Mediastinal masses

1. Radio imaging in Mediastinal
masses
By Dr. Pankaj Kaira
JR 1 Radiodiagnosis
SRMSIMS Bareilly

2. Introduction
• Many mediastinal reflections can be appreciated at conventional
radiography (CR), and their presence or distortion is the key to the
interpretation of mediastinal abnormalities .
• However, computed tomography (CT) is the most important
tool in the evaluation of a mediastinal mass. Characterisation on CT
is based on specific attenuation of air, fat, water and calcium .High-
resolution multiplanar reformation images display the detailed
anatomical relationship of the tumour with the adjacent structures.
• An excellent soft tissue contrast also designates magnetic
resonance imaging (MRI) as an ideal tool to evaluate tumours of the
mediastinum. Assessment of preoperative relationships with the
pericardium, heart cavities, spinal cord and vascular involvement is
a common indication.

3. Mediastinal Boundaries
Compartment Anteriorly Posteriorly
Anterior Sternum Anterior aspect of
trachea and posterior
margin of heart
Middle Anterior aspect of
trachea and posterior
margin of heart
A vertical line drawn
along the thoracic
vertebrae 1 cm behind
their anterior margins
Posterior Vertical line drawn
along the thoracic
vertebrae 1 cm behind
their anterior margins
Costovertebral junction
A M P
The Felson method of division is based on findings at
lateral chest radiography

4. Mediastinal Contents
Compartment Main Strictures
Anterior Fat, lymph nodes, thymus, heart, ascending aorta
Middle Trachea, bronchi, lymph nodes, oesophagus, descending
aorta
Posterior Para vertebral soft tissues
Mediastinal
Masses
Compartment % Malignant
Anterosuperior 59
Middle 29
Posterior 16
Mediastinal
division
Most common
tumors
Anterior-
superior
Thymoma
Middle Lymphoma
posterior Neurogenic
tumors

5. Approach
1. Is the mass actually in the mediastinum or is it in
the lung?
2. If in the mediastinum, then in which
compartment?
3. What is the differential diagnosis for the mass?

6. • PA and lateral chest films are the first step in
distinguishing from which mediastinal compartment
the mass is arising from.
• CT & MRI is the next step, better characterizing the
nature and extent of the lesion, thus narrowing the
differential diagnosis.
• Tissue biopsy is required for definitive diagnosis, and
surgical resection for definitive cure.
Investigations

7. Clues to locate mass to mediastinum
Mediastinal masses are
lined by parietal pleura, so
will have:
Masses in the lung
parenchyma typically:
– Smooth contour
– Mediastinal mass will
create obtuse angles
with the lung .
– Not contain air
bronchograms
– May be seen bilaterally
– Mediastinal lines will be
disrupted
– Are surrounded by air
– A lung mass abutts the
mediastinal surface and
creates acute angles
with the lung
– May contain air
bronchograms
– Will be on one side only

8. LEFT: A lung mass abutts the mediastinal surface and creates acute angles with
the lung.
RIGHT: A mediastinal mass will sit under the surface of the mediastinum,
creating obtuse angles with the lung

9. Which compartment?
Many mediastinal reflections can be appreciated at conventional
radiography (CR), and their presence or distortion is the key to the
interpretation of mediastinal abnormalities .
1. Hilum overlay and convergence signs
2. Paratracheal stripe
3. Azygo-oesophageal recess
4. Paraspinal Lines
5. Cervicothoracic sign
6. Thoracoabdominal sign
7. Anterior Junction line
8. Posterior Junction Line
9. Effect on adjacent structures
 Trachea - deviation or narrowing of trachea seen with anterior
compartment masses
 Ribs - bony destruction seen with posterior compartment masses

10. Hilum overlay and convergence signs
• Principle of hilum overlay
▫ The proximal segments of
the R and L main
pulmonary arteries lie
lateral to the cardiac
silhouette on PA film
• An anterior mediastinal mass
will overlap the main
pulmonary arteries, therefore
they will be seen within the
margins of the mass
• Hilum convergence
▫ To distinguish between
enlarged pulmonary
artery and mediastinal
mass
• If branches of the
pulmonary artery converge
toward a central mass -
enlarged PA
• If branches of PA converge
toward the heart rather
than the central mass -
mediastinal tumor

11. Hilum can
be seen
through
mass
This must be an anterior
mediastinal mass because
it overlaps rather than
“pushes out” the main
pulmonary arteries
This particular example is a thymoma

12. Cervicothoracic sign
Described by Felson:
• The anterior mediastinum ends at the level of the clavicles.
• The posterior mediastinum extends much higher.
• Therefore
▫ any mass that remains sharply outlined in the apex of
the thorax must be posterior and entirely within the
chest, and
▫ any mass that disappears at the clavicles must be
anterior and extends into neck

13. See sharp
margin
above clavicle
Click for lateral view
This
should
help!
Mass is in posterior mediastinum. It remains sharply outlined in apex of thorax,
indicating that it is surrounded by lung.
This particular example is a ganglioneuroma

14. Thoracoabdominal sign
• A sharply marginated mediastinal mass seen through the
diaphragm must lie entirely within the chest.
• The posterior costophrenic sulcus extends far more caudally
than the anterior aspect of the lung
• Therefore
▫ Any mass that extends below the dome of the
diaphragm and remains sharply outlined must be in
the posterior compartments and surrounded by lung,
and
▫ Any mass that terminates at dome of diaphragm must
be anterior

15. Outline
of the Mass
can be seen
below diaphragm
Margin of mass is apparent and below diaphragm, therefore this must
be in the middle or posterior compartments where it is surrounded by
lung
This example is a ‘Lipoma’

16. Right Paratracheal stripe
• The right paratracheal stripe is seen projecting
through the SVC. It is formed by the trachea,
mediastinal connective tissue, and paratracheal pleura
and is visible due to the air–soft tissue interfaces on
either side.
• Paratracheal stripe should be uniform in width with a
normal width ranging from 1 to 4 mm. Right
paratracheal stripe 5 mm or more in width is
considered widened.
• The azygos vein lies at the inferior margin of the
right paratracheal stripe at the tracheobronchial angle.

17. Lymphadenopathy.
(a) On a collimated posteroanterior chest radiograph,the right paratracheal stripe is not
seen, having been obliterated by a right paratracheal mass (arrowheads).
(b) CT scan demonstrates right paratracheal Lymphadenopathy (arrow), which obliterates
the air–soft tissue interface between the right lung and the tracheal wall..

18. Azygoesophageal Recess
• The azygoesophageal recess is the interface between the right
lung and the mediastinal reflection, with the esophagus lying
anteriorly and the azygos vein posteriorly within the
mediastinum.
• On X-ray,it appears as a line –
- in its upper 1/3rd , it deviates to the right at the level of the
carina to accommodate the azygos vein arching forward.
- middle 1/3rd , the line has a variable appearance: It is usually
straight or a minimal convexity to the right may be seen in
adults
- lower 1/3rd , usually straight. ( air in esophagus) .
• It has an interface with the middle mediastinum; thus, the
resulting line seen at radiography can be interrupted by
abnormalities in both the middle and posterior
compartments.

19. Azygoesophageal recess reflection.
(a) Posteroanterior chest radiograph shows the azygoesophageal line (arrowheads).
(b) CT scan shows the azygoesophageal recess (white arrow) formed by the esophagus
anteriorly (black arrow) and theazygos vein posteriorly (arrowhead).

20. Paraspinal Lines
• The paraspinal lines are created by the interface between lung and
the pleural reflections over the vertebral bodies.
• The left paraspinal line is much more commonly seen than the right.
The descending aorta holds the pleural reflection off the vertebral
body, allowing the lung–soft tissue interface to be more tangential
to the x-ray beam.
• On the right, the pleural reflection is more often oblique to the x-ray
beam and therefore less commonly seen.
• The paraspinal lines are disrupted by paravertebral disease—which
commonly includes diseases originating in the intervertebral disks
and vertebrae—and by neurogenic tumors.

21. (a) On a collimated posteroanterior chest radiograph, the left paraspinal line
(arrow) is seen separate and distinct from the vertebral body (black arrowhead) and the
descending thoracic aorta (white arrowhead).
(b) CT scan shows the left paraspinal line. The descending aorta holds the
pleural reflection (arrow) away from the vertebral body, which allows the lung–soft
tissue interface to be more tangential to the x-ray beam and therefore visualized as a line.
(c) Collimated posteroanterior radiograph shows the right paraspinal
line (arrow).

22. Cervicothoracic sign
• Described by Felson:
▫ “If a thoracic lesion is in anatomic contact with the soft
tissues of the neck, its contiguous border will be lost.”
• The anterior mediastinum ends at the level of the clavicles.
• The posterior mediastinum extends much higher.
• Therefore
▫ any mass that remains sharply outlined in the apex of
the thorax must be posterior and entirely within the
chest, and
▫ any mass that disappears at the clavicles must be
anterior and extends into neck

23. See sharp
margin
above clavicle
Click for lateral view
This
should
help!
Mass is in posterior mediastinum. It remains sharply outlined in apex of thorax,
indicating that it is surrounded by lung.
This particular example is a ganglioneuroma

24. Thoracoabdominal sign
• A sharply marginated mediastinal mass seen through the
diaphragm must lie entirely within the chest.
• The posterior costophrenic sulcus extends far more caudally
than the anterior aspect of the lung
• Therefore
▫ Any mass that extends below the dome of the
diaphragm and remains sharply outlined must be in
the posterior compartments and surrounded by lung,
and
▫ Any mass that terminates at dome of diaphragm must
be anterior

25. Can you
see the
outline of the
mass below
the diaphragm?
Margin of mass is apparent and below diaphragm, therefore this must
be in the middle or posterior compartments where it is surrounded by
lung
This example is a ‘Lipoma’

26. Anterior Junction line
• The anterior junction line is seen at posteroanterior
chest radiography.
• The line is formed by the anterior apposition of the
lungs and consists of the four layers of pleura
separating the lungs behind the upper two-thirds of
the sternum
• There is a variable amount of fat between these
layers that can affect the thickness of the anterior
junction line.
• The line runs obliquely from upper right to lower
left and does not extend above the manubriosternal
junction.

27. Anterior junction line.
(a) Posteroanterior chest radiograph demonstrates the anterior junction line(arrow).
(b) (b) Computed tomographic (CT) scan shows the four layers of pleura that constitute the
anterior junction line (arrow).
The interface between aerated lung and pleura allows the line to be appreciated at conventional radiography

28. Posterior Junction Line
• The posterior junction line is a posterior
mediastinal line that is seen above the level of
the azygos vein and aorta and that is formed by
the apposition of the lungs posterior to the
esophagus and anterior to the vertebral bodies,
usually the third to fifth thoracic vertebrae.
• Like the anterior junction line, it consists of four
layers of pleura.
• It appears as a thin straight line projecting
through the trachea, unlike anterior junction
line, it can be seen above the clavicles.

29. (a) Collimated posteroanterior chest radiograph shows the posterior
junction line (arrow) projecting through the tracheal air column.
(b) (b) CT scan shows the posterior junction line (arrow), which is formed by the
interface between the lungs posterior to the mediastinum and consists of four pleural
layers.

31. .
1- Retro-sternal goiter.
2- Tortuous innominate artery.
3- Fat deposition.
4- Enlarged lymph nodes.
5- Ascending aortic aneurysm.
6- Thymoma.
7- Germ cell tumour.
8- Pleuro-pericardial cyst.
9- Morgagni hernia.
10- Para-thyroid adenoma.

32. Thymoma
• Thymoma is the most common primary neoplasm of
the anterior mediastinum but accounts for less than
1% of all adult malignancies.
• Thymomas typically occur in patients older than 40
years of age, being rare in children,and affecting
men and women equally
Associations :
1-Myasthenia Gravis (35% of thymoma patients have
myasthenia gravis)
2-Aplastic Anemia (50% have thymoma)
3-Hypogammaglobulinemia
4-Red cell Aplasia

33. 1-Plain Radiography :
-Presents as an anterior mediastinal mass
-Seen as a well defined lobulated soft tissue density slightly towards one side of the
mediastinum
-Can demonstrate associated calcification (commonly amorphous / flocculent).
2 – CT :CT is the most sensitive technique.
-Appear as homogeneous solid masses with soft-tissue attenuation and well
demarcated borders, located anywhere from the thoracic inlet to the cardiophrenic
angle.
-Thymomas may be oval,round or lobulated and when they are large, cystic or
necrotic degeneration may be shown .
-Calcification may be present in the capsule or throughout the mass.
-Contrast medium enhancement
-Invasive thymomas show growth through capsule into adjacent tissue , drop
metastases into pleural space are common
3 - MRI :
-T1-weighted images : Thymomas commonly appear as homogeneous or
heterogeneous masses with low to intermediate signal intensity.
-T2-weighted images high signal intensity

34. a, b Stage II thymoma (WHO
type B1) in a 33-year-old
woman who presented with
myasthenia gravis.
Frontal chest radiograph shows
a hilum overlay sign (arrow) of
a suggestive anterior
mediastinal mass.
Contrast-enhanced CT scan
confirms the presence of a
lowheterogeneous anterior
mediastinal mass (arrow). Note
the indentation of the arterial
trunk pulmonary by the mass.
c, d Stage III thymoma
(WHO type B2) in a 54-year-
old woman. Frontal chest
radiograph reveals a
lobulatedmediastinal mass
(arrow) on the right side.
Contrast-enhanced
CT scan demonstrates an
enhanced anterior mediastinal
mass (arrow) with infiltration
of surrounding fat (open arrow)

35. CT is the imaging modality of choice for evaluating staging thymoma.
Stage IVa thymoma (WHO type B3) in a 69-year-old woman.
a, b Contrast-enhanced CT scan shows a well-circumscribed, flattened soft tissue lesion in the
anterior mediastinum with calcification (arrow). Note the lobulated contour of the mass and the
loss of the fat plane between the mass and the aorta. Pleural seeding is identified as an enhancing
pleura-based nodule (open arrow).
c Irregular border between the mediastinal mass and the lung parenchyma (arrowhead) is
observed as a sign of locally advanced disease. Note the cellular bronchiolitis in the left lower lobe

36. Axial (a) and coronal multiplanar reconstruction (b) of a noncontrast-enhanced CT scan of a 57-year-old man
allergic to iodine with a thymoma.
A solid lobulated thymic mass (*) with clumps of calcificationswithin (arrowhead) is identified. Note the absence
of a fat plane between the tumour and the aorta (open arrow).
d Coronal T2- weighted MR image shows a typical signal hyperintensity of the tumour lesion (*).
c Axial contrast-enhanced fat-suppressed T1- weighted MR image reveals a homogeneously enhanced solid
tumour(*) which arises from the thymus. Although MRI demonstrates the
presence of fat cleavage plane between ascending aorta and the tumour,a thymoma (WHO type A) with
microscopic transcapsular invasion(Masaoka stage II) was confirmed after surgical resection

37. Axial contrast-enhanced CT images showing a left anterior mediastinal
mass (arrows in a) associated with a left parietal pleural nodule (arrow in b)
and left diaphragmatic pleural nodules (arrows in c), apperances are those
of invasive thymoma with pleural «drop metastases»

38. Thymic cyst
• May be congenital or acquired.
• On plain radiographs, thymic cysts are
indistinguishable from other nonlobulated thymic
masses, notably thymomas.
• CT scans show a well-defined cystic mass
demonstrating CT attenuation values typically
consistent with fluid. The appearance, however, may
vary if haemorrhage or infection complicate the cyst.
Curvilinear calcification of the cyst wall may occur in
a few cases.

40. A well marginated mass with a homogeneous attenuation usually
in the range of water attenuation (0–20 HU) and without an
enhancement of the wall or infiltrative appearance

41. Thymyolipoma
• Thymolipoma is a rare, benign, well-encapsulated thymic tumour that
accounts for about 2–9% of thymic neoplasms.
• Tumours occur most frequently in the cardiophrenic angle of asymptomatic
young adults without sex predilection.
• The fat content usually constitutes 50–85% of the lesion but has been
reported to account for as much as 95% of the tumour .
1-Plain Radiography :
-Typically these tumors appear as large anterior mediastinal masses
-The larger tumors tend to hang down one or either side of the pericardium
and being soft , they mold themselves to the adjacent mediastinum and
diaphragm and often mimic cardiomegaly .May also mimic excessive
epicardial fat, diaphragmatic elevation, lobar collapse or a pericardial cyst.
2-CT :
- Shows a well-defined encapsulated mass that has extensive fat content and
contains small amounts of solid areas and fibrous septa of inhomogenous
soft tissue density.

42. Thymolipoma in a 47- year-old asymptomatic man.
Axial and coronal multiplanar reconstruction of non-contrastenhanced CT
scan show a large and well-defined mass (arrows) that has extensive fat
content and contains small amounts of thin fibrous septa

43. Thymolipoma : a) Chest radiograph showing a widening of the
cardiac silhouette , b) CT confirms the presence of a heterogeneous
mass with fatty components growing in caudal direction

44. Thymic Hyperplasia
a) Pathology :
-It can be subdivided into two forms :
1-True Thymic Hyperplasia
2-Lymphoid Hyperplasia

45. b) Causes :
1-True Thymic Hyperplasia :
a) Rebound hyperplasia to chemotherapy , thymic rebound
hyperplasia (3 to 10 months after the start of chemotherapy)
b) Radiation Therapy
c) Burns
d) Other Severe Systemic Stresses (e.g. pneumonia)
• True thymic hyperplasia is defined as enlargement of the
thymus, which generally retains its normal shape. The
phenomenon known as rebound hypeplasia is defined as a
greater than 50% increase inthymic volume over baseline
after such stress .
• Among patients who undergo chemotherapy, approximately
10–25% may develop rebound hyperplasia

46. Thymic Hyperplasia
2-Lymphoid Hyperplasia :
a) Myaesthenia Gravis
b) SLE
c) Rheumatoid Arthritis
d) Scleroderma
e) Graves Disease
• Diffuse symmetric enlargement of the gland, a smooth contour
and normal vessels are the key morphological features of
hyperplasia, whereas neoplasm tends to manifest as a focal mass
with nodular contour and necrotic or calcified foci.

47. a–c Thymic hyperplasia in a 43-year-old woman (arrows).
a Non-contrast-enhanced CT scan reveals a lobulated lesion with smooth margins in anterior mediastinum.
b Lesion appears slightly hyperintense on in-phase gradient-echo T1-weighted MR image.
c Opposed phase gradient-echo T1-weighted MR image shows decreased signal intensity within the lesion,
confirming presence of fat.d–f Stage II thymoma (WHO type B2) in a 62-year-old woman (arrows).
d Noncontrast- enhanced CT scan shows an anterior mediastinal soft tissue mass. e The lesion shows an
intermediate signal intensity on in-phase gradient-echo T1-weighted MR image.
f There is no substantial decrease in signal intensity.

48. Thymic rebound hyperplasia in an 11 year old girl with Hodgkin lymphoma
(a) CTC shows right sided mediastinal adenopathy (arrow) , Arrowhead = thymus
(b) CT scan obtained after completion of chemotherapy shows regression of the
adenopathy (arrow) , there is early thymic rebound hyperplasia (arrowhead)
(c) CT scan obtained 1 month after chemotherapy shows that the nodal mass has
almost resolved (arrow) and the thymic rebound hyperplasia is nearly complete
(arrowhead)

49. Thymic Carcinoid
Carcinoid tumors (neuroendocrine tumors) of the thymus are very rare,
accounting for <5% of all neoplasms of the anterior mediastinum.
They originate from the normal thymic Kulchitsky cells, which belong to
the amine precursor uptake and decarboxylation (APUD) group
Presentation
• men aged 30 to 50 years
• (male/female ratio: 3:1)
• Rarely associated with carcinoid syndrome
• Associated endocrine abnormalities: Cushing’s syndrome due to ectopic
ACTH or MEN
• 73% have regional lymph node and/or distant osteoblastic bone mets

50. • Thymic carcinoid tumor in a 22-year-old man with a 3-month history of a
persistent dry cough.
• Contrast-enhanced CT scan shows a heterogeneously enhancing thymic mass .
• PET image shows intense FDG uptake by the mass

51. Thymic Carcinoma
• Thymic carcinoma accounts for about 20% of
thymic epithelial tumours with a mean age of 50
years.
• Typical appearance is a multilobulated and
heterogeneous mass that may contain areas of
calcification or haemorrhage.
• Distant metastasis are present at the initial
diagnosis in 50–65% to local lymphatics, lung,
bones,liver and kidney

52. Thyroid Masses
• Thyroid masses that extend into the
mediastinum : goiter > adenoma , carcinoma ,
lymphoma.
a) Plain Radiography :
-Tracheal displacement is the most common
finding by CXR

53. Thyroid goiter
Trachea is
deviated
to left
Mass
disappears
at level of
clavicle

54. b) CT :
- Typical features of mediastinal goitres are encapsulated and lobulated
mass with inhomogeneous appearance with cystic areas, calcifications and
marked contrast enhancement.
-They don’t usually project below the arch of the aorta (differentiating
them from thymomas and teratoma)
The presence of ill-defined margins, invasion of adjacent structures
and nearby lymph node enlargement suggests the diagnosis
of thyroid cancer.

55. Substernal Thyroid Goiter , CT+C of the chest shows a large contrast
enhancing mass in the anterior mediastinal containing calcifications
and areas of necrosis

56. Lymphoma
• Malignant lymphoma accounts for nearly 20% of all mediastinum
neoplasms in adults and 50% in children.
• Lymphomas are the most common cause of masses in the paediatric
mediastinum .
• Hodgkin lymphoma represents approximately 50–70% of
mediastinal lymphomas, while non-Hodgkin lymphoma comprises
15–25%.
• Only 10% of lymphomas which involve the mediastinum are
primary (i.e. mediastinum involvement not part of systemic disease)
and the majority are Hodgkin lymphomas (50-70%).
• Hodgkin’s disease has a bimodal distribution of incidence peaking
in young adulthood and again after the age of 50 years.

57. 2-Pathology :
a) Hodgkin Lymphoma :
1-Lymphocyte Predominant (LP) , <5 %
2-Nodular Sclerosing (NS) , 70%
3-Mixed Cellularity (MC) , 25%
4-Lymphocyte Depleted (LD) , <5%
b) Non – Hodgkin’s Lymphoma
1-Primary mediastinal large B-cell lymphoma
2-Lymphoblastic Lymphoma (T-cell)
Primary mediastinal lymphomas are most frequently of 3
histologic varieties :
1-Nodular Sclerosing Hodgkin lymphoma
2-Primary mediastinal large B-cell lymphoma
3-Lymphoblastic Lymphoma (T-cell)

58. Primary Mediastinal Hodgkin’s Lymphoma
Presentation
• Incidental mediastinal mass on chest xray is 2nd
most common presentation after asymptomatic
lymphadenopathy
• Mass is usually large, rarely causes retrosternal chest
pain, cough, dyspnea, effusions or SVC syndrome
• Bimodal age distribution
• “B” symptoms: fever, weight loss (>10% body wt in 6
months), night sweats
• Generalized pruritus present.

59. a) Plain Radiography :
-A soft tissue mass may be clearly visible or more frequently the mediastinum is
widened and the retrosternal airspace is obscured often showing enlargement of
the prevascular and paratracheal nodes. Hilum overlay sign is positive.
b) CT :
-Characteristic features on imaging are a homogeneous soft-tissue anterior
mediastinal mass with mild to moderate contrast enhancement, irregular
contours, surface lobulation, absence of vascular involvement, and high
prevalence of associated mediastinal lymphadenopathy
-Other features include :
1-Parenchymal invasion , uncommon
2-Pleural effusion
3-Pericardial effusion
4-Chest wall invasion
Calcification is usually seen following therapy and can have varying
morphology including irregular , diffuse or even egg shell
-Lymphomas may have areas of necrosis but they usually do not have cystic areas .

60. Mass
disappears
at level of
clavicle

61. A chest CT exam shows the mass to extend from the neck to the diaphragm,
compressing the tracheal and left mainstem bronchus leading to left lower lobe
atelectasis. The chest wall mass is partially eroding the sternum.
Dx:Lymphoma, Hodgkin, Anterior Mediastinal, Sternal Involvement

62. Two contiguous slices
from an enhanced chest
CT exam show a
homogenous, solid,
anterior mediastinal mass
and a large right pleural
effusion.
Dx-Lymphoma, Non-
Hodgkin, Anterior
Mediastinal

63. A 28-year-old man with Hodgkin lymphoma. Frontal chest radiograph and contrast-enhanced
CT scan show a homogeneous soft tissue mass at the level of the subcarina (arrows).
An aortopulmonary window lymphadenopathy can be detected on CT scan (open arrow).
The right paratracheal stripe is not seen on frontal chest radiograph, having been most
probably obliterated by a right paratracheal lymphadenopathy (arrowhead). * Carina

64. Axial T1-weighted MR image of a 16-year-old man with a
solid, large mass (arrows) in the anterior and superior mediastinum.
Supra-aortic trunks are almost completely surrounded by the lesion and
trachea (T) is displaced to the contralateral side by the lesion. Pathological
analysis demonstrated a T-cell lymphoblastic lymphoma

65. Mediastinal Germ Cell Tumors
• Primary extragonadal germ cell tumors comprise
2% to 5% of all germ cell tumors
• Approximately two thirds of these tumors occur in
the mediastinum
• The mediastinum is the most common site of
primary extragonadal germ cell tumors in young
adults
• Represent 10-15% of adult anterosuperior
mediastinal tumors. Only 3% of them arise in the
posterior mediastinum.

66. Mediastinal Germ Cell Tumors
Three types
• Teratoma
• Seminoma
• Nonseminomatous Germ Cell Tumor

67. Mediastinal Teratomas
• Most common mediastinal germ cell tumor
• Three types:
• Mature: benign, well-differentiated and
predominantly ectodermal element.
• Immature: contains >50% immature components
(fetal tissue or neuroendocrine), may recur or
metastasize.
• Malignant: a mature teratoma that contains a
focus of carcinoma, sarcoma or malignant GCT

68. a) Plain Radiography :
-Anterior mediastinal mass +/- areas of calcifications.
b) CT :
Most commonly appears as a well-defined unilocular or multilocular
cystic lesion containing fluid, soft tissue and fat attenuation .
Calcifications may be focal, rim-like or, in rare cases, representative of
teeth or bone.
C) MRI :
Teratomas typically demonstrate
heterogeneous signal intensity, representing various internal elements.
Fat-fluid levels within the lesion are virtually diagnostic of teratoma.

69. Chest imaging shows well the highly
heterogeneous contents
of mediastinal teratomas.
a Mature cystic teratoma in a 40-year-
old man. Contrast-enhanced CT scan
shows a heterogeneous anterior
mediastinal mass with areas of fat
(open arrow), calcification (arrow) and
fluid attenuation (*).
c Contrast enhanced CT scan of an
asymptomatic 24-year-old woman
demonstrates a well-defined
uniloculated mass located in
prevascular space which shows a cystic
changes within (*). Non foci of
calcification were identified. d The
mass was surgically removed and
pathological examination
confirmed a benign teratoma

70. Teratoma in a 39 year old man , PA chest film shows an anterior
mediastinal mass (A, arrows) , CT shows a large area of fat within
the mass (B, arrow)

71. Seminoma
• Primary mediastinal seminomas comprise 25–
50% of malignant mediastinal GCTs and occur
almost exclusively in males during the period
from the second to fourth decades of life .
• CT : The tumours typically have homogenous
appearance and show minimal contrast
enhancement.
• Areas of degeneration due to haemorrhage and
coagulation necrosis may be present.
• Metastasis to lymph nodes and bone does occur.

72. • A 19-year-old man with seminoma. Contrast-enhanced axial CT scan
demonstrates a large mass in the right side of the mediastinum with an obvious
mass effect on great vessels and heart. The mass shows heterogeneous CT-
attenuation values probably secondary to
haemorrhage and coagulation necrosis. Note also a right pleural
effusion(arrowhead) and multiple lung metastasis (arrows)

73. Mediastinal Nonseminomatous Germ
Cell Tumors
• Five Types
• Embryonal cell carcinoma
• Endodermal sinus tumor: elevated AFP
• Choriocarcinoma: elevated -HCG
• Malignant Teratoma
• Mixed

74. Mediastinal Nonseminomatous Germ
Cell Tumors
• NSGCTs of the mediastinum have a worse
prognosis than mediastinal seminomas or
teratomas
• Occur in men in the 20-40 age group
• 20% of patients also have Klinefelter’s syndrome
• Measuring AFP and ß-hCG levels is important
when making the diagnosis

75. Non-seminomatous malignant germ cell tumour of the anterior mediastinum in a 25-year-old
man Frontal chest radiograph shows a central mass (*). The descending aorta is clearly seen
(arrows), indicating that the mass is not within the posterior mediastinum. Multiple nodules in
bilateral pulmonary field are also observed.
A contrast-enhanced CT scan confirms a mass of low attenuation (*) in the anterior mediastinum
that compresses the pulmonary artery. Bilateral lung metastasis (arrowheads) and hilar and
subcarinal lymphadenopathy is identified (open arrows)

76. Thoracic aortic aneurysm
a) Plain Radiography :
-The thoracic aorta can usually be seen on both frontal and
lateral chest radiographs and aneurysms are often obvious
-Mural calcification is seen both in atherosclerotic disease as
well as various causes of aortitis
b) CT :
-CTA is the work horse of aneurysm assessment
-Typically aneurysms appear as dilatations of the lumen , the
walls may be thin or thickened by presence of mural thrombus
(circumferential or more frequently eccentric)
-Calcified atherosclerotic disease is often identified not only in
the wall of the aneurysm but in adjacent arteries
-If rupture or leak has occurred hematoma / fluid may be seen
adjacent to the aorta , in the left pleural cavity or in the
pericardium

78. Fat Deposition
There is smooth widening of the superior mediastinum
without trachial displacement.
Pleuropericardial cyst:
They appear as a well defined round, oval or triangular
soft tissue mass which can alter in shape on respiration.

79. a Lateral chest radiograph of a 58-year-old smoker man allergic to iodine shows a well-defined
mass (*) in the cardiophrenic space and a nodular lung opacity (open arrow) in the lower lung
parenchyma.
b, c Non-contrast-enhanced CT scan confirms the presence of a fluid attenuation mass (*) in
the right cardiophrenic angle (pericardial cyst)and demonstrates a suspicious lung opacity
(open arrows) in the right lower lobe of the lung (squamous-cell carcinoma)

80. Anterior and middle mediastinal
lymph node enlargement

81. Middle mediastinal masses
The middle mediastinal masses widened the para-tracheal
stripes, displaced the azygo-oesophageal recess on right side.
1- Lymph nodes enlargement.
2- Aortic arch aneurysm.
3- Enlarged pulmonary artery.
4- Dilated superior vena cava.
5- Bronchogenic cyst.
6- Tracheal lesions.
7- Cardiac tumours.

83. Oesophageal duplication cyst
• Uncommon, mostly present in childhood.
• presence of smooth muscle in the walls and
contain mucosa resembling GIT.
• Imaging findings- similar to bronchogenic cyst
- except that the wall of the lesion may be
thicker,
- may assume a more tubular shape,
- and it may be in more intimate contact with
the oesophagus.
- may cause extrinsic compression on barium.

84. Duplication cyst in a 42-year-old asymptomatic man.
a Contrast-enhanced CT scan shows a round well marginated mass (arrow) adjacent
to the oesophagus with homogeneous water-attenuation.
b The lesion (arrow) presents a bright signal intensity on T2-weighted fatsuppressed
MR image

86. ▫ Single slice from an enhanced chest CT exam shows the mass to be
non-enhancing, posterior to the right bronchi, and next to the
esophagus.
▫ Dx: Esophageal Duplication
Duplication cysts are indistinguishable from bronchogenic cysts on CT and MRI.

87. Bronchogenic cyst
• Bronchogenic cysts result from abnormal ventral
budding or branching of the tracheobronchial tree
during embryologic development.
• They are lined by respiratory epithelium and their
capsule contains cartilage, smooth muscle and mucous
gland tissue. They are stable in size,
except when complicated by infection or haemorrhage.
• The bronchogenic cyst is commonly located in the near
carina (52%) and in the paratracheal region (19%).The
anterior mediastinum is a rare location of the
bronchogenic cyst.
• Air within the cyst is suggestive of secondary infection
and communication with the tracheobronchial tree.

88. Bronchogenic cysts
• On the chest radiograph, bronchogenic cysts typically appear as smooth,
sharply marginated mediastinal masses. On CT scans they appear as round
or oval homogeneous masses with well-defined margins with barely or no
perceptible walls.

89. Bronchogenic cyst. (a) Posteroanterior chest radiograph demonstrates a
subcarinal abnormality with increased opacity (*), splaying of the carina, and abnormal
convexity of the upper and middle thirds of the azygoesophageal line (arrowheads).
(b) Corresponding CT scan helps confirm a subcarinal mass (arrow), which proved to
be a bronchogenic cyst.

90. Neuroenteric cyst
• Mediastinal neuroenteric cysts are anomalous
protrusions of the leptomeninges through
intervertebral foramen or defects in the vertebral
body.
• They are associated with multiple vertebral
anomalies and with neurofibromatosis.

91. Aneurysmal dilatation of the main pulmonary artery and the right pulmonary
artery with peripheral pruning due to PH

92. Posterior mediastinal masses
• Neurogenic tumours.
•Pharyngio-esophygeal pouch.
•Descending thoracic aortic aneurysm.
• Esophageal lesions
•Para-vertebral masses.
•Neuroenteric cysts.
•Bochdalek hernia.
•Pancreatic pseudocyst.
•Abscess.
•Fibrosis.
• Extra-medullary hematopoiesis.
•Lateral meningocele.

93. Neurogenic Tumors
-Neurogenic tumors are the cause of approximately 90% of posterior
mediastinal masses
-They can be subdivided into three groups by their location and
involvement of peripheral nerves or sympathetic chain :
1-Peripheral Nerve Sheath Tumors
2-Sympathetic Ganglia Tumors
3-Paraganglioma
-Peripheral nerve sheath tumors and paragangliomas are far more
common in adults while the sympathetic ganglia tumors are
commoner in children

94. Peripheral Nerve Tumors
• Most common(70%) mediastinal neurogenic tumours and
originate from spinal or proximal intercostal nerve; however,
they rarely arise from the vagus, recurrent laryngeal and
phrenic nerve.
• Schwannomas are the most common (50%) mediastinal
neurogenic tumours and frequently affect patients from 20 to
30 years old.
• They are usually solitary and encapsulated masses, but
multiple schwannomas may be associated with
neurofibromatosis type 2.
• The tumour may grow through theadjacent intervertebral
foramen and spinal canal to produce a “dumbbell” or
“hourglass” configuration.
• Cystic changes and haemorrhage are more common in
schwannomas than in neurofibromas.

95. Schwannoma
1-Plain Radiography :
-Both benign and malignant tumors may erode ribs
-They may enlarge the neural foramina (dumbbell shaped lesion)
-Scalloping of posterior vertebral bodies may occur
-They may produce a scoliosis
-Pleural effusion may occur with benign as well as malignant neural tumor.
2-CT :
-Isodense round or oval mass , <2 vertebral bodies long
-Dense contrast enhancement :
Small tumors show homogeneous enhancement
Larger tumors may show heterogeneous enhancement
3-MRI :
*T1 : 70% hypointense , 30% isointense
*T2 : Very hyperintense , may show small internal low signal foci(calcification)
and areas of necrosis
*T1+C : Dense enhancement :
-Homogeneous if small
-Heterogeneous if large

96. PA and lateral chest films show a
mediastinal mass that had enlarged in the 4
year interval that may be spreading the right
5th and 6th ribs apart.

97. Peripheral nerve tumours usually
show a markedly convex
mass arising from the
mediastinum.
a Coronal multiplanar
reconstruction of contrast-
enhanced CT scan of an
asymptomatic 59-year-old man
with a mass in right superior
mediastinum (arrow).
Histological examination
confirmed a schwannoma arising
from the phrenic nerve. b
Schwannoma in a 77-year-old
woman.
Non-contrast-enhanced CT scan
shows a well-defined and
homogeneous paravertebral mass
(*)

98. • An enhanced chest CT exam shows a homogeneous mass, of fatty density,
with a few septations, in the right posterior mediastinum causing some
anterior displacement of the right main stem bronchus.
• Dx:Lipoma, Posterior Mediastinal

99. Coronal T2 shows well defined paravertebral mass with peripheral
high signal intensity and relatively low signal intensity centrally ,
mass has peripheral low signal intensity rim (arrows) that reflects
tumor capsule

100. Axial T2 shows well defined mass with heterogeneous high signal
intensity in right paravertebral region , mass protrudes toward
adjacent right neural foramen (arrow) and shows “dumbbell”
configuration , mass has low signal intensity rim (arrowhead) in
periphery

101. Neuroblastoma in a 20-
year-old man.
Axial (a) and coronal
(b) T2-weighted MR
images, and sagittal (c)
contrastenhanced
T1-weighted MR image
demonstrate an expansive
and heterogeneous mass in
the left paravertebral space
which shows cystic
degeneration within
(*) as well as an intensive
enhancement (in c).
Note the spinal
involvement (arrowhead
in b)

102. Bochdalek hernia

103. C T Scan
• CT has become a routine part of the diagnostic evaluation of
mediastinal tumors, cysts, and other masses.
• The CT scan is very useful in differentiating tissue densities. This
assists greatly in distinguishing structures that are cystic or
vascular from those that are fatty or solid.
• CT is useful in staging of malignant diseases to demonstrate the
mediastinal lymph node enlargment, pulmonary and bony
metastasis in the chest.
• CT is also used to detect the occult diseases in the mediastinum
such as lymph node or thymoma.
• This test can greatly assist in determining the exact location of
the mediastinal tumor and its relationship to adjacent
structures.
• It also is useful in differentiating masses that originate in the
mediastinum from those that encroach upon the mediastinum
from the lung or other structures.

104. Magnetic Resonance Imaging
• MRI offers high resolution multi planar imaging thereby
thereby providing additional information as to the location and
extent of the abnormality.
• It can be used when iodinated contrast is contraindicated.
• It is the preferred modality in evaluating neurogenic tumors
because it provides information regarding the nature and
extent of intraspinal involvement.
• It provides superior vascular images and can help better
delineate the relationship of an identified mediastinal mass to
nearby intrathoracic vascular structures.
• Helps to differentiate between a possible mediastinal mass and
a vascular abnormality such as an aortic aneurysm.

105. Magnetic Resonance Imaging
• MRI is more useful than the CT scan in the evaluation of
invasion or extension of tumors, especially tumors closely
associated with the heart.
• It can be augmented with magnetic resonance angiography if
more extensive evaluation of associated vascular structures is
needed, eliminating the need for separate conventional
angiography studies.
• MRI is used increasingly for evaluation of residual or
recurrent disease after treatment of lymphoma.
• Limitation - this modality does not demonstrate calcification
as well as CT.

106. PET Scan
• The usefulness of this study in the evaluation of mediastinal tumors is
being evaluated It is useful in determining the biological,metabolic
and functional characteristics of the mass than the morphological
features and hence the malignant nature of tumors can be better
identified.
• PET has proven a useful test in for helping identify some
pheochromocytomas.
• Some results of using PET scan for thymomas suggest that a high 18-
fluorodeoxyglucose (FDG) uptake on PET scan reflects the
invasiveness of malignant nature of thymic tumors and can be used to
differentiate these from benign thymomas.
• 18F-FDG PET/CT can play in accurate localization of disease and
evaluation of extranodal involvement in patients with Non-Hodgkin
Lymphoma and Hodgkin’s Disease.

107. Radionuclide scanning
• Nuclear imaging can be used selectively in the workup of mediastinal
masses when specific tumors are suggested.
• Scanning with technetium Tc 99m sestamibi - useful in the identification of
mediastinal parathyroid tissue.
• The iodine I 131 or iodine I 123 scans- distinguishing thyroid tissue from
other masses.
• Gallium Ga 67 - Evaluation of mediastinal lymphoma, both for initial
evaluation and for post therapy follow-up.
• Radionuclide scan is also useful for localizing various neuroendocrine
neoplasms, including carcinoid tumors, pheochromocytomas, and para
gangliomas.

108. Thank You