Table of ContentsView AllTable of ContentsAnatomyTestsMasses/EnlargementLymphadenopathy
Table of ContentsView All
View All
Table of Contents
Anatomy
Tests
Masses/Enlargement
Lymphadenopathy
The hilum of the lung is the wedge-shaped area on the central portion of each lung, located on themedial (middle) aspect of each lung. The hilar region is where thebronchi, arteries, veins, and nerves enter and exit the lungs.
Enlargement of the hilum may occur due to tumors (such as lung cancer), pulmonary hypertension, or enlarged hilar lymph nodes due to conditions such as infections (especially tuberculosis and fungal infections), cancer (either local or metastatic), sarcoidosis, and more.
This area can be difficult to visualize on a chest X-ray, and further tests such as computed tomography (CT) scan (sometimes requiring contrast dye, but not always) are often needed to determine if a problem exists.
This article will describe the purpose and anatomy of the hilum, discuss the tests used to examine it, and explain what hilar masses or enlarged lymph nodes in this area could mean.
How to Manage Progressive Pulmonary Hypertension
Theresa Chiechi / Verywell
Anatomy of the Hilum
Both the right and the left lung have a hilum which lies roughly midway down the lungs, and slightly towards the back (closer to the vertebrae than to the front of the chest). Each lung may be visualized as having an apex (the top), a base (the bottom), a root, and a hilum.
The major bronchi, pulmonary arteries, pulmonary veins, and nerves are the structures which enter and exit the lungs in this region.Lymph nodes, called hilar lymph nodes, are also present in this region. Both hila are similar in size, with the left hilum usually found slightly higher in the chest than the right hilum.
Tests to Evaluate the Hilum
Abnormalities in the hilum are usually noted on imaging studies, but further tests and procedures are often needed to determine if a problem is present, and where.
Imaging
On a chest X-ray, the hilar region reveals a shadow that consists of the combination of lymph nodes, the pulmonary arteries, and the pulmonary veins.
Due to the overlap of these structures, it can sometimes be difficult to detect enlargement of these lymph nodes or the presence of a mass in this region. This is one of the reasons why ordinarychest X-rays can miss lung cancer.
Chest CT scans (with or without contrast) can lead to better visualization of these structures. Apositron emission tomography (PET) scanis sometimes very helpful if a tumor is suspected.
Radiology Report
When a radiologist views the hilum, they will report on whether there is symmetry between the right and left hilum as well as the following:
Depending on the particular study, the radiologist may note hilar enlargement and if a hilar mass or hilar lymphadenopathy (enlarged hilar lymph nodes) are present.
Procedures
In addition to imaging tests, abnormalities in the hilar region may be identified with tests such as abronchoscopy, a test in which a tube is inserted through the mouth and down into the major airways (bronchi).
An ultrasound done via an ultrasound probe inserted during a bronchoscopy (anendobronchial ultrasound) can sometimes obtain samples of abnormal tissue lying near the major airways.
A test called amediastinoscopy(a surgical procedure in which a surgeon is able to explore the area between the lungs, including the hilar lymph nodes) may be needed to better visualize the region or to obtain a biopsy sample, though PET scanning has replaced the need for this procedure in many cases.
Hilar Masses or Enlargement
Symptoms
Enlargement of the hilum may be noted when imaging studies are done to evaluate symptoms such as a persistent cough, coughing up blood, shortness of breath, or recurrent respiratory infections, or may be found incidentally on a test such as a CT scan. Both masses and enlarged lymph nodes may be due to cancer or benign causes.
What Causes Swollen Lymph Nodes?
Location of Masses or Lymphadenopathy
Some apparent abnormalities of the hilum may simply be due to positioning, and further views may rule out problems. If a mass or enlargement is noted, possible causes can vary depending on the appearance:
Causes
There are four main reasons why the hilum of one or both lungs may appear enlarged on an X-ray. These include:
Hilar Lymph Node Disease
Enlarged lymph nodes in the hilum may occur in both the right and left hilum (bilateral lymphadenopathy) or on one side alone (asymmetric lymphadenopathy.) Causes may include:
Summary
There are a number of conditions that can cause an abnormal appearance of the hilum on imaging studies, many of which are serious.Tumors, both primary and metastatic, can cause both hilar masses and lymphadenopathy. However, the most common causes overall include tuberculosis worldwide, and conditions such as histoplasmosis, coccidioidomycosis, and sarcoidosis in the United States.
If your healthcare provider notes an abnormality on your exam, further testing will be needed. They will also take a careful history looking for any other symptoms suggestive of a tumor, infection, or inflammatory process. Most of the time a biopsy will be needed to obtain a definitive diagnosis.
13 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Sarkar S, Jash D, Maji A, Patra A.Approach to unequal hilum on chest X-ray.J Assoc Chest Physicians. 2013;1(2):32-37. doi:10.4103/2320-8775.123204Del Ciello A, Franchi P, Contegiacomo A, Cicchetti G, Bonomo L, Larici AR.Missed lung cancer: when, where, and why?.Diagn Interv Radiol. 2017;23(2):118‐126. doi:10.5152/dir.2016.16187National Library of Medicine: MedlinePlus.Lung PET scan.Herth, F.Bronchoscopic techniques in diagnosis and staging of lung cancer.Breathe. 2011;7(4):324-337. doi:10.1183/20734735.021510Criado E, Sánchez M, Ramírez J, et al.Pulmonary sarcoidosis: typical and atypical manifestations at high-resolution CT with pathologic correlation.RadioGraphics. 2010;30(6):1567-1586. doi:10.1148/rg.306105512Toma CL, Dumitrache-Rujinski S, Belaconi IN, et al.Unilateral pulmonary hilar tumor mass: is it always lung cancer?Maedica. 2013;8(1):30-3.MacDuff A, Arnold A, Harvey J.Management of spontaneous pneumothorax: British Thoracic Society pleural disease guideline 2010.Thorax. 2010;65(Suppl 2):ii18-ii31. doi:10.1136/thx.2010.136986Solbes E, Harper RW, Louie S.The fear of lymphadenopathy: does it portend sarcoidosis or lymphoma?.Consultant. 2016;56(11):1016-1020.Cong CV, Ly TT, Anh PQ, Duc NM.Primary mediastinal lymph node tuberculosis diagnosed using endobronchial ultrasound-guided transbronchial needle aspiration: literature review and case report.Radiol Case Rep. 2022;17(5):1709-1717. doi:10.1016/j.radcr.2022.02.085Canters for Disease Control and Prevention.About valley fever.Centers for Disease Control and Prevention.About histoplasmosis.Zhao S, Wan Y, Huang Z, Song B, Yu J.Imaging and clinical features of Castleman disease.Cancer Imaging. 2019;19(1):53. doi:10.1186/s40644-019-0238-0Cleveland Clinic.Castleman disease.
13 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Sarkar S, Jash D, Maji A, Patra A.Approach to unequal hilum on chest X-ray.J Assoc Chest Physicians. 2013;1(2):32-37. doi:10.4103/2320-8775.123204Del Ciello A, Franchi P, Contegiacomo A, Cicchetti G, Bonomo L, Larici AR.Missed lung cancer: when, where, and why?.Diagn Interv Radiol. 2017;23(2):118‐126. doi:10.5152/dir.2016.16187National Library of Medicine: MedlinePlus.Lung PET scan.Herth, F.Bronchoscopic techniques in diagnosis and staging of lung cancer.Breathe. 2011;7(4):324-337. doi:10.1183/20734735.021510Criado E, Sánchez M, Ramírez J, et al.Pulmonary sarcoidosis: typical and atypical manifestations at high-resolution CT with pathologic correlation.RadioGraphics. 2010;30(6):1567-1586. doi:10.1148/rg.306105512Toma CL, Dumitrache-Rujinski S, Belaconi IN, et al.Unilateral pulmonary hilar tumor mass: is it always lung cancer?Maedica. 2013;8(1):30-3.MacDuff A, Arnold A, Harvey J.Management of spontaneous pneumothorax: British Thoracic Society pleural disease guideline 2010.Thorax. 2010;65(Suppl 2):ii18-ii31. doi:10.1136/thx.2010.136986Solbes E, Harper RW, Louie S.The fear of lymphadenopathy: does it portend sarcoidosis or lymphoma?.Consultant. 2016;56(11):1016-1020.Cong CV, Ly TT, Anh PQ, Duc NM.Primary mediastinal lymph node tuberculosis diagnosed using endobronchial ultrasound-guided transbronchial needle aspiration: literature review and case report.Radiol Case Rep. 2022;17(5):1709-1717. doi:10.1016/j.radcr.2022.02.085Canters for Disease Control and Prevention.About valley fever.Centers for Disease Control and Prevention.About histoplasmosis.Zhao S, Wan Y, Huang Z, Song B, Yu J.Imaging and clinical features of Castleman disease.Cancer Imaging. 2019;19(1):53. doi:10.1186/s40644-019-0238-0Cleveland Clinic.Castleman disease.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Sarkar S, Jash D, Maji A, Patra A.Approach to unequal hilum on chest X-ray.J Assoc Chest Physicians. 2013;1(2):32-37. doi:10.4103/2320-8775.123204Del Ciello A, Franchi P, Contegiacomo A, Cicchetti G, Bonomo L, Larici AR.Missed lung cancer: when, where, and why?.Diagn Interv Radiol. 2017;23(2):118‐126. doi:10.5152/dir.2016.16187National Library of Medicine: MedlinePlus.Lung PET scan.Herth, F.Bronchoscopic techniques in diagnosis and staging of lung cancer.Breathe. 2011;7(4):324-337. doi:10.1183/20734735.021510Criado E, Sánchez M, Ramírez J, et al.Pulmonary sarcoidosis: typical and atypical manifestations at high-resolution CT with pathologic correlation.RadioGraphics. 2010;30(6):1567-1586. doi:10.1148/rg.306105512Toma CL, Dumitrache-Rujinski S, Belaconi IN, et al.Unilateral pulmonary hilar tumor mass: is it always lung cancer?Maedica. 2013;8(1):30-3.MacDuff A, Arnold A, Harvey J.Management of spontaneous pneumothorax: British Thoracic Society pleural disease guideline 2010.Thorax. 2010;65(Suppl 2):ii18-ii31. doi:10.1136/thx.2010.136986Solbes E, Harper RW, Louie S.The fear of lymphadenopathy: does it portend sarcoidosis or lymphoma?.Consultant. 2016;56(11):1016-1020.Cong CV, Ly TT, Anh PQ, Duc NM.Primary mediastinal lymph node tuberculosis diagnosed using endobronchial ultrasound-guided transbronchial needle aspiration: literature review and case report.Radiol Case Rep. 2022;17(5):1709-1717. doi:10.1016/j.radcr.2022.02.085Canters for Disease Control and Prevention.About valley fever.Centers for Disease Control and Prevention.About histoplasmosis.Zhao S, Wan Y, Huang Z, Song B, Yu J.Imaging and clinical features of Castleman disease.Cancer Imaging. 2019;19(1):53. doi:10.1186/s40644-019-0238-0Cleveland Clinic.Castleman disease.
Sarkar S, Jash D, Maji A, Patra A.Approach to unequal hilum on chest X-ray.J Assoc Chest Physicians. 2013;1(2):32-37. doi:10.4103/2320-8775.123204
Del Ciello A, Franchi P, Contegiacomo A, Cicchetti G, Bonomo L, Larici AR.Missed lung cancer: when, where, and why?.Diagn Interv Radiol. 2017;23(2):118‐126. doi:10.5152/dir.2016.16187
National Library of Medicine: MedlinePlus.Lung PET scan.
Herth, F.Bronchoscopic techniques in diagnosis and staging of lung cancer.Breathe. 2011;7(4):324-337. doi:10.1183/20734735.021510
Criado E, Sánchez M, Ramírez J, et al.Pulmonary sarcoidosis: typical and atypical manifestations at high-resolution CT with pathologic correlation.RadioGraphics. 2010;30(6):1567-1586. doi:10.1148/rg.306105512
Toma CL, Dumitrache-Rujinski S, Belaconi IN, et al.Unilateral pulmonary hilar tumor mass: is it always lung cancer?Maedica. 2013;8(1):30-3.
MacDuff A, Arnold A, Harvey J.Management of spontaneous pneumothorax: British Thoracic Society pleural disease guideline 2010.Thorax. 2010;65(Suppl 2):ii18-ii31. doi:10.1136/thx.2010.136986
Solbes E, Harper RW, Louie S.The fear of lymphadenopathy: does it portend sarcoidosis or lymphoma?.Consultant. 2016;56(11):1016-1020.
Cong CV, Ly TT, Anh PQ, Duc NM.Primary mediastinal lymph node tuberculosis diagnosed using endobronchial ultrasound-guided transbronchial needle aspiration: literature review and case report.Radiol Case Rep. 2022;17(5):1709-1717. doi:10.1016/j.radcr.2022.02.085
Canters for Disease Control and Prevention.About valley fever.
Centers for Disease Control and Prevention.About histoplasmosis.
Zhao S, Wan Y, Huang Z, Song B, Yu J.Imaging and clinical features of Castleman disease.Cancer Imaging. 2019;19(1):53. doi:10.1186/s40644-019-0238-0
Cleveland Clinic.Castleman disease.
Meet Our Medical Expert Board
Share Feedback
Was this page helpful?Thanks for your feedback!What is your feedback?OtherHelpfulReport an ErrorSubmit
Was this page helpful?
Thanks for your feedback!
What is your feedback?OtherHelpfulReport an ErrorSubmit
What is your feedback?
