Approach to unequal hilum on chest X-ray

Abstract

Hilum is a tricky part in chest X-ray (CXR) for understanding. Anatomically, pulmonary arteries and veins, major bronchi, and lymph nodes with pulmonary arteries contributed most of the radiographic density of the hila with superior pulmonary veins making a smaller contribution. Though both hila should be indistinguishable in size and density, we do not get equal hila in majority of CXRs. Rotational malpositioning must be kept in mind, while interpreting CXRs of unequal hilum. For interpreting hilum, we should search for four factors shape, radiopacity, proportionate size, absolute size, hilar angle, contour of pulmonary artery. There are numerous causes of hilar enlargement. It is the clinical presentation which will help in tapering the differential diagnosis. Asymmetric hilum is a challenging subject for pulmonologists. Interpretation of unequal hilum depends on findings of detail history, meticulous clinical examination, and appropriate investigation.

Keywords

• Approach
• chest X-ray
• hilum
• interpretation
• unequal