Bilateral hilar lymphadenopathy is a bilateral enlargement of the lymph nodes of pulmonary hila. It is a radiographic term for the enlargement of mediastinal lymph nodes and is most commonly identified by a chest x-ray. Bilateral hilar lymphadenopathy is a bilateral enlargement of the lymph nodes of pulmonary hila. It is a radiographic term for the enlargement of mediastinal lymph nodes and is most commonly identified by a chest x-ray. The following are causes of BHL: