4. Introduction
Mediastinal masses
span a wide
histopathological and
radiological spectrum
benign or malignant
primary or secondary
Affect people of all age
groups,
more common in young
and middle-aged adults
Most are benign &
usually asymptomatic
Precise dx is difficult to
w/o histopathologic
examination
5. Clin.presentation
• Majority-
asymptomatic
• detected incidentally
• Sign and sxs vary
depending on:
o The age of the patient
o Nature and location of
the mass
o Presence or absence
of infection
o Biochemical products
o Associated disease
states
9. Cont…
CT(Contrast)
• most useful in
localizing the origin
• to evaluate the extent
• to guide biopsy and
follow Rx response
MRI
• better soft tissue cxn
than CT
• delineating the
composition of the
mass
• Very useful in imaging
neurogenic tumors
10. Cont…
NUCLEAR MEDICINE
• PET & PET-CT-
evaluation of
mediastinal LN
involvement in lung
Ca and lymphoma
• PET-CT…commonly
used to evaluate Rx
response
• 123I or 131I-presence of
thyroid tissue within
the mediastinum
• Examination of
neuroendocrine
tumors and
pheochromocytomas
12. IMAGING FEATURES
THYROID MASSES
• 3%-17% of goiters extend
into the thorax
• Rounded or irregular,
well-defined areas of
calcification - benign
areas
• Amorphous cloud-like
calcification-seen within
carcinomas
• tracheal narrowing or
deviation of the trachea
depending on the location
of the mass
13. Cont…
• CT features of
mediastinal goiters
High attenuation on a non-
contrast exam (high I2 )
Intense and prolonged
enhancement ff contrast
enhancement
Continuity of the mass with
the cervical thyroid gland
Calcifications and cystic
regions resulting in foci of
heterogeneous attenuation
14. …
THYMIC MASSES
1. Thymomas
• benign or low-grade
malignant tumors of thymic
epithelium.
• demonstrates an abnormal
contour or widening of the
mediastinum on PA
radiographs
• opacity in the anterior clear
space on the lateral
radiograph
• homogeneous density and
uniform enhancement on
contrast CT
16. Cont…
• On MRI-low T1 signal
intensity,relatively high
T2 signal intensity
• MRI is superior to CT
for defining the
invasion of
contiguous structures
such as the pleura and
pericardium
17. Thymic Carcinomas
• poor prognosis despite
treatment with surgery
and radiotherapy
• typically large,
heterogeneous masses,
with areas of necrosis
and calcification and
evidence of invasion of
adjacent structures
• On MRI-intermediate
signal intensity on T1 and
high signal intensity on
T2
18. …
. Thymic Hyperplasia-
increase in size with
normal gross and
histologic appearance
• commonly occurs ff
atrophy due to
o stress
o steroid therapy or
o chemotherapy
Axial CT image demonstrating a well-defined,
homogeneous appearing mass within the anterior
mediastinum
suggestive of thymic hyperplasia (arrow).
19. …
4.Thymic Cyst
• uncommon,1% of all
mediastinal masses
• On CXR can’t be
differentiated from other
thymic masses.
• On CT…well-
defined,water
attenuation masses
• On MR…typical cxc of
fluid with low T1 and
high T2 intensity
20. …
PARATHYROID TUMORS
• rare cause of an anterior
mediastinal mass
• most commonly located in
or around the thymus
• small and almost invisible
on plain radiographs
• 99mTc scintigraphy- most
sensitive imaging
• CT-small nodules,minimal
or no enhancement
• MRI- isointense on T1-
weighted and hyperintense
on T2
21. GCT of the MEDIASTINUM
• derived from primitive
germ-cell elements
• most common
extragonadal site is
the mediastinum
• 60% arises in the
anterior
mediastinum
22. Cont…
1.TERATOMAS
• Mature teratomas are
found at all ages
• usually asymptomatic
and diagnosed
incidentally on CXR or
CT
• but may be
symptomatic if they
compress the bronchial
tree or SVC ,or if they
rupture
23. Teratoma cont…
o well-defined, rounded or
lobulated mass, localized
to the anterior mediastinum
o On CT-combinations of fat,
fluid, soft tissue
components, and
calcification may be seen
o presence of fat is a very
helpful diagnostic feature
favoring mature (benign)
cystic teratoma
o On MRI…Fat - fluid levels
are virtually diagnostic of
teratomas
24. …
2. SEMINOMAS
• occurs almost
exclusively in males(2-4
decades)
• Symptoms-usually due
to mass effect on
adjacent structures
• On CT and MR -
homogenous
attenuation and signal
intensity
25. NSGCT
• CT -lobular, asymmetrical
mass
• obliteration of mediastinal
fat
• multiple areas of contrast
enhancement
interspersed with areas of
decreased attenuation
due to necrosis and
hemorrhage
• On MRI-heterogeneous
intensities
26. LYMPHOMA
• common cause of
mediastinal
adenopathy
• prevascular and
paratracheal nodes-
most frequently
involved(Hodgkin’s
disease, particularly)
27. …
BRONCHOGENIC CYSTS
• usually asymptomatic
solitary mass
• may compress surrounding
structures and cause
symptoms
• The most common location
is subcarinal
• CXR- round mass in the
middle mediastinum
abutting the carina or main
bronchi
• CT… thin-walled mass, with
contents measuring simple
fluid attenuation
28. …
NEUROGENIC TUMORS
• most common tumors
in the posterior
mediastinum
• Most tumors in adults
are benign and are
discovered as
asymptomatic masses
on chest radiographs
• The best modality for
imaging these tumors is
MRI
29. SERUM MARKERS
(in 10 mediastinal GCT)
1.AFP
• major fetal serum protein
• normally produced during
gestation by fetal
liver,GIT and the yolk sac
• AFP…present in
embryonal carcinoma
and in yolk sac tumors
• never present in pure
seminomas or
choriocarcinomas
30. 2.β-HCG
• elevated in the
majority of
choriocarcinoma and
• in10% of patients
with seminomas
31. …
3.LDH
• its specificity for GCTs is
extremely poor.
• But for monitoring Rx
response and recurrence
• (predicts relapse-free
survival, and overall
survival)
• Therefore, in patients with
GCTs,evaluation of LDH
levels, together with
levels of AFP and β-HCG,
is strongly
recommended
32. Dxtic Non-surgical Biopsies
• 60% anterior
mediastinal masses
treated non-surgically
• CT-guided needle
biopsy,
• EBUS- and EUS-
guided FNA, and
core-needle biopsy
• FNA + core needle
biopsy = 98%acc.
• Vs 79% for each
independently
33. Invasive Ix
• Surgical approaches
for Dx
o anterior
mediastinotomy-
• for large masses in the
anterior mediastinum
o Cervical
mediastinoscopy-
• lesions located in the
superior-middle
mediastinum
o VATS-
• large masses protruding
in the pleural cavity
34. Surgical Approaches
• For complete tumor
removal, larger incisions
must be used.
• The two most common
incisions:
median sternotomy (full or
partial) and
Thoracotomy
• The most common
thoracotomy incision for
mediastinal exposure :
Clamshell incision.
35. …
• TECHNIQUE FOR FULL
STERNOTOMY
• Supine
• standard midline incision …
suprasternal notch to a point just
below the xiphoid process
• Subcutaneous tissue dissection…
electrocautery
• two chest tubes are generally
used to drain the mediastinum.
• If the pleura has been entered,
one of the chest tubes is placed in
that pleural space
• sternum is reapproximated using
interrupted sutures …no. 5 or 6
wire
• subcutaneous tissue and fascia
can be closed in layers
36. …
• COMPLICATIONS
• Rare, <3%
• mediastinitis after
sternotomy…1% to 2%
• Delayed complications
Costochondral
separation,
occult rib fractures
chronic osteomyelitis of
the sternum
rib cartilage necrosis
sternal nonunion
sternal wire erosion
• Advantages of
sternotomy
– speed of opening and
closing
– the sparing of major
thoracic muscles
– Relative reduced
postoperative pain
• Main disadvantages
– limited exposure of the
posterolateral
compartment
– sternal infection
37. • Thoracotomy (muscle
sparing lateral or
posterolateral)
– the most common
approach in general
thoracic surgery
– lung resections
– esophageal lesions
– posterior mediastinal
and paravertebral sulcus
tumors
38. Cont…
• TECHNIQUE
• lateral decubitus position
• Incision just below the tip of the
scapula…down with the electrocautery
through the subcutaneous tissue to the
fascia of the serratus anterior and
beyond the border of the latissimus dorsi
• mobilize the latissimus dorsi posteriorly,
split the serratus anterior in the direction
of its fibers and retract them away from
the intercostal space to be entered
• fourth intercostal space…usual entry
point for exposure to the anterior
mediastinum
• For higher exposure… axillary
thoracotomy
