Bat wing appearance

Bat wing appearance is a radiologic sign referring to bilateral perihilar lung shadowing seen in frontal chest X-ray and in chest CT.^[1][2] The most common reason for bat wing appearance is the accumulation of oedema fluid in the lungs.^[3] The batwing sign is symmetrical, usually showing ground glass appearance and spares the lung cortices.^[4] This sign is seen in individuals with pneumonia, inhalation injuries, pulmonary haemorrhage, sarcoidosis, bronchoalveolar carcinoma and pulmonary alveolar proteinosis.^[4]