Diagnostic Imaging of Mediastinal Masses

Diagnostic Imaging of Mediastinal Masses

1. Chest
Mediastinal Masses

2. Mohamed Zaitoun
Assistant Lecturer-Diagnostic Radiology
Department , Zagazig University Hospitals
Egypt
FINR (Fellowship of Interventional
Neuroradiology)-Switzerland
[email protected]

5. Knowing as much as
possible about your enemy
precedes successful battle
and learning about the
disease process precedes
successful management

6. Mediastinum
1-Anterior Mediastinal Masses
2-Middle Mediastinal Masses
3-Posterior Mediastinal Masses

7. Mediastinal lines or stripes are interfaces between the soft tissue of
mediastinal structures and the lung, the aortopulmonary window is
the interface below the aorta and above the pulmonary trunk and is
concave or straight laterally

8. Anterior junction line results from the anterior apposition of the lungs, which lies behind the upper two-
thirds of the sternum, the line consists of four layers of pleura and a variable amount of
intervening fat, it appears as a thin oblique line projecting over the superior two-thirds of the
sternum and runs from the upper right to the lower left, it does not extend above the level of
clavicles, posterior junction line results from the apposition of the lungs posterior to the
esophagus and anterior to the 3rd to 5th thoracic vertebrae, similarly to anterior junction line, it is
formed by 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

9. Mediastinal signs, frontal chest film (a) shows the hilum (arrow), which indicates
that the mass is either anterior or posterior to the hilum, this is the hilum
overlay sign in patient with lymphoma, frontal chest film (b) shows
enlargement of the right superior mediastinum, above the level of the
clavicles, the margins of the mass are sharp (arrow) due to the interface
with adjacent lung, indicating that the mass is located in the posterior
mediastinum

10. 1-Anterior Mediastinal Masses (5Ts)
a) Thymus Abnormalities
b) Thyroid Masses
c) Terrible Mediastinal Lymphoma
d) Germ Cell Tumors
e) Thoracic Aortic Aneurysm
f) Pericardial Cyst
g) Morgagni Hernia
h) Sternal Tumors
i) Pericardial Fat Pad

11. -The anterior mediastinum is that portion
of the mediastinum anterior to the
pericardium and below the level of
the clavicles
-It includes the thymus , lymph nodes and
may contain the portions of a retrosternal
thyroid

13. a) Thymus Abnormalities :
1-Thymoma
2-Thymolipoma
3-Benign Thymic Hyperplasia
4-Thymic Cyst

14. -On frontal chest radiographs in
infants and young children , the
thymus is strikingly large but
difficult to discriminate from the
cardiac silhouette
-The thymus usually has smooth
borders and remains visible on
radiographs through the age of 3
years
-The thymic wave sign , a scalloped
or wavy contour of the organ is
created by the impression of the
anterior reflection of the ribs
-The thymic sail sign , a triangular
slightly convex right lobe of the
thymus with a sharply demarcated
base caused by the minor fissure

15. -Typically , the thymus is
visible at CT and fills the
perivascular space
throughout the first 2
decades of life
-In children younger than 5
years , it typically appears
quadrilateral with convex
borders
-As children grow , the
thymus gradually
becomes triangular with
straight or concave
border

16. 1-Thymoma :
a) Incidence
b) Associations
c) Pathology
d) Radiographic Features

17. a) Incidence :
-Thymoma is the most common anterior
mediastinal tumor in the adult (very rare in
children)

18. b) Associations :
1-Myasthenia Gravis (35% of thymoma
patients have myasthenia gravis)
2-Aplastic Anemia (50% have thymoma)
3-Hypogammaglobulinemia
4-Red cell Aplasia

19. c) Pathology :
1-Benign Thymoma, 75% :
-Common in patients with myasthenia
2-Malignant Thymoma , 25% :
-Local spread into pleura but no
hematogenous metastases
-More common in patients without
myasthenia

20. d) Radiographic Features :
1-Plain Radiography
2-CT

21. 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)

26. 2-CT :
-Anterior mediastinal soft tissue mass :
1-Asymmetrical location on one side
2-Homogeneous density and signal intensity
3-Some have cystic components (40% of the cases and
are mostly focal)
4-Contrast medium enhancement
5-Invasive thymomas show growth through capsule into
adjacent tissue , drop metastases into pleural space are
common
6-Calcification , 20 %

31. CT shows anterior mediastinal masses with coarse calcifications (A) and a
circular peripheral calcification (B)

32. Cystic thymoma , CT+C shows a low attenuation lesion (arrow) in the anterior
mediastinum

33. Invasive thymoma with pleural metastases

34. 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»

35. Thymoma with no signs of mediastinal fat invasion (A, arrows) , one year after
surgery , pleural metastasis was found (B, arrow)

36. 2-Thymolipoma :
a) Incidence
b) Associations
c) Pathology
d) Radiographic Features

37. a) Incidence :
-Is a rare benign anterior mediastinal
mass of thymic origin
-Comprises 2-9% of all thymic neoplasms
-Mean age of 22 years
-Tumors usually grow to large sizes (75%
are >500 g) with few or no symptoms

38. b) Associations :
1-Myasthenia Gravis (in 3 % of thymolipoma)
2-Aplastic Anemia
3-Hypogammaglobulinemia
4-Grave’s Disease
c) Pathology :
-Thymolipomas are composed of a mixture mature
adipose tissue with islands of thiymic tissue

39. d) Radiographic Features :
1-Plain Radiography
2-CT

40. 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

42. 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. 2-CT :
-On CT thymolipomas typically appears
almost entirely fatty with some areas of
inhomogeneous soft tissue density that
represent thymic tissue

47. CT show a large and well defined mass (arrows) that has extensive fat content
and contains small amounts of thin fibrous septa

49. 3-Benign Thymic Hyperplasia :
a) Pathology
b) Causes
c) Radiographic Features

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

51. 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)

52. 2-Lymphoid Hyperplasia :
a) Myaesthenia Gravis
b) SLE
c) Rheumatoid Arthritis
d) Scleroderma
e) Graves Disease

53. c) Radiographic Features :
-Diffuse symmetric enlargement of the gland is
the key morphologic feature of hyperplasia
(neoplasm tends to manifest as a focal mass)
-Size and morphology of normal thymus :
>20 years of age : <13 mm
>30 years of age : Convex margins are abnormal
-No increase in size over time

54. Thymic rebound hyperplasia in an 18 month old girl recovering from pneumonia
(a) Frontal chest radiograph shows air trapping and bilateral perihilar peribronchial infiltrates (arrows) ,
findings consistent with viral pneumonia
(b) Follow-up radiograph shows thymic rebound hyperplasia (arrowheads) and resolution of the
pneumonic infiltrates (arrows)

55. 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)

56. Dramatic thymic rebound hyperplasia in a 14 year old boy who
completed chemotherapy for primary mediastinal T-cell lymphoma 6
months earlier

59. 4-Thymic Cyst :
a) Causes
b) Radiographic Features

60. a) Causes :
1-Congenital :
-Contains thymic tissue in wall : often unilocular
2-Acquired : often multilocular
a) Secondary to thoracotomy
b) Following chemotherapy or radiotherapy for
mediastinal malignancy
c) Inflammatory

61. b) Radiographic Features :
1-Plain Radiography
2-CT

62. 1-Plain Radiography :
-Thymic cysts usually appear as
homogeneous circumscribed masses that
may have calcified rims

64. 2-CT :
-Thin walls and no solid component and
show no contrast enhancement

65. CT+C shows inhomogenous unilocular low attenuation mass (arrows)
in the anterior mediastinum

66. 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

67. Cystic changes of the thymus and lymph nodes at diagnosis in a 19
year old man with Hodgkin lymphoma , CT+C shows a solid (arrow
in a) and cystic (arrows in b) thymic mass , by the time the patient
completed chemotherapy , the cystic nodes had resolved but the
cystic areas in the thymus remained unchanged

68. Cystic change of the thymus in a 28 year old man with Hodgkin
lymphoma treated 3 years earlier , CT+C shows a thymic cyst
(arrow) and thymic rebound hyperplasia (arrowhead)

69. b) Thyroid Masses :
1-Incidence
2-Radiographic Features

70. 1-Incidence :
-Thyroid masses that extend into the
mediastinum : goiter > adenoma ,
carcinoma , lymphoma

71. 2-Radiographic Features :
a) Plain Radiography
b) CT

72. a) Plain Radiography :
-Tracheal displacement is the most common
finding by CXR

74. CXR of a partial substernal goiter compressing the trachea from the right side

78. b) CT :
-Mass is contiguous with cervical thyroid and is
well defined
-Heterogeneous density by CT : calcium , iodine
(70 to 120 HU) , colloid cysts
-Marked and prolonged contrast enhancement
-They don’t usually project below the arch of the
aorta (differentiating them from thymomas and
teratoma)
-Nuclear scan with either 99mTc or 123I confirms
the diagnosis

79. Frontal (a) view of the chest radiograph shows an opacity on the right side of
the trachea (arrow), which appears shifted contralaterally and reduced in
caliber, unenhanced CT scans (b-d) demostrate a heterogenous mass
which goes down into the anterior mediastinum referred to a goiter

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

81. CT of a partial substernal goiter compressing the trachea from the left side

82. c) Mediastinal Lymphoma :
1-Incidence
2-Pathology
3-Radiographic Features

83. 1-Incidence :
-Lymphomas are responsible for 45%
of anterior mediastinal masses in children
-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%)

84. 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) B-Cell Neoplasms
c) T-Cell Neoplasms

85. -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)

86. 3-Radiographic Features :
a) Plain Radiography
b) CT

87. a) Plain Radiography :
-A soft tissue mass may be clearly visible or more
frequently the mediastinum is widened and
the retrosternal airspace is obscured
-The hilum overlay sign refers to an appearance on
frontal chest radiographs of patients with a mass
projected at the level of the hilum which is in fact either
anterior or posterior to the hilum , when a mass arises
from the hilum, the pulmonary vessels are in contact with
the mass and as such their silhouette is obliterated , the
ability to see the edges of the vessels through the mass
implies that the mass is not contacting the hilum and is
therefore either anterior or posterior to it , most of these
masses are found to be in the anterior mediastinum

88. Normal Obliteration of the retrosternal space in mediastinal lymphoma

89. Hilum Overlay Sign

94. b) CT :
-Soft tissue attenuating mass with smooth or
lobulated margins which conforms to
surrounding structures (prevascular ,
paratracheal) involvement
-Other features include :
1-Parenchymal invasion , uncommon
2-Pleural effusion
3-Pericardial effusion
4-Chest wall invasion

95. -Calcification is usually seen following
therapy and can have varying morphology
including irregular , diffuse or even egg
shell
-Lymphomas have areas of necrosis but
they usually do not have cystic areas ,
thymic cysts can occur after irradiation of
mediastinal lymphomas or chemotherapy

96. Large soft tissue mass in the anterior mediastinum which
arises in the thymus , there is associated paratracheal
adenopathy (arrow)

98. Anterior mediastinal mass with bilateral pleural effusion

101. 28 year old woman with Hodgkin disease , chest radiograph shows an
anterior mediastinal mass (A, arrow) which on axial CT is irregular
and shows areas of necrosis (B, arrows)

106. d) Germ Cell Tumors :
1-Incidence
2-Pathology
3-Radiographic Features
4-Differential Diagnosis

107. 1-Incidence :
-Germ cell tumors are the most common
cause of a fat containing lesions in the
anterior mediastinum and the second
most common cause of an anterior
mediastinal mass in children

108. 2-Pathology :
-Tumors arise from rests of primitive cells and are
of variable malignant potential (SECTE)
a) Seminoma
b) Embryonal cell carcinoma
c) Choriocarcinoma
d) Teratoma (70% of germ cell tumors) ,
teratocarcinoma
e) Endodermal sinus tumors (yolk sac tumors)

109. 3-Radiographic Features :
a) Plain Radiography
b) CT

110. a) Plain Radiography :
-Anterior mediastinal mass +/- areas of
calcifications

114. 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)

116. b) CT :
-Benign teratoma (90%) is a well defined thick wall
cystic mass containing a variable mixture of :
Calcification , 30%
Fat , fat-fluid levels
Cystic areas
Soft tissue
-Mature teratoma can be very large and still be
benign
-Malignant teratoma (10%) tends to have irregular
or nodular walls and a predominance of soft
tissue components , may show pulmonary or
liver metastases and chest wall invasion

117. Extensive mediastinal involvement (A,B, white arrows) , cystic upper
mediastinal mass (A,B red arrows) , immature tooth (B, yellow arrow)

118. 42 year old man with a teratoma , note the coarse calcifications (A,B,
white arrows) and areas of fat attenuation measuring -103 HU (A,B,
red arrows)

119. CT+C shows large septated anterior mediastinal mass
containing fat and bony elements

120. CT+C shows an anterior mediastinal mass containing calcification (black arrow)
, fat (white arrow) and soft tissue components (dotted white arrow)

121. Benign Teratoma

122. Benign Teratoma

123. Malignant Teratoma

125. 4-Differential Diagnosis :
-From Mediastinal Masses Containing Fat
a) Teratodermoid
b) Diaphragmatic Hernia
c) Lipoma
d) Liposarcoma
e) Thymolipoma
f) Mediastinal Lipomatosis
g) Hamartoma
h) Chylolymphatic Cyst

126. e) Thoracic Aortic Aneurysm :
1-Incidence
2-Pathology
3-Radiographic Features

127. 1-Incidence :
-Are relatively uncommon compared to
abdominal aortic aneurysm

128. 2-Pathology :
-Thoracic aortic aneurysms can be divided
pathologically according to their relationship to
the aortic wall :
a) True Aneurysm :
1-Atherosclerotic aneurysms (most common)
2-Inflammatory / Aortitis :
-R.A. , Ankylosing Spondylitis , Giant cell Arteritis
& Syphilis

129. 3-Structural : Cystic media necrosis
-Marfan disease
-Ehlers-Danlos syndrome
b) False Aneurysm :
-Trauma
-Mycotic aneurysm

130. 3-Radiographic Features :
a) Plain Radiography
b) CT

131. 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

135. 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

138. Dissecting Aoritc Aneurysm

139. f) Pericardial Cyst :
1-Incidence
2-Location
3-Radiographic Features
4-Differential Diagnosis

140. 1-Incidence :
-Uncommon benign congenital anomaly of
the anterior mediastinum
-Incidental findings in asymptomatic patients
, usually after age 30

141. 2-Location :
-Found in the right anterior cardiophrenic
angle but can be found almost anywhere
adjacent to the heart

142. 3-Radiographic Features :
a) Plain Radiography
b) CT

143. a) Plain Radiography :
-Well defined round or oval masses located
in the normally clear cardiophrenic angle

148. b) CT :
-Usually appears as a well defined non-
enhancing low (water) attenuating
rounded mass next to the pericardium

154. Typical benign pericardial cyst with serous content in a 46-year-old
woman, (a) Coronal T1 shows a round low-signal-intensity cyst with
a regular thin wall, (b) T2 shows a homogeneous high-signal-
intensity cyst without septation or a mural nodule

155. 4-Differential Diagnosis : From cystic mediastinal mass :
1-Congenital :
a) Bronchogenic cyst , usually subcarinal or right
paratracheal site
b) Enteric cyst , paraoesophageal site
c) Neuroenteric cyst , associated anomaly of spine
2-Pericardial cyst , usually cardiophrenic angle
3-Thymic cyst , can develop following radiotherapy for
Hodgkin’s disease
4-Cystic tumors :
a) Lymphangioma
b) Teratoma
c) Teratodermoid
5-Pancreatic pseudocyst , can track up into mediastinum
6-Meningocele , 75% association with NF
7-Chronic abscess
8-Old hematoma

156. g) Morgagni Hernia :
-See Congenital Pulmonary Lesions

157. Morgagni hernia in a 2 year old child , lateral chest radiograph shows
herniation of a bowel loop (arrows) in a classic location through an
anteromedial defect

159. h) Sternal Tumors :
-Metastases are the most common (breast ,
bronchus , kidney & thyroid)
-Malignant primary tumors (chondrosarcoma
, myeloma , reticulum cell sarcoma and
lymphoma) are more common than benign
(chondroma , Aneurysmal bone cyst and
Giant cell tumor)

162. i) Pericardial Fat Pad :
-Especially in obese people
-A triangular opacity in the cardiophrenic
angle on the PA view
-It appears less dense than expected
because of the fat content

163. Epicardial fat pad , (a) PA chest radiograph shows loss of the cardiac
silhouette at the border of the right side of the heart and an
epicardial fat pad with relatively low density (arrow) , (b) CT scan
shows the fat pad (arrow) as an area of homogeneous fat
attenuation adjacent to the right border of the heart

164. -Differential Diagnosis : Cardiophrenic angle
lesions
1-Pericardial fat pad
2-Pericardial cyst
3-Pericardial fat necrosis
4-Morgagni’s hernia
5-Lymphadenopathy : metastases , lymphoma
6-Pericardial lipomatosis

165. 2-Middle Mediastinal Masses : (A+B)
1-Adenopathy
2-Aortic Aneurysm
3-Bronchogenic Cyst
4-Carcinoma of the Bronchus

166. 1-Adenopathy :
-The paratracheal , bronchopulmonary and / or
subcarinal nodes may be enlarged
-This may be due to :
a) Neoplasm (Lymphoma , Leukemia & Mets)
b) Infection (most commonly T.B. , Histoplasmosis
or coccidiodomycosis)
c) Sarcoidosis
d) Hyperplasia (Castleman’s disease)

167. a) Neoplasm (Lymphoma , Leukemia & Mets) :
-See Lung neoplasms
b) Infection (most commonly T.B. ,
Histoplasmosis or coccidiodomycosis) :
-See Pulmonary Infections
c) Sarcoidosis :
-See Diffuse Lung Lesions

169. PA chest radiograph shows the right paratracheal stripe (arrow) , the azygos vein is seen at the
inferior margin of the stripe at the tracheobronchial angle (arrowhead) , (b) CT shows the right
wall of the trachea with medial and lateral air soft tissue interfaces caused by air within the
tracheal lumen and right lung (arrow) , these interfaces create the right paratracheal stripe , note
the position of the SVC (arrowhead) which explains why the paratracheal stripe is seen projecting
through the SVC at radiography , (c) CT obtained at the level of the azygos arch shows that the
azygos vein (arrow) disrupts the lung tracheal wall interface at the tracheobronchial angle

170. Lymphadenopathy , (a) PA chest radiograph , the right paratracheal stripe is not
seen having been obliterated by a right paratracheal mass (arrowheads) ,
(b) CT shows right paratracheal lymphadenopathy (arrow) which obliterates
the air soft tissue interface between the right lung and the tracheal wall , this
finding explains the obliteration of the right paratracheal stripe in a

171. PA chest radiograph , the AP window reflection (arrowhead) extends from the aortic knob
to the left pulmonary artery and has a normal concave appearance , the aortic
pulmonary reflection (arrow) is a more anterior line and extends from the aortic arch
to the level of the left main bronchus

172. AP window lymphadenopathy , (a) Chest radiograph shows the AP
window with an abnormal convex border (arrow) , (b) CT shows
lymphadenopathy (arrow) which accounts for the distortion of the AP
window in a

173. Paratracheal lymph node enlargement in metastatic carcinoma

174. Frontal Chest X-ray (a,b) shows a slightly convex border of the aortopulmonary
window (arrow) suspicious for the presence of a mass in the middle
mediastinum, CT scan shows enlarged lymphnodes in the aortopulmonary
window (arrow), causing the abnormality seen on chest radiography, it was
a lymphoma in a 11-year-old-girl

175. Paratracheal and aortopulmonary window lymph node
enlargement

176. Subcarinal lymph node enlargement in CLL

177. Frontal (a) and lateral (b) chest X-ray show a bilateral hilar enlargement, more
evident on the right, CT+C (c,d) showing bilateral hilar lymph nodes in
patient with sarcoidosis

178. d) Giant Benign Lymph Node Hyperplasia
(Castleman’s disease) :
1-Incidence
2-Pathology
3-Radiographic Features

179. 1-Incidence :
-Rare
-Age < 30 years
-Large benign mediastinal lymph node
masses
-Etiology is unknown (nodal hyperplasia vs
benign tumor)

180. 2-Pathology :
-Two histologic types :
a) Hyaline vascular , 90%
b) Plasma cell , 10%

181. 3-Radiographic Features :
-Bulky mediastinal mass lesion (3 to 12 cm) :
anterior > middle > posterior mediastinum
-Dense homogeneous contrast enhancement is
the key feature (vascular lesions)
-On CT, 5% to 10% of Castleman disease showed
intralesional calcifications, typically being
discrete in morphology
-Dynamic CT demonstrates early rapid
enhancement with washout in the delayed phase

182. PA chest Radiograph shows
widening of upper
mediastinum ,
aortopulmonary and
azygos adenopathy and
enlargement of hila
(arrows) with extension of
lesion below right hilum

184. Unenhanced CT using bone window setting reveals posterior
mediastinal mass (arrow) with typical arborizing pattern of
intralesional calcifications

185. CT+C shows matted lymphadenopathy (arrows) formed by confluence
of inhomogeneously enhancing enlarged lymph nodes confined to
anterior mediastinum

187. 2-Aortic Aneurysm :
-See before

188. Aneurysm of the aortic arch. (a) PA chest radiograph shows the AP window with a convex
border (arrow) , (b) CT reveals an aneurysm (arrow) arising laterally from the aortic
arch , a finding that accounts for the abnormality seen in a

190. 3-Bronchogenic Cyst :
-See Congenital Pulmonary lesions

191. (a) PA 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

193. CT+C : well circumscribed unilocular water attenuation cyst in the
middle mediastinum , the cyst has smooth imperceptible walls with
no enhancement

194. Bronchogenic cyst , CT shows a subcarinal mass with fluid density

195. CT Scanogram (a) shows an oval, huge, mass (arrows) that cause a widening
and distortion of azygoesophageal recess, coronal (b) and sagittal (c) MPR
reconstruction demonstrate a cyst with uniform water attenuation and with
an imperceptible wall, this was a bronchogenic cyst

196. Bronchogenic cyst in a 49-year-old man with a 2-week history of fever and
cough, (a) Chest radiograph shows a round mass (arrow) that displaces the
right primary bronchus superiorly, as well as pneumonia of the middle lobe
and pleural effusion, (b) Contrast material-enhanced CT scan shows a cyst
with uniform water attenuation and with an imperceptible wall.

197. Bronchogenic cyst in a 44-year-old woman with a 3-year history of
chest pain, CT scan shows a thin-walled water-attenuation cyst in
the posterior mediastinum (arrow)

198. 4-Carcinoma of the Bronchus :
-See Pulmonary Tumors

202. a) A 55 yr old dyspnoeic
female , chest radiograph
shows widened
mediastinum particularly
on the right with reduced
vascularity of the right
lung
b) CT+C shows central
mediastinal mass
invading the right
pulmonary artery , small
cell carcinoma was
confirmed on
percutaneous biopsy

203. 3-Posterior Mediastinal Masses (ACTH)
1-Posterior Mediastinal Neural Tumors
2-Extrameduallary Hematopoiesis
3-Paraspinal Abscess
4-Descending Aortic Aneurysm
5-Oesophageal Duplication Cyst
6-Neuroenteric Cyst
7-Pancreatic Pseudocyst
8-Bochdalek Hernia
9-Hiatus Hernia
10-Lateral Meningocele

204. 1-Posterior Mediastinal Neural Tumors :
a) Incidence
b) Peripheral Nerve Sheath Tumor
c) Sympathetic Ganglia Tumors
d) Paraganglioma

205. a) Incidence :
-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

206. b) Peripheral Nerve Sheath Tumor :
1-Incidence
2-Schwannoma
3-Neurofibroma
4-Malignant Peripheral Nerve Sheath
Tumors

207. 1-Incidence :
-These tumors manifest as round paravertebral
masses that span one or two vertebral bodies
-They are homogenous soft tissue attenuation
masses at CT and the commonest cause of
posterior mediastinal and paravertebral masses
-They may cause widening of the neural foramen
and thickening of the adjacent posterior rib

210. 2-Schwannoma :
a) Incidence
b) Location
c) Radiographic Features

211. a) Incidence :
-Are benign tumors of schwann cell origin
and are the most common tumor of
peripheral nerves
-Peak presentation is in the 5th-6th decades
-When they occur in patients with
neurofibromatosis type 2 (NF2)
schwannomas usually present by the 3rd
decade

212. b) Location :
-Arise posteriorly , frequently in neural
foramina

213. 1-Vertebral Body
2-Neural Foramen
3-Articular Pillar
4-Lamina
5-Spinous Process

215. c) Radiographic Features :
1-Plain Radiography
2-CT
3-MRI

216. 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

217. There is an opacity in the left posterior mediastinum , there is associated
widening of the 4th intercostal space posteriorly with scalloping of the
inferior margin of the 4th rib , there is also some coarse calcification within
the lesion

221. Cervical X-Ray (a-b) demonstrate a marginated and round opacity
(white arrows), with disrupting of left paravertebral stripe, CT scan
(c) confirms a left hypodense and homogeneous paravertebral
mass, this mass revealed features consistent with schwannoma

222. 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

225. CT+C

228. 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

230. T1

231. T2

232. 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

233. 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

234. Axial T1+C shows heterogeneous enhancement that is relatively strong
in center of mass

235. T1+C

236. T1

237. T2

238. T1+C

239. A, Coronal T2 shows well-
defined mass in right
paravertebral region ,
mass has very high signal
intensity area (arrow) in
center and low signal
intensity rim (arrowhead)
in periphery
B, Coronal T1+C fat-
suppressed shows no
enhancement of central
area (arrow) which
reflects cystic change in
mass

240. 3-Neurofibroma :
a) Incidence
b) Location
c) Radiographic Features

241. a) Incidence :
-Are benign peripheral nerve sheath tumors
-Peak presentation is between 20 and 30
years of age
-The majority of neurofibromas are solitary
and sporadic , however there is an
association with NF1

242. b) Location :
-Arise posteriorly , frequently in neural
foramina

243. c) Radiographic Features :
1-Plain Radiography
2-CT
3-MRI

244. 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

245. Neurofibroma (red arrow) , multiple subcutaneous neurofibromas (yellow
arrows)

246. Posterior scalloping of lumbar vertebral bodies in NF

248. 2-CT :
-Well defined hypodense mass
-Minimal or no contrast enhancement

251. Rib notching with Dumbbell-shaped Neurofibroma

252. 3-MRI :
*T1 :
-Hypointense
*T2 :
-Hyperintense
-A hyperintense rim and central area of low signal
resulting in a target sign may be seen due to a
dense central area of collagenous stroma
*T1+C :
-Heterogenous enhancement

253. T1+C , dumbbell shaped neurofibroma with intra and
extraspinal extension , note the displacement of the
adjacent thoracic cord (arrow)

254. Axial T2 shows well defined mass with homogeneous high signal intensity in left
paravertebral region , mass has thin low signal intensity rim (arrows) in
periphery

255. Target sign in Neurofibroma

256. 4-Malignant Peripheral Nerve Sheath
Tumors (MPNST) :
-Are malignant forms of neurofibromas and
schwannomas
-Associated with NF1
-Imaging criteria are generally considered
unreliable in differentiating from a more
benign neurofibroma or schwannoma

257. c) Sympathetic Ganglia Tumors :
1-Incidence
2-Neuroblastoma
3-Ganglioneuroma
4-Ganglioneuroblastoma

258. 1-Incidence :
-These tumors tend to present as elongated
paraspinal masses that span multiple vertebral
levels
-Intratumoural calcification is common
-They are :
a) Neuroblastoma : young children
b) Ganglioneuroma : children and adults
c) Ganglioneuroblastoma : older children
-Neuroblastoma and ganglioneuroblastoma are
most commonly seen in children and in a child
they comprise the commonest neurogenic tumor

259. 2-Neuroblastoma :
a) Incidence
b) Location
c) Radiographic Features

260. a) Incidence :
-Is a tumor of neuroblastic origin and the most
common extracranial solid childhood
malignancies and the third commonest
childhood tumor after leukemia and brain
malignancies
-The tumors typically occur in infants and very
young children (mean age of presentation being
22 months) with 95% of cases diagnosed before
the age of 10 years

261. b) Location :
-Neuroblastomas arise from the sympathetic
nervous system
-Posterior mediastinum : 20%

262. c) Radiographic Features :
1-Plain Radiography
2-CT
3-MRI

263. 1-Plain Radiography :
-Appearances are non-specific , typically
shows an intrathoracic soft tissue mass
-Pressure on adjacent bones may cause
remodeling of ribs , vertebral bodies or
pedicle thinning
-Up to 30% may have evidence of
calcification on the plain film

264. Homogenous opacity lesion in the right upper and mid zone with broad base towards
mediastinum , the lesion is causing shift of mediastinum and trachea to the
contralateral side and compressing the trachea just above the carina (arrow head) ,
the lesion is extending above the clavicle (cervico-thoracic sign) and erosion of
posterior end of third and fourth ribs (Long arrow)

265. *N.B. : Cervico-thoracic sign
-A variant of the silhouette sign
-It helps to discern the anterior or posterior location of mass
in the superior mediastinum on frontal chest radiographs
-As the anterior mediastinum ends at the level of
the clavicles and as such the upper border an anterior
mediastinal lesions cannot be visualized extending
above the clavicles
-Any lesions with a discernible upper border above that
level must be located posteriorly in the chest ; i.e. apical
segments of upper lobes , pleura or posterior
mediastinum

268. 2-CT :
-The tumor typically is heterogeneous with calcifications
seen in 80 - 90% of cases
-Areas of necrosis are of low attenuation
-The morphology of is often most helpful with the mass
seen insinuating itself beneath the aorta and lifting it off
the vertebral column , it tends to encase vessels and
may lead to compression , adjacent organs are usually
displaced
-Lymph node enlargement is often present
-Calcification in a posterior mediastinal mass points to a
neural tumor in a kid rather than a met from somewhere
else

269. Heterogeneously enhancing mass lesion in the right posterior
mediastinum extending to middle mediastinum causing compression
of the trachea , the lesion is showing multiple small foci of
calcification (black arrows)

273. 3-MRI :
*T1 :
- Heterogeneous and iso to hypointense
*T2 :
-Heterogeneous and hyperintense
-cystic / necrotic areas very high intensity
*T1+C :
-Variable and heterogeneous enhancement

274. 1 month old boy with mediastinal neuroblastoma , coronal T2 shows long
vertically oriented mass with homogeneous high signal intensity and
tapering appearance in left paravertebral region , invasion of vertebrae is
not seen

275. Axial T2 in a patient with a thoracic neuroblastoma shows a large right posterior
mediastinal mass extending into the spinal canal and displacing the cord laterally to
the left , the mass is hyperintense on T2

276. T1+C shows inhomogeneous enhancement of the mass which appears
to have a component arising from the neural foramen (white arrow)

277. 3-Ganglioneuroma :
a) Incidence
b) Location
c) Radiographic Features

278. a) Incidence :
-They tend to occur in the pediatric
population and are often asymptomatic
-Usually , patients are older than 10 years
old , compared to neuroblastoma which
occurs in patient younger than 3 years old

279. b) Location :
-Can potentially occur anywhere along the
peripheral autonomic ganglion sites , the
posterior mediastinum one of the
commonest locations (40%)

280. c) Radiographic Features :
1-Plain Radiography
2-CT
3-MRI

281. 1-Plain Radiography :
-All neuroblastic tumors (i.e.
ganglioneuroblastomas , ganglioneuromas
and neuroblastomas) look similar
-See Neuroblastoma

282. Chest radiograph shows a right paraspinal well-defined density in the
retrocardiac region , the right cardiophrenic angle appears normal

283. 2-CT :
-Typically seen as well circumscribed solid
encapsulated masses
-Tend to be iso to hypoattenuating to muscle
-May demonstrate calcifications (40%)
-Delayed heterogeneous uptake of contrast

287. Paraspinal Ganglioneuroma, non-enhanced Axial CT scan reveals a
paraspinal homogeneous low attenuation fusiform mass which after
resection proved to be a ganglioneuroma

288. 3-MRI :
*T1 :
-Homogeneously low or intermediate signal
*T2 :
-Heterogenously intermediate or high signal
*T1+C :
-Ranging from none to heterogenous
enhancement

289. (a) Chest radiography shows an oblong mass in the right paraspinal region , the lateral
margins of the mass are indistinct & there is RT lower lobe pneumonia , (b) CT+C
shows that the mass is heterogenous and contains calcifications (c) T2 shows that
the mass is of high signal intensity

290. Coronal T2 shows long vertically oriented mass with heterogeneous
high signal intensity and tapering appearance in left paravertebral
region

291. , Coronal T1+C shows heterogeneous enhancement in
mass.

292. T1+C of a ganglioneuroma shows homogeneous enhancement of the
lesion , the lesion is extending from the right paraspinal region into
the epidural space through the neural foramina causing cord
compression

293. T1 of a ganglioneuroma , the sagittal views shows a well-defined solid
mass located slightly anterior to the midthoracic vertebral bodies ,
the mass extends into and widening multiple neural foramina , flow
voids within the lesion represents vascularity

294. 4-Ganglioneuroblastoma :
a) Incidence
b) Location
c) Radiographic Features

295. a) Incidence :
-Uncommon peripheral neuroblastic tumor
- Most commonly in babies and in young
children
-Ganglioneuroblastoma have intermediate
malignant potential between that of
neuroblastomas and ganglioneuromas

296. b) Location :
-Can potentially occur anywhere along the
peripheral autonomic ganglion sites , the
posterior mediastinum one of the
commonest locations

297. c) Radiographic Features :
1-Plain Radiography
2-CT
3-MRI

298. 1-Plain Radiography :
-See Neuroblastoma

300. 2-CT :
-See Ganglioneuroma + areas of bleeding
and necrosis may be as large as 4 cm and
appear to be of lower attenuation

301. CT without contrast of a ganglioneuroblastoma demonstrates a large
left heterogeneous paraspinal lesion with speckled calcifications that
are predominantly peripheral , the mass is displacing the
mediastinum to the right

303. 3-MRI :
-See Ganglioneuroma + areas of hemorrhage
have a high T1 signal intensity and cystic areas
have a high T2 signal intensity
-Ganglioneuroblastomas , like neuroblastomas and
other malignant tumors have an enhancing
pattern of early enhancement followed by a
partial washout , early enhancement is indicative
of high vascularity

304. Axial T1 shows high signal intensity areas (arrowheads) that suggest
hemorrhage in center of mass

305. Axial T1+C shows heterogeneous enhancement in mass ,
enhancement is not seen in center of mass (arrowheads) and tumor
necrosis is suspected

308. MRI scan showing homogenous soft tissue density mass in the posterior
mediastinum

309. d) Paraganglioma :
1-Incidence
2-Location
3-Radiographic Features

310. 1-Incidence :
-Rare tumors derived from chromaffin cells
(neuroectodermal cells) associated with
sympathetic ganglion of the autonomic
nervous system
-Paraganglioma (= chemodectoma ,
histologically similar to
pheochromocytoma) : functional tumors ,
may secrete catecholamines

311. 2-Location :
-They can arise from two major cluster of
sympathetic ganglion cells :
a) Paraaortic (aorticopulmonary)
b) Paravetebral(aorticosympathetic) location

312. -Normal anatomy of mediastinal
nervous tissues
-Most peripheral nerve tumors
originate from spinal or
proximal intercostal nerve in
posterior mediastinum
-Thoracic sympathetic trunks and
their associated ganglia are
located on side of vertebral
bodies
-Aortosympathetic paraganglia
are adjacent to sympathetic
chain in posterior mediastinum
whereas aortopulmonary
paraganglia are located along
great vessels

313. 3-Radiographic Features :
a) Plain Radiography
b) CT
c) MRI

314. a) Plain Radiography :
-Well circumscribed rounded mediastinal
mass

316. 29 year old man with posterior mediastinal paraganglioma ,
chest radiograph shows large lobulated mass in left
paraspinal area (arrow)

317. b) CT :
-Mediastinal paragangliomas are seen in as a
mass in a characteristic location in the
paraaortic region of the middle mediastinum or
paravetebral region of the posterior mediastinum
corresponding to major cluster of sympathetic
ganglion cells
-Uncomplicated mediastinal paragangliomas
demonstrate intense contrast enhancement

318. 29 year old man with posterior mediastinal paraganglioma , CT+C
shows hyperenhancing mass with cystic change (arrowhead) in left
posterior mediastinum

319. 29 year old man with posterior mediastinal paraganglioma , CT shows
linear and punctate foci of calcification (arrow) within tumor mass

320. Axial CT+C shows heterogeneous mass between ascending aorta and
pulmonary trunk , there are intratumoral vessels (arrows), which suggest
hypervascularity of tumor , pulmonary trunk is compressed by mass and
invasion is suspected

322. c) MRI :
-Mediastinal paraganglioma shows
enhancement on T1+C with conspicuity of
the lesion hightlighted by flow avoid in the
adjacent mediastinal vessels on spin-echo
sequences

323. Axial T2 fat-suppressed shows heterogeneous high signal intensity in
mass and flow voids (arrows) that reflect high flow in intratumoral
vessels

324. 2-Extrameduallary Hematopoiesis :
a) Causes
b) Radiographic Features

325. a) Causes :
-Is a response to erythropoiesis failure in bone
marrow :
1-Myeloproliferative Disorders :
-CML
-Polycythemia Vera
2-Haemoglobinopathies :
-Sickle cell disease
3-Thalassemia

326. b) Radiographic Features :
-Posterior mediastinal masses , these are
paraspinal masses that may be unilateral or
bilateral and have smooth sharply delineated
often lobulated margins
-Suspect diagnosis if :
1-Multiple bilateral posterior mediastinal masses
2-Cortical bone changes by CT
3-Clinical history of anemia
4-Marked contrast enhancement

327. Left : There are large paraspinal masses (white arrows) with smoothly
marginated lobulated contours , all of the ribs (red arrow) are
expanded and the overall bone density is increased
Right : Large paraspinal masses are seen (white arrows)

328. Large lobulated retrocardiac masses

329. Frontal chest film (a) and scout view (b) show a bulging of the right
paraspinal line, CT scans (c-f) show bilateral soft-tissue paraspinal
masses, representing extramedullary hematopoiesis, in a young
thalassaemic patient

335. 3-Paraspinal Abscess :
a) Causes
b) Radiographic Features

336. a) Causes :
-Infection of the soft tissues surrounding the
spine due to a suppurative bacterial or
mycobacterial infection with phlegmon
formation

337. b) Radiographic Features :
-High signal intensity fluid collections on T2
-Peripheral enhancement in areas of
reactive granulation tissue on post
contrast
-May be associated with intervertebral disc
space infection
-Tubercular abscesses may eventually
calcify

338. PA 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)

339. CT 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

340. PA radiograph shows the right paraspinal line (arrow)

341. Paraspinal abscess , (a) PA chest radiograph shows a mass (arrow) effacing
the left paraspinal line , the lateral wall of the descending aorta is seen as a
separate entity (arrowhead) , (b) CT shows a paraspinal abscess (arrow)
effacing the paraspinal lines , the air soft tissue interface between the lung
and aorta remains intact (arrowhead) , thereby preserving the normal
radiographic appearance of the lateral aortic wall

342. 4-Descending Aortic Aneurysm :
-See before

343. Descending aortic aneurysm , (a) PA chest radiograph shows lateral
displacement of the lateral margin of the descending thoracic aorta
due to an aortic aneurysm (arrowheads) , (b) CT also demonstrates
the aneurysm (arrow)

346. 5-Esophageal Duplication Cyst :
-See Congenital Pulmonary Lesions
6-Neuroenteric Cyst :
-See Congenital Pulmonary Lesions

347. Duplication cyst in a 10-year-old girl with cough, (a) Chest radiograph
shows a round area of increased opacity that deforms the
azygoesophageal recess (arrow), (b) CT+C shows a thin-walled
water-attenuation cyst adjacent to the esophagus (arrow)

348. Esophageal duplication cyst

349. Esophageal duplication cyst

350. Neurenteric cyst in a 30 year old female with flank pain , (a) Chest radiograph shows a
well defined round mass (arrow) in the lower thoracic region , (b- c) Both axial T1 and
coronal T2 show a large mass that is of homogenous high signal intensity in the right
paravertebral region (arrow) , the cyst presumably contains proteinaceous fluid

351. 7-Pancreatic Pseudocyst :
a) Incidence
b) Radiographic Features

352. a) Incidence :
-This follows extension of a pancreatic
pseudocyst in the posterior mediastinum
-This occurs via the esophageal or aortic
hiatus and therefore lies adjacent to the
esophagus
-Most case are seen in adults with clinical
features of a chronic pancreatitis (it can
also occur in children following trauma)

353. b) Radiographic Features :
1-Plain Radiography
2-CT

354. 1-Plain Radiography :
-A space occupying mass in the posterior or
middle mediastinum

355. Initial examination showed an intrathoracic mass overlying the left
margin of the heart (arrowheads) , no interstitial pulmonary edema
was noted ,small pleural effusions are shown

356. 2-CT :
-A thin walled cyst continuous with the
pancreas
-Left sided or bilateral effusions

357. Pancreatic pseudocyst in a 40 year old male with a 3 week history of
chest and epigastric pain , CT+C shows bilateral pleural effusion
and periaortic fluid collection (arrow) displacing the esophagus
(arrow)

358. Pancreatic pseudocyst in a 45-year-old woman with a 2-week history of
dysphagia and chest pain, (a) CT+C shows bilateral pleural effusion and a
thin-walled periaortic cystic lesion that displaces the esophagus (arrow)
anteriorly, (b) Axial T1 shows a low-signal-intensity cyst (arrow)

359. CT+C , a large cystic lesion is compressing the heart ,
predominantly the left ventricle (arrowheads)

360. 8-Bochdalek Hernia :
-See Congenital Pulmonary Lesions
9-Hiatus Hernia :
-See Esophagus

361. Bochdalek Hernia: Axial CT of the lung bases shows abnormal
herniation of abdominal fat contents into the lower posterior left
hemithorax through the left hemidiaphragm (arrows)

362. On a frontal chest radiograph (a), the distal third of the
azygoesophageal recess demonstrates an abnormal contour and
bilateral convexity, lateral chest X-ray (b) demonstrates a
retrocardiac hyperlucency mass consistent with hiatal hernia

363. 10-Lateral Meningocele :
a) Incidence
b) Radiographic Features

364. a) Incidence :
-A rare lesion due to protrusion of the spinal
meninges through an intervertebral
foramen
-Usually asymptomatic
-It is commonly associated with
neurofibromatosis (as neurofibroma)

365. b) Radiographic Features :
1-Plain Radiography
2-CT

366. 1-Plain Radiography :
-A posterior mediastinal mass (often with
pressure deformity on the adjacent bone)
-It is indistinguishable from neurofibroma

367. X Ray of the chest showing meningocele as a mass lesion
‑

368. 2-CT :
-A fluid filled mass (rather than solid)
-Intrathecal contrast medium shows flow into
the lesion

369. Lateral thoracic meningocele in a 37-year-old man with
neurofibromatosis, CT scan shows a low-attenuation mass
protruding from the enlarged left intervertebral foramen

370. Lateral Meningocele in NF

371. MR demonstrates signal intensity identical to CSF