Lymph Nodes and Lymphatic Drainage

Pulmonary lymphatic vessels may thus be classified into
- Drains along the veins
- Superficial system
  - pleural
  - interlobular (in interlobular septa) and ,
    - drains centrally along the veins to the hilum
  - intralobular
    - some of the drainage of the interstitium of the secondary lobule
- Deeper System
  - intralobular.
    - around
      - bronchovascular bundle
      - perivascular (associated with a blood vessel),
      - peribronchiolar ( least prominent),
      - interalveolar (in interalveolar septa)
    - drains centrally along the bronchovascular bundle
    - join the broncho-mediastinal trunks

The final common pathway for all the lymphatic is via the thoracic duct which enters the left subclavian vein.

The Superficial and Deep Lymphatic Systems at the Secondary Lobular Level

Secondary Lung Lobule
Normal lung histology
This image is a panoramic view of the lung showing secondary lobules and interlobular septa. Within the interalveolar septae, one sees small venules and lymphatics.Courtesy Armando Fraire MD. 32649b
code lung pulmonary alveoli alveolus secondary lobule interlobular septa vein lymphatic histology
interstitium interstitial
32649b

**Secondary Lobule – Lymphatics and Venules Travelling Together**
The arteries and airways pair up and travel together from the interlobular septa to the hilum. The pulmonary lobule, also called the secondary lobule is a structural unit surrounded by a membrane of connective tissue, and it is smaller than a subsegment of lung but larger than an acinus. This diagram shows two secondary lobules lying side by side. The pulmonary arteriole (royal blue) and bronchiole (pink) are shown together in the centre of the lobule (“centrilobular”), while the oxygenated pulmonary venules (red) and lymphatics (yellow) are peripheral and also form a formidable and almost inseparable pair.
42440b03
Davidoff Art Courtesy Ashley Davidoff MD

Difference Between the Upper Lobes and Lower Lobes

The lymphatic drainage of the upper lobes and lower lobes of the lungs differs
- In the upper lobes
  - lymphatic drainage is more extensive and interconnected
  - because the
    - upper lobes contain a
      - larger number of lymph nodes
      - lymphatic vessels in the upper lobes also tend to be
        
        larger and
        
        more numerous and therefore
        
        more efficient circulation of lymphatic fluid.
      - the lower lobes of the lungs
        
        limited lymphatic drainage system,
        
        fewer lymph nodes and
        
        smaller lymphatic vessels.

Lymph Nodes on the Fissures

Lymph nodes om the lung fissures
Ashley Davidoff MD TheCommonVein.net

Heart Failure Kerley B lines
In these images. and c are normal and b and d represent thickened interlobular septa in a patient with congestive heart failure. These are the well known Kerley lines, often spoken about but rarely seen. They are identified as thin horizontal lines usually seen in the costophrenic angles, not being longer than 2 cms in length and touching the pleural surface.
Ashley Davidoff MD TheCommonVein.net
42545c01

Heart Failure with Lymphatic Congestion Kerley A, B , C lines
There is severe congestive cardiac failure in this CXR with evidence of Kerley B lines seen as horizontal thin lines touching the pleura in the right costophrenic angle in a, and the presence of 3 thin lines coursing obliquely toward the hilum in image b, representing distended lymphatics running with the bronchovascular bundles. These lines are called Kerley A lines and they are quite rare. Kerley C lines represent the reticular pattern of intraparenchymal lymphatics which in this case are quite vague.
46424c01
Ashley Davidoff MD TheCommonVein.net

Heart Failure with Lymphatic Congestion with thickening of the Interlobular Septa
Keywords
heart cardiac chest fx pulmonary congestion interstitial edema enlarged pulmonary arteries pulmonary arteriole to bronchiole ratio increased cardiomegaly fx enlarged Kerley B line thickened interlobular septa dx congestive heart failure CHF cardiac failure CTscan CXR plain film Davidoff MD 46425 46427 46428 46432c01 46431 46432 46432c0146424c01
Ashley Davidoff MD TheCommonVein.net

Patient with sarcoidosis showing nodules along the chains of lymphatic distribution including the pleura, and fissures
keywords lung pleura fissures lymphatics interstitium interstitial disease fx nodules dx sarcoidosis CTscan 446843c01 6842 46843 46843c01 46846 46847 46848 46849 46851
Ashley Davidoff MD TheCommonVein.net

Halo Sign Around a Malignant Mass and
Lymphangitis Carcinomatosis

Halo Sign Around a Malignant Mass
CT in the axial plane demonstrates a large, spiculated mass in the right upper lobe with surrounding halo likely reflecting hemorrhage or lymphatic edema around the mass. In addition, there is evidence of irregular interlobular septal thickening likely reflecting lymphatic invasion and indicating lymphangitis carcinomatosa. There is irregular thickening of the major fissure suggesting involvement.
Ashley Davidoff MD TheCommonVein.net 135865

Lymph Nodes

Most of the visible lymph nodes are within the hila and mediastinum. However there are lymph nodes that lie close to the periphery of the lung. These are relatively small measuring approximately 2mm. in diameter. They become larger towards the hila, reaching diameters of between 5 to 10mm.

The mediastinal nodes have been divided into 4 main groups; the superior mediastinal, aortic, inferior mediastinal, and N node are the designated groups. Within these groups there are 14 nodal stations. These 14 stations have been given both names and numbers to aid in the classification and staging of disease.

Lymph Nodes of the Chest
There are Aortic Nodes 5 Subaortic Nodes (A-P window) 6 Paraaortic Nodes (Ascending Aorta or Phrenic) Inferior Mediastinal Nodes 7= subcarinal nodes 8=Paraesophageal Nodes 9 = Pulmonary Ligament Nodes 10 Hilar Nodes 11 Interlobar Nodes 12 Lobar Nodes
Ashley Davidoff
TheCommonVein.net
32682n04.801

Group 3 called “prevascular and retrotracheal nodes” can only be appreciated on the axial images since they are found relatively anterior and posteriorly in the chest.

Superior Mediastinal Nodes

1 Highest Mediastinal Nodes

2 Upper Tracheal Nodes

3 Prevascular and Retrotracheal Nodes

4 Lower Paratracheal Nodes

Superior Mediastinal Nodes
1= Highest, 2= Upper Tracheal and 4 = Lower Paratracheal
32682n01n.800 nodes 1,2,4 Superior mediastinal Nodes 1 Highest Mediastinal Nodes 2 Upper Tracheal Nodes 3 Prevascular and Retrotracheal Nodes 4 Lower Paratracheal Nodes chest mediastinum lymph nodes normal anatomy CTscan Ashley Davidoff MD TheCommonVein.net

Superior Mediastinal Nodes
3 = Prevascular Nodes
This patient has lymphoma and the nodal groups of the mediastinum are all enlarged.
42058c01b
Ashley Davidoff MD TheCommonVein.net

Aortic Nodes

5 Subaortic Nodes (A-P window)

6 Paraaortic Nodes (Ascending Aorta or Phrenic)

Aortic Nodes
5= A-P window and 6= Paraaortic
32682n07n.800 Ashley Davidoff MD TheCommonVein.net

Aortic Nodes
6= paraaortic
Superior Mediastinal
3 – Prevascular Nodes 4 = Lower Paratracheal
42059c01 Ashley Davidoff MD TheCommonVein.net

Inferior Mediastinal Nodes

7 Subcarinal Nodes

8 Paraesophageal Nodes

9 Pulmonary Ligament Nodes

Inferior Mediastinal Nodes
7= Subcarinal, 8= Paraesophageal and 9= Pulmonary Ligament
32682n06n.800 Ashley Davidoff MD TheCommonVein.net

10 Hilar Nodes

11 Interlobar Nodes

12 Lobar Nodes

13 Segmental Nodes

14 Subsegmental Nodes

N Nodes
10=Hilar, 11=”Interlobar,” 12=”Lobar,” 13=”Segmental,” 14 = Subsegmental
32682n05ns.800 Ashley Davidoff MD TheCommonVein.net

Mediastinal Hilar and Intraparenchymal Disease in Sarcoidosis
Patient with sarcoidosis showing mediastinal lymphadenopathy in the aortic nodes paraaortic 6, A-P window 5, Inferior mediastinal subcarinal 7, N Nodes hilum 10, interlobar 11, segmental 13 n Ashley Davidoff MD TheCommonVein.net 46851c01

A Patient with Sarcoidosis with Calcified Nodes at Many Stations

50-year-old male presents with history of Stage 4 sarcoidosis acute chest pain and dyspnea
The initial CXR shows a left sided pneumothorax, diffuse nodular pattern with confluent perihilar infiltrates and a left pleural effusion
A chest tube was placed and a chest CT showed confluent fibrotic masses in the hilar regions totally surrounding the bronchovascular bundles with encasement of the middle lobe artery. In addition, multiple lympho-vascular micronodules are demonstrated. The pulmonary artery measures 32.7mm indicating pulmonary hypertension.
A CXR during this admission shows re-expansion of the pneumothorax. Left lung volume is reduced.
The patient presents 2 years later, again with progressive dyspnea and chest pain and CT PA shows encasement of the airways, right middle lobe pulmonary artery and left lower pulmonary vein by the fibrotic broncho vascular masses, and non-occlusive, subacute pulmonary embolus of the LPA. There are moderate bilateral pleural effusions, calcified lymph nodes, with ongoing pulmonary hypertension with right ventricular enlargement, right atrial enlargement, tricuspid regurgitation and pulmonary hypertension. At this time the patient is intubated.
He again presents 1 month after with chest pain and dyspnea. At this time, he has a tracheostomy. The scout frontal view shows persistent encasement of the left upper lobe bronchus and significant reduction on the volume of the left lung with elevated left hemidiaphragm.
CT PA has similar findings with a large right pleural effusion and unresolved large non occlusive thrombus in the left pulmonary artery.

CALCIFIED LYMPH NODES, RIGHT EFFUSION
SARCOIDOSIS, STAGE IV, PTX, ENCASEMENT
Ashley Davidoff MD

SARCOIDOSIS, STAGE IV, PTX, ENCASEMENT
Ashley Davidoff MD

CALCIFIED LYMPH NODES, RIGHT EFFUSION
Ashley Davidoff MD

CALCIFIED LYMPH NODES, LEFT EFFUSION
SARCOIDOSIS, STAGE IV, PTX, ENCASEMENT
Ashley Davidoff MD

CALCIFIED LYMPH NODES, LEFT EFFUSION
Ashley Davidoff MD

CALCIFIED LYMPH NODES, COMPRESSION LUL BRONCHUS, LEFT EFFUSION
Ashley Davidoff MD

See Radiographics

Applied Anatomy

Knowledge of the anatomy of the secondary lobule is key to the understanding of the subpleural lymphatic system since the lymphatic of this region run in the interlobular septa. The anatomy of the secondary lobule was extensively discussed in part 1 of the lung module. The ability to image the secondary lobule is key to the diagnosis of many of the interstitial lung diseases and it requires high resolution imaging to enable distinction between changes in the interlobular septa changes within the central bronchovascular bundle and changes within the lobule itself. Since the subpleural lymphatics run in the interlobular septa, it becomes our focus when lymphatic disease is evaluated.

Certain diseases have a predilection for the lymphatic system at the subpleural level including sarcoidosis. On the other hand diseases such as lung carcinoma have a predilection for the deep and central nodal system. Since the systems do connect and are both usually involved i is imperative to evaluate both systems.

Subpleural System

The polygonal shape of the secondary lobule is a key shape to recognise. These lobules are well formed at the lung apices, lung bases and particularly at the periphery of the lung. The septa are not usually appreciated in healthy lungs, but may be seen in only mildly diseased lungs as well as advanced disease in the lung. Their presence does not necessarily indicate lymphatic disease since the connective tissue of the septa, and the venules are also located within them.

The polygonal shape of the secondary lobule can be seen all around you when you start looking
This is a series of images demonstrating the shape of the secondary lobule. The first image (1) is a post mortem specimen with congested lungs showing the interlobular septa, while the next (2), is an overlay of the septa in white showing their polygonal shape. The next drawing reveals side-by-side secondary lobules with central bronchovascular bundles and peripheral lympho-vascular bundles. Image 4 is a CT image through the apex of the lung showing thickened secondary lobules in a patient with mild emphysema, and 5 shows marked thickening of the interlobular septa in a patient with end stage sarcoidosis. 6,7,8 show the shape of the secondary lobules in the skin of a giraffe, the bark of a pine, and the ripples of the water respectively.
Ashley Davidoff MD TheCommonVein.net 31866collageSarcoid disease and sarcoid nodules specifically, seek out the lymphatics of both the subleral and the deep systems. Thus when nodules or focal changes are identified on the pleural surfaces, including the fissures, interlobular septa, and bronchovascular bundles then sarcoidosis is a prime suspect. Pleural effusions on the other hand are distinctly uncommon in sarcoidosis.(1-4%). In lymphangitic spread of disease, malignant cells get bundled in to the lymphatics causing obstruction and reducing pulmonary capacity. Thickening of the interlobular septa is a characteristic finding in these cases. In anthracosis, lymph nodes and lymphatics get filled with carbon colored soot.

Anthracotic Lung
Anthracosis – Note the accumulation of carbon particles within the lymphatics along the interlobular septa, outlining the secondary lobules. The carbon particles are inhaled from an anthracotic urban environment. Courtesy Ashley Davidoff MD. 32291 code lung interlobular septum septa secondary lobule pulmonary lobule interstitium interstitial gross pathology carbon

This histological section is from a patient with protate cancer metastatic to the lymphatics of the lungs – lymphangitis obliterans. The first image shows thickened lymphatics which run in the interlobular septa, overlaid in green in (2). Images 3, and 4 are higher power showing clusters of glandular metatstatic deposits.
Ashley Davidoff MD
TheCommonVein.net
32226c1
keywords
lungs pulmonary neoplasm primary prostate lymphatics distended metastases lymphangitis histopathology

Sarcoidosis – thickened lymphatics of the interlobular septa
This cross sectional series of 3 CT images shows end stage sarcoidosis characterised by marked thickening along the lymphovascular bundles. The first image in the upper left shows marked thickening of the interlobular septa caused by granulomatous changes along the lymphatics. Courtesy Priscilla Slanetz MD. 31866c

The Deep System

The subpleural and deep system have a final common pathway. The image below shows this connection by demonstrating spread of malignant disease in the interlobular septa, around the bronchi and in an intrapulmonary lymph node.

This is a post mortem specimen of a lung with lymphangitic spread of prostate carcinoma. Malignant disease is overlaid in green. Note the rounded mass of lymphadenopathy with linear extensions along the thickened bronchovascular bundles. The fine linear bands peripherally are lymphatics congested with tumor.
Ashley Davidoff MD
TheCommonVein.net
32199cw
keywords
lungs pulmonary parenchymal mass neoplasm primary lymphatics distended metastases lymphangitis gross pathology

Calcified intraparenchymal lymph node
This patient with Stage III sarcoidosis has a calcified intraparenchymal node in the confluent fibrosis on the right.
Ashley Davidoff MD TheCommonVein.net 32001

Mediastinal Nodes

Size of Nodes

In general , although we often measure the size, and specifically the short axis of the nodes to determine the presence of disease, we understand that this is a fairly inaccurate method with low specificity . A short axis of more than 10mm implies a pathologically involved node. Often the large node may be reactive and may not contain malignant disease. PET scanning has been an important advance to aid in the distinction between reactive and malignant lymphadenopathy.

This set of images shows pathologically sized mediastinal nodes, and right hilar nodes. The patient would be stage II and operable in the setting of ipsilateral primary lung carcinoma, if these were the only nodes identified and the lesion was 2cms or more away from the carina.
Courtesy Ashley Davidoff MD TheCommonVein.net 31646c

Large Reactive Node – Pathology negative
The node in the azygos region is pathologically enlarged but at pathology was shown to be reactive. note the subtle deformity of the azygos region on the CXR
33082c02 Courtesy Ashley Davidoff MD TheCommonVein.net