PICTORIAL REVIEW
CT of thoracic lymph nodes. Part II: diseases and pitfalls
1T SUWATANAPONGCHED, MD and 2D S GIERADA, MD
1Department of Radiology, Ramathibodi Hospital, Faculty of Medicine, Mahidol University, 270 Rama VI Road, Rajathevi,
Bangkok 10400, Thailand and 2Mallinckrodt Institute of Radiology, Washington University School of Medicine, 510 South
Kingshighway Blvd., Campus Box 8131, Saint Louis, Missouri 63110, USA
ABSTRACT. CT is the primary non-invasive technique for the diagnostic evaluation of
thoracic lymph nodes. The CT patterns and anatomic location of thoracic lymph node
involvement can provide important clues in the diagnosis of many diseases. Part I of the
pictorial review illustrates the anatomic location and drainage of thoracic lymph nodes
in the chest wall, mediastinum, and lungs through examples of pathologic
involvement. Part II of the pictorial review focuses on CT patterns of lymph node
involvement in various pulmonary and extrapulmonary diseases, differential diagnoses
based on CT findings, and pitfalls.
Received 11 April 2005
Revised 23 June 2005
Accepted 11 July 2005
DOI: 10.1259/bjr/82484604
’ 2006 The British Institute of
Radiology
Part II of this pictorial review focuses on diseases
involving thoracic lymph nodes, differential diagnoses
based on CT findings and findings that can mimic
thoracic lymphadenopathy.
Lung cancer
For staging and reporting, lymph node stations are
classified as defined by the American Joint Committee on
Cancer and the Union Internationale Contre le Cancer
(see Figure 1 in Part I) [1]. With size greater than 10 mm,
the conventional criterion, the sensitivity (49–66%) and
specificity (77–86%) of CT for lymph node metastases is
limited [2]. Diagnostic accuracy may be improved using
positron emission tomography (PET), or integrated PET-
CT scanning [2]. Due to poor survival, surgery for lung
cancer is generally contraindicated when mediastinal
lymph nodes are involved. Some surgeons perform pre-
operative sampling of mediastinal nodes in all patients,
while others limit pre-operative sampling to those with
enlarged nodes on CT or positive PET scans.
Lymphoma
Mediastinal lymph node involvement is more frequent
than hilar, which is usually asymmetric and accompa-
nied by mediastinal involvement [3]. Lymphoma tends
to expand along or around rather than invade existing
structures (Figure 1). In Hodgkin’s disease, upwards of
85% of patients have intrathoracic involvement on CT,
compared with approximately 50% with non-
Hodgkin’s lymphoma [3, 4]. Hodgkin’s disease tends to
spread contiguously between lymph node groups, while
non-Hodgkin’s lymphoma more frequently involves
atypical lymph node sites, such as posterior mediastinal
and anterior diaphragmatic nodes (Figures 5 and 6 in
Part I) [3, 4].
Metastases
In addition to lung cancer, malignancies that may
metastasise to thoracic lymph nodes include breast
(Figure 4 in Part I), melanoma, head and neck, genitour-
inary (Figures 7 and 9 in Part I), and gastrointestinal
Address correspondence to: D S Gierada, 510 S. Kingshighway
Blvd., St. Louis, MO 63105, USA. E-mail: gieradad@wustl.edu
Figure 1. Enhanced CT scan in a 37-year-old woman with
lymphoma demonstrating enlarged pre-vascular (arrow-
heads) and left upper paratracheal (arrow) nodes, encasing
the patent left carotid (C) and left subclavian (S) arteries.
Lack of vessel invasion or constriction is a feature that may
be helpful for distinguishing lymphoma from metastatic
carcinoma. (From Glazer HS, Semenkovich JW, Gutierrez FR.
Mediastinum. In: Lee JKT, Sagel SS, Stanley RJ, Heiken JP,
editors. Computed body tomography with MRI correlation,
3rd edn. Philadelphia, PA: Lippincott-Raven Publishers,
1998:261–349 [13]. Reprinted with permission).
The British Journal of Radiology, 79 (2006), 999–1006
The British Journal of Radiology, December 2006 999
carcinomas including oesophageal carcinoma (Figure 8
in Part I) and melanoma [5]. Lymph node involvement is
usually asymmetric [5].
Sarcoidosis
In sarcoidosis (Figure 2), CT commonly reveals invol-
vement of the lower paratracheal, aortopulmonary
window, subcarinal, and bilateral hilar and interlobar
nodal stations, slightly more frequently on the right [6].
Unilateral hilar disease, mediastinal lymphadenopathy
without hilar disease and posterior mediastinal adeno-
pathy are rarely seen with sarcoidosis, and are more
suggestive of lymphoma, metastatic cancer, or granulo-
matous infection. Lymph node calcification (occasionally
eggshell pattern) can be seen in up to 25% of cases,
usually in long-standing disease [6].
(a) (b)
Figure 2. A 37-year-old woman with sarcoidosis. (a) Enhanced CT scan at level of aortic arch reveals enlarged para-aortic nodes
(straight arrows) lying anterior and lateral to the aortic arch at the levels below the superior margin of the aortic arch (A);
enlarged right lower paratracheal nodes (open arrows); and enlarged retrotracheal node (wavy arrow). Note mild contrast
enhancement of these enlarged lymph nodes. V 5 left brachiocephalic vein, Oe 5 oesophagus. (b) Enhanced CT scan at the
subcarinal level reveals enlarged bilateral interlobar nodes (open arrows) and subcarinal nodes (closed arrow). As with
lymphoma, obstruction of mediastinal or hilar vessels or bronchi is rare, even with marked lymph node enlargement. A 5
ascending aorta, D 5 descending aorta.
Figure 3. Enhanced CT scan in a 58-year-old man with
histoplasmosis revealing enlarged subaortic (arrow) and left
lower paratracheal (arrowhead) nodes, secondary to left
upper lobe histoplasmosis pneumonia (open arrows).
Figure 4. Enhanced CT scan with lung-window setting in a
48-year-old woman with haemoptysis showing calcified left
hilar node (arrow) eroded into the left main bronchus,
consistent with broncholithiasis. Multiple calcified subcarinal
and left hilar nodes (arrowheads) are seen, characteristic of
prior granulomatous infection.
T Suwatanapongched and D S Gierada
1000 The British Journal of Radiology, December 2006
Infectious granulomatous disease
Primary tuberculosis and histoplasmosis (Figure 3)
may produce low attenuation lymphadenopathy,
sometimes with rim enhancement, which suggests active
disease [7]. Lymph node calcification resulting from
these infections may be seen on chest CT studies
performed for other indications. CT is useful in
diagnosing complications from granulomatous infec-
tions, such as broncholithiasis (Figure 4), middle lobe
syndrome and fibrosing mediastinitis. Rare infections
associated with hilar or mediastinal lymphadenopathy
include tularaemia, plague and anthrax, the latter of
which has been found to have high attenuation adeno-
pathy, possibly due to haemorrhage [8].
Thoracic lymphadenopathy in AIDS
Mediastinal lymph node enlargement (short axis .
10 mm) is seen in approximately 35–40% of HIV-infected
patients and raises concern for infection or malignancy
[9]. Tuberculous and non-tuberculous mycobacterial
disease and bacterial pneumonia are the primary
infectious causes, while lymphoma and Kaposi’s sar-
coma are the major neoplastic causes [9].
Lymphadenopathy without parenchymal lung disease
may occur with tuberculosis, Mycobacterium Avium-
Complex (Figure 5) and cryptococcal infection [10].
Lymphadenopathy is not a typical feature of
Pneumocystis carinii infection, but widespread lymph
node calcification with a characteristic cloud-like or
foamy appearance has been described [11].
Figure 5. Enhanced CT scan in a 43-year-old man with AIDS
and Mycobacterium Avium-Complex infection revealing
slightly low attenuation subcarinal (black arrowheads) and
right hilar (white arrow) lymphadenopathy. There was no
visible lung disease.
(a) (b)
Figure 6. (a, b) Enhanced CT scans in a 64-year-old woman with hyaline-vascular type of Castleman’s disease demonstrating (a)
enhancing para-aortic (arrows), (b) subaortic (arrowhead), (a,b) right paratracheal (curved arrow), and (b) left hilar (open arrow)
nodes, separated from subaortic nodes by the first branch of the left pulmonary artery (wavy arrow). The hyaline-vascular type is
most common, and usually presents as an asymptomatic, solitary lymph node mass in the middle or posterior mediastinum or
hilum. The less common plasma-cell type is usually associated with systemic symptoms and disseminated disease.
Pictorial review: CT of thoracic lymph nodes
The British Journal of Radiology, December 2006 1001
Castleman’s disease
Castleman’s disease (Figure 6) is a type of lymph node
hyperplasia of unknown aetiology with female prepon-
derance. Because the lesions are highly vascular, contrast
enhancement is almost invariable. Calcification may be
seen [12].
Chronic infiltrative lung disease
Presumably related to chronic inflammation, mild
mediastinal and hilar lymphadenopathy (short axis
>1.0 cm, usually , 1.5 cm) may be seen in idiopathic
pulmonary fibrosis (Figure 7), collagen vascular diseases
such as rheumatoid arthritis and scleroderma, extrinsic
allergic alveolitis, cryptogenic organizing pneumonia,
and some inhalational lung diseases such as silicosis and
asbestosis [13, 14]. Lymph nodes in patients with silicosis
are frequently calcified, often in an eggshell pattern
(Figure 8).
(a) (b)
Figure 7. A 64-year-old man with idiopathic pulmonary fibrosis (a) Enhanced CT scan shows mild para-aortic (arrow), subaortic
(arrowheads) and right hilar (open arrow) lymphadenopathy. (b) Lung-window setting at the corresponding level shows
peripheral, subpleural reticular opacities, characteristic of idiopathic pulmonary fibrosis. (From Sagel SS, Slone RM. Lung. In Lee
JKT, Sagel SS, Stanley RJ, Heiken JP, editors. Computed body tomography with MRI correlation, 3rd edn. Philadelphia, PA:
Lippincott-Raven Publishers, 1998:351–454 [15]. Reprinted with permission).
Figure 8. Enhanced CT scan in a 38-year-old man with
silicosis showing enlarged right and left lower paratracheal
(arrows), subaortic (open arrows), and para-aortic (thin
arrow) nodes with eggshell calcification. Note calcified
bilateral intrapulmonary nodes (arrowheads). A 5 ascending
aorta, D 5 descending aorta, V 5 superior vena cava.
Figure 9. Non-enhanced CT scan in a 41-year-old man with
amyloidosis demonstrating calcified bilateral hilar, subcar-
inal, subaortic, and para-aortic nodes. Although an unusual
cause of mediastinal lymphadenopathy, 75% of patients
with thoracic amyloidosis have mediastinal lymph node
enlargement, which may contain punctate calcification (as
in this case), often associated with pulmonary parenchymal
disease or pleural effusion. A 5 ascending aorta, D 5
descending aorta, S 5 superior vena cava (From Glazer HS,
Molina PL, Siegel MJ, Sagel SS. High-attenuation mediastinal
masses on unenhanced CT. AJR Am J Roentgenol
1991;156:45–50 [16]. Reprinted with permission).
T Suwatanapongched and D S Gierada
1002 The British Journal of Radiology, December 2006
Differential diagnosis of CT findings
Calcified lymph nodes
In addition to old granulomatous disease (Figure 4),
sarcoidosis, silicosis (Figure 8), and Pneumocystis carinii
infection, lymph node calcification may be seen with
certain metastases, such as ovarian (Figures 7 and 9 in
Part I) or colonic adenocarcinoma, osteosarcoma, papil-
lary thyroid carcinoma and bronchogenic carcinoma [13].
Amyloidosis (Figure 9) and healed lymphoma
after radiation therapy are other causes. Uptake of
lymphangiographic contrast in lymph nodes can mimic
calcification.
Enhancing lymph nodes
In addition to Castleman’s disease (Figure 6), marked
lymph node enhancement may occur in hypervascular
metastases from melanoma, renal cell carcinoma, carci-
noid (Figure 11 in Part I), papillary thyroid cancer and
(a) (b)
Figure 11. Arterial phase CT scan (a) in a 50-year-old man with liver cirrhosis demonstrating soft tissue density (arrows, a and b)
surrounding the oesophagus (Oe), seen to represent enhancing tubular structures during the portal venous phase (b),
characteristic of oesophageal varices. A 5 descending aorta, V 5 inferior vena cava, L 5 liver, S 5 stomach.
(a) (b)
Figure 10. Aberrant right subclavian artery in a 75 year-old woman with gastric cancer. (a) Non-enhanced CT scan at the level of
the left brachiocephalic vein (V) shows a well-defined, soft tissue nodule (arrow) lying to the right of the oesophagus (*),
mimicking an enlarged lymph node. Note relatively smaller brachiocephalic artery (a) than usual. T 5 trachea. (b) Non-enhanced
CT scan at the lower level shows that the nodule is seen to represent an aberrant right subclavian artery (arrows) arising from
the aortic arch (AA). It crosses the mediastinum from left to right behind the oesophagus (*) and trachea (T). S 5 superior vena
cava.
Pictorial review: CT of thoracic lymph nodes
The British Journal of Radiology, December 2006 1003
Figure 12. Enhanced CT scan in a 54-year-old woman with
sickle cell disease showing bilateral paravertebral soft tissue
masses (arrows), consistent with extramedullary haemato-
poiesis. (From Slone RM, Gierada DS. Pleura, chest wall, and
diaphragm. In Lee JKT, Sagel SS, Stanley RJ, Heiken JP,
editors. Computed body tomography with MRI correlation
(3rd edn). Philadelphia, USA: Lippincott-Raven Publishers,
1998:351–454 [17]. Reprinted with permission).
(a) (b)
Figure 13. (a, b) Non-enhanced and enhanced CT scans in a 52-year-old woman showing normal superior pericardial recesses
seen as small, non-enhanced near-water density structures (arrows) posterior to the ascending aorta (AA) and in the groove
between the ascending aorta and pulmonary artery (P). The typical location and CT appearance allow pericardial recesses to be
distinguished from mediastinal lymphadenopathy. Note a normal right lower paratracheal node containing a fat hilum
(arrowhead). DA 5 descending aorta.
Figure 14. Enhanced CT scan in a 71-year-old man with
aortic dissection showing slightly lobulated retrocrural
structure of water attenuation (arrows), consistent with
cisterna chyli.
T Suwatanapongched and D S Gierada
1004 The British Journal of Radiology, December 2006
Kaposi’s sarcoma. Mild enhancement may be seen in
tuberculosis, fungal disease, lymphoma, metastatic lung
cancer and sarcoidosis (Figure 2) [13].
Low-attenuation lymph nodes
Low attenuation lymphadenopathy, which may be a
result of necrosis or cystic degeneration, can be seen in
metastatic carcinoma from the lung, testis, ovary and
lymphoma (Figure 5 in Part I), in infectious disease such
as tuberculous or fungal infections and in Whipple’s
disease [13].
Pitfalls
Anomalous or aberrant mediastinal vessels, such as an
aberrant right subclavian artery (Figure 10), anomalous
left brachiocephalic vein, persistent left superior vena
cava and azygos continuation of the inferior vena cava,
and nodular diaphragmatic crura occasionally imitate
mediastinal lymph node masses. Confusion is avoided
by tracing such structures on contiguous scans, along
with an awareness of such variations, when intravenous
contrast is not administered. Para-oesophageal varices
(Figure 11) and extramedullary haematopoiesis
(Figure 12) can mimic posterior mediastinal adenopathy.
Characteristic low attenuation and lack of intravenous
contrast enhancement help to distinguish fluid in the
pericardial recesses (Figure 13) and mediastinal broncho-
genic cysts from mediastinal lymph nodes. The cisterna
chyli (Figure 14) may mimic low attenuation posterior
diaphragmatic or retrocrural lymphadenopathy.
Lesions that may mimic high attenuation, enhancing
lymphadenopathy include mediastinal paraganglioma,
intrathoracic thyroid (Figure 15), ectopic parathyroid
adenoma (Figure 16) or parathyroid hyperplasia, and
haemangioma [13].
(a)
(c)
(b)
Figure 15. (a–c) Enhanced CT scans in a 70-year-old man with intrathoracic goitre showing a large, inhomogeneously enhancing
left paratracheal mass (arrowheads), displacing the trachea (T) to the right side. The mass is contiguous with the left lobe of the
thyroid gland (th, c) on cephalad scan. Contiguity with the thyroid gland helps to distinguish intrathoracic goiter from
lymphadenopathy.
Pictorial review: CT of thoracic lymph nodes
The British Journal of Radiology, December 2006 1005
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Figure 16. Enhanced CT scan in a 54-year-old woman with
ectopic parathyroid adenoma demonstrating an intensely
enhancing soft tissue mass (arrow) in the aortopulmonary
window region. A5 ascending aorta, D 5 descending aorta,
P 5 pulmonary artery.
T Suwatanapongched and D S Gierada
1006 The British Journal of Radiology, December 2006