicine-22 nd edition,page no:710 & Harrison
Histoplasmosis
Tuberculosis
Sarcoidosis
Aspergillosis
Respiratory system