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Nov 12, 2013 (3 years and 11 months ago)

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NHL



Involves the thorax in approximately
40
%
of patients at
presentation.




50
%
of patients with NHL and
intrathoracic

disease have
mediastinal

nodal involvement, only
10
%

of NHL patients have
disease that is limited to the
mediastinum
.




lymphoblastic lymphoma and diffuse large B
-
cell lymphoma
are the most common type that present with
mediastinal

masses




Lymphoma involving a single
mediastinal

or
hilar

nodal group
is much more common in NHL than in Hodgkin disease.




NHL most commonly involves
middle

mediastinal

and
hilar

lymph nodes;




J
uxtaphrenic

and posterior
mediastinal

nodal involvement is
uncommon but is seen almost exclusively in NHL
.


Calcification in untreated lymphoma is
extremely uncommon

presence within an anterior
mediastinal

mass
should suggest another diagnosis.



clue to the diagnosis:



Involvement of other lymph nodes in the
mediastinum

or
hila





E
nlarged spleen
.


Central necrosis, seen in
20
%
of patients, has no prognostic

significance




Parenchymal

involvement
is usually the result of direct
extranodal

extension of a tumor from
hilar

nodes along the
bronchovascular

lymphatics
;




On MR, untreated lymphoma appears as a mass of uniform
low signal intensity on T
1
WIs and uniform high signal intensity or
intermixed areas of low and high signal intensity on T
2
WIs.

:



low signal intensity on T
2
WIs
of untreated patients

foci of fibrotic tissue in nodular
sclerosing

Hodgkin disease
.


Monitor the response of lymphoma to
therapy:

CT, MR, gallium scintigraphy, (FDG) PET



Assess tumor regression and detect relapse :


CT




The appearance of high
-
signal
-
intensity
regions on
T
2
WIs

more than
6
months after
treatment should suggest recurrence.

Germ cell
neoplasms
:



T
eratoma
,
seminoma
,
choriocarcinoma
,
endodermal

sinus tumor, and
embryonal

cell
carcinoma



Distinguishing primary from metastasis:

presence of retroperitoneal lymph node
involvement in metastatic
gonadal

tumors

Majority in the
anterior

mediastinum
,


Up to
10
% in the
posterior

mediastinum
.


The
most common

benign
mediastinal

germ cell
neoplasm is
teratoma
(
60
% to
70
%)




Teratomas

may be cystic or solid




Most common type of
teratoma

in the
mediastinum


Cystic or mature
teratoma




Solid
teratomas

are usually malignant.




Most germ cell
neoplasms

:third or fourth decade of
life




B
enign tumors female/male,
60
%/
40
%),




M
alignant
tumors


almost in men
.

Seminoma

is the most common
malignant germ cell neoplasm,
accounting for
30
%
of these tumors.

Middle
Mediastinal

Masses

Lymph Node Enlargement:


Most
middle
mediastinal

lymph node masses
are
malignant




Benign causes of middle
mediastinal

lymph
node enlargement :

sarcoidosis
,
mycobacterial

and fungal infection,
angiofollicular

lymph node hyperplasia
(
Castleman

disease), and
angioimmunoblastic

lymphadenopathy


Density of
Mediastinal

Nodes on
CT

lymphoma



Nodal enlargement is bilateral but asymmetric.




Nodular sclerosing Hodgkin disease commonly
results in lymph node enlargement, predominantly
within the anterior mediastinum and thymus.




Isolated posterior nodal enlargement is usually seen
only in patients with NHL


Leukemia (T
-
lymphocytic )




The lymph node enlargement is usually confined to
the middle mediastinal and hilar nodes.

.


The
most common
source of
metastases to middle
mediastinal

nodes is
bronchogenic

carcinoma




Lymph node enlargement is often
unilateral on the side of the visible
pulmonary or
hilar

abnormality.
Paratracheal

and
aorticopulmonary

nodes are most commonly involved

sarcoidosis



Mediastinal

lymph node enlargement occurring in
60
% to
90
%
with
sarcoidosis



Nodal enlargement is typically bilateral and symmetric



I
nvolves the
hila

as well as the
mediastinum


(differentiation of
sarcoidosis

from lymphoma and metastatic
disease)



In
sarcoidosis
, the enlarged nodes produce a
lobulated

appearance




Enlarged nodes do not coalesce(in contrast to lymphoma
and nodal metastases)


M
ost

commonly infections
can cause
mediastinal

nodal enlargement:

histoplasmosis
,
coccidioidomycosis
,
cryptococcosis
,
and tuberculosis


T
hese

patients have
parenchymal

opacities on chest
radiographs, but isolated lymph node enlargement
may be seen, particularly in children and young
adults.




Other bacterial infections
cause
mediastinal

nodal
enlargement :anthrax, bubonic plague, and tularemia

Foregut and mesothelial cysts:


Asymptomatic masses on routine chest radiographs in
young adults
80
% to
90
%




May become secondary infected or hemorrhagic




A
rise within the mediastinum in the vicinity of the
tracheal carina

:



on frontal chest radiographs


Soft tissue masses in the
subcarinal

or
right
paratracheal
space;

Less commonly involve the hilum, posterior
mediastinum, and periesophageal region

Pericardial cyst
s



Arise from the parietal pericardium




Most
often arise in the anterior
cardiophrenic

angles




Right
-
sided lesions being twice as common as
left
-
sided lesions;




Approximately
20
%

arise more superiorly
within the mediastinum

Neurogenic

Lesions

:

Rarely, a
neurofibroma

arising from the
phrenic

nerve may present as a middle
mediastinal

juxtacardiac

mass.


Posterior
Mediastinal

Masses

Neurogenic

Tumors

(
1
) Tumors

arising from
intercostal

nerves
(
neurofibroma
,
schwannoma
);

(
2
)
Sympathetic ganglia
(
ganglioneuroma
,
ganglioneuroblastoma
, and
neuroblastoma
);

(
3
)
P
araganglionic

cells
(
chemodectoma
,

pheochromocytoma
).



Neuroblastoma

and
ganglioneuroma

:most
common in
children




neurofibroma

and
schwannoma

:more frequently
in
adults

Multiple
neurofibroma

and
schwannoma

in the
mediastinum
,
particularly bilateral are virtually
diagnostic of
neurofibromatosis


Radiographically
:
round or oval
paravertebral

soft tissue
masses.




CT
: smooth or
lobulated

paraspinal

soft tissue mass, may
erode the adjacent vertebral body or rib.


Extension from the
paravertebral

space into the spinal canal
via an enlarged
intervertebral

foramen is characteristic of a
neurofibroma
.




MR

is the modality of choice for imaging a suspected
neurofibroma




sympathetic ganglia tumors
present as elongated, vertically
oriented
paravertebral

soft tissue masses with a broad area of
contact with the posterior
mediastinum





These findings may help distinguish these lesions from
neurofibromas
, which usually maintain an acute angle with
the vertebral column and posterior
mediastinum

and therefore
tend to show sharp

superior and inferior margins on lateral
chest radiographs





Calcification,
seen in up to
25
%
of cases.

Neurofibroma

Ganglioneuroma

Thanks for your attention

Thanks for your attention