This document discusses unilateral and bilateral hilar enlargement as seen on chest x-rays. It provides details on normal hilar anatomy and signs that suggest pathological processes. Unilateral hilar enlargement can be caused by conditions like tuberculosis, malignancy, or sarcoidosis. Bilateral hilar enlargement may be seen in sarcoidosis, various infections like tuberculosis, or malignancies such as lymphoma. Specific radiological signs described include dense hila, hilar overlay and convergence, and loss of the normal hilar angle, which can help identify hilar masses.

1. Unilateral and
bilateral Hilar
enlargement
BY DR BHARAT SHENBAGARAJ
POST GRADUATE, RESPIRATORY MEDICINE.
SRM MEDICAL COLLEGE, CHENNAI

2.  Hilum is the most difficult part to interpret in a chest X-ray (CXR).
 Anatomically hila are composed of pulmonary arteries and veins, major
bronchi, and lymph nodes.
 Normally bronchi and lymph nodes do not cast any radiological shadow
and pulmonary arteries make up most of the radiographic density of the
hila with superior pulmonary veins make a smaller contribution.
 Whereas, the inferior pulmonary veins enter the left atrium inferior to the
hilum and make no contribution to hilar density

3.  Though both hila should be equal in size and density, we do not get
identical hila in majority of CXRs.
 Unequal hilum may be falsely produced by patient rotation that may result
in distortion of thoracic anatomy in CXR.
 Normally the distances between the medial ends of clavicles from the
spinous process of the vertebral body are equal, and that become unequal
in rotational malpositioning of patient.
 When the pseudoinequality of hilum caused by malpositioning is excluded,
we should proceed for further investigation.

4. Radiological Signs
 Dense Hilum’ sign: Most common presentation of a hilar mass is increased
density over hilum. The dense hilum sign suggests a pathological process
at the hilum: Hilar malignancy or bronchogenic carcinoma should be
suspected.
 In absence of calcification or adenopathy, the hila should appear of equal
density and be symmetric. Identification of increased density is made by
comparing with the opposite side.

5. Hilum Overlay sign:
 A silhouette sign of the hila is called the “hilum overlay sign”.
 If hilar vessels can clearly be seen inside the lesion, the lesion is either
anterior or posterior to the hilum.
 If the hilar vessels cannot be discriminated from the lesion, the lesion is at
the hilum. This is useful for differentiating true hilar mass from
superimposed pulmonary opacities.

6. Hilar convergence sign:
 To distinguish between a prominent hilum and a enlarged pulmonary
artery.
 Pulmonary vessels can be seen to converge and join a dilated pulmonary
artery.
 If branches of pulmonary artery converge towards central mass it is an
enlarged pulmonary artery rather than mass or lymph node in the hilum

7.  Hilar angle: Hilar angle is the angle made between superior pulmonary
vein and intralobar pulmonary artery. It is normally greater than 90°
(concave).
 Loss of concavity will help in identifying hilar mass. Estimation of hilar
angle will also help in identification of hilar mass.

8. Unilateral hilar enlargement
 Tuberculosis
 Malignancy
 Silicosis
 Sarcoidosis
 Non hodgkin’s lymphoma
 Histoplasmosis ( lymphadenopathy with calcification )
 Non- tuberculous mycobacteria
 Pulmonary embolism ( Fleischner sign )
 Pulmonary stenosis ( left hila )

12. Bilateral hilar enlargement
 Expiratory film
 Sarcoidosis
 Infections:
Tuberculosis
Mycoplasma
Infectious mononucleosis
Histoplasmosis
Coccidiomycosis
 Malignancy:
Lymphoma
Bronchogenic & mediastinal tumours

13.  Inorganic dust disease:
Silicosis
Berylliosis
 Hypersensitivity pneumonitis ( Bird fancier’s lung )
 Rule out HIV
 Churg – Strauss syndrome ( EGPA )
 Secondary to heart disease:
Congenital left to right shunts
Cor pulmonale
LVF or Mitral valve disease.

19. THANK
YOU