## Why Sarcoidosis with bilateral hilar lymphadenopathy is right Sarcoidosis classically presents with bilateral hilar lymphadenopathy (BHL) and a "bat wing" appearance on PA chest X-ray. The normal anatomical relationship shown at structure **C** (right hilum lower than left) is preserved in sarcoidosis, but the hila are symmetrically enlarged due to granulomatous inflammation. This is the most common radiological presentation of pulmonary sarcoidosis in Indian patients, particularly affecting young to middle-aged adults. The combination of BHL with clear lung fields and systemic symptoms (ankle edema suggesting erythema nodosum) is pathognomonic for sarcoidosis (Sutton Radiology; Harrison 21e). ## Why each distractor is wrong - **Unilateral bronchogenic carcinoma with metastatic spread**: Bronchogenic carcinoma typically presents as a UNILATERAL hilar mass, not symmetric bilateral enlargement. The "bat wing" pattern is not characteristic of lung cancer. - **Pulmonary tuberculosis with cavitary disease**: TB commonly shows upper lobe cavitary disease with unilateral or asymmetric hilar involvement, not the symmetric bilateral hilar enlargement with clear lung fields seen here. TB also typically shows parenchymal opacification. - **Pneumoconiosis with upper lobe predominance**: Pneumoconiosis (silicosis, asbestosis) presents with upper lobe nodular or reticular opacities and progressive fibrosis, not the acute bilateral symmetric hilar enlargement pattern typical of sarcoidosis. **High-Yield:** "BAT WING" + bilateral hilar enlargement = sarcoidosis until proven otherwise; right hilum is normally lower than left due to left pulmonary artery arching over left main bronchus. [cite: Sutton Radiology; Harrison 21e]
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