The most likely cause of bihilar lymphadenopathy is

Sarcoidosis Chronic multisystem disorder of unknown cause characterized by accumulation of TH 1 lymphocytes and mononuclear phagocyte in various tissuesof body.Non-caseating sarcoid Granuloma in affected organsLungs (90%)Lymph nodesSkinOthersInterstitial lung disease (fibrosis of lung parenchyma)Pleura is involved, in 1-5% cases unilateral pleural effusion Cavitation is rare B/L hilar lymphadenopathy is the hallmark of Sarcoidosis B/L parotid enlargement Erythema nodosum Lupus pernio (purple blue shiny swollen lesion on nose, cheeks, lips, ears)UveitisRenal hypercalcemia with or without hypercalciuriaAhritisPeripheral neuropathyCor-pulmonale(Refer: Harrison's Principles of Internal Medicine, 18th edition, pg no: 2805-2813)