mediastinal masses
TRANSCRIPT
MEDIASTINAL MASSES
BY: joseph soqueña, MD
MEDIASTINAL MASSESStatistically > 60%
ThymomasNeurogenic TumorsBenign CystsLymphadenopathy (LAD)
Children Neurogenic tumors Germ cell tumors Foregut cysts
MEDIASTINAL MASSES
In adults the most common are: Lymphomas LAD Thymomas
Thyroid masses
MEDIASTINAL MASSES
Localizing: mediastinal mass will not contain air
bronchograms.
The margins with the lung will be obtuse.
Mediastinal lines (azygoesophageal recess, anterior and posterior junction lines) will be disrupted.
MEDIASTINAL MASSESLocalizing:
There can be associated spinal, costal or sternal abnormalities.
A lung mass abutts the mediastinal surface and creates acute angles
with the lung, while a mediastinal mass will sit under the surface creating obtuse angles with the lung
MEDIASTINAL MASSES
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.
MEDIASTINAL MASSES
A. Pancoast tumor. B. Thymoma
ANATOMY
ANATOMY
Anatomic divisions:1. anterior (prevascular)2. middle (cardiovascular)3. posterior (postvascular)
Anterior compartmentBoundaries:
Ant – sternumPost – pericardium, aorta, &
brachiocephalic vessels merges superiorly with the
anterior aspect of the thoracic inlet and extends down to the level of the diaphragm
Anterior compartmentContents
thymus, lymph nodes, ascending aorta, pulmonary artery, phrenic nerves and thyroid.
Masses: most common will be of thymic
or lymphnode in origin.
Anterior compartment
The four T's make up the mnemonic for anterior mediastinal masses::
1. Thymus2. Teratoma (germ cell)3. Thyroid4. Terrible Lymphoma
Anterior compartment:Appearance on conventional
radiograph: displaced anterior junction line obliterated cardiophrenic angles obliterated retrosternal space hilum overlay sign effacement/ dense ascending aorta
Anterior compartment
WIDENING OF THE SUPERIOR MEDIASTINUM AND OBLITERATED RETROSTERNAL SPACE
Anterior compartment
Hilum Overlay Sign: hilar vessels are seen through a mediastinal mass
Anterior compartmentThymoma
most common primary neoplasm to occur in the anterior mediastinum
arise from thymic epithelial cells
affects man and women equally
uncommon in children and is diagnosed between ages 40 - 60
may have cystic component and sometimes comprise most of the tumor
Anterior compartmentThymoma
noninvasive (encapsulated) and invasive symptoms are cause by pressure of the
enlarged thymus on the trachea and blood vessels
associated conditions:a. pure red cell aplasiab. myasthenia gravis (most common
paraneoplastic disease asso.)
c. hypogammaglobulinemia
Anterior compartmentThymoma
Thymoma in a 55-year-old woman with recurrent lung cancer. A homogenous mass with convex margin is demonstrated within the thymus. Left lung nodule (white arrow) represents lung cancer recurrence.
Anterior compartment Thymoma
Invasive thymoma. Homogeneous, anterior mediastinal mass extends to the left. Irregular interface suggests extracapsular invasion; lung and pericardial invasion were found at surgery.
Anterior compartment Thymoma
Invasive thymomas. (A) Irregular interface with lung (arrow) suggests pulmonary invasion (surgically proven). (B) Encasement of the aorta and mass protruding into the lung, suggesting invasion.
Anterior compartment Thymoma
Thymoma tends to spread along the pleural surfaces and may extend into the abdomen via the retrocrural space. (A) Small discrete pleural implant (black arrow), visualized to advantage on lung window. (B) Left retrocrural spread (white arrow). (C) Retroperitoneal implant (black short arrow).
Anterior compartment Thymoma
A small thymoma anterior to the heart (marked with the red line)
Anterior compartmentThymoma
WHO Histologic classification: A - a tumor composed of a population of neoplastic
thymic epithelial cells having a spindle/oval shape, lacking nuclear atypia and accompanied by few or no non-neoplastic lymphocytes
AB - tumor in which foci having the features of type A thymoma are admixed with foci rich in nonneoplastic lymphocytes
B1 - tumor resembles the normal functional thymus because it contains large numbers of cells that have an appearance almost indistinguishable from normal thymic cortex with areas resembling thymic medulla
Anterior compartmentThymoma
WHO Histologic classification:B2 - the neoplastic epithelial component of this
tumor type appears as scattered plump cells with vesicular nuclei and distinct nucleoli among a heavy population of nonneoplastic lymphocytes
B3 - is predominantly composed of epithelial cells that have a round or polygonal shape and that exhibit no or mild atypia. The epithelial cells are admixed with a minor component lymphocytes.
C - a thymic tumor exhibiting clear-cut cytologic atypia and a set of cytoarchitectural features no longer specific to the thymus, but rather analogous to those seen in crcinomas of other organs
Anterior compartmentThymoma
Pathologic characteristics: most type A & B are well encapsulated and round or slightly lobulated
usually 5 to 15 cm in diameter
subdivided into numerous lobules by variably thick fibrous band
some may have cystic component
Anterior compartment Thymoma
An encapsulated cystic thymoma.
Anterior compartment Thymoma
MEDIASTINUM: LOCALLY INVASIVE, CIRCUMSCRIBED THYMOMA (MIXED LYMPHOCYTIC AND EPITHELIAL AND MIXED POLYGONAL AND SPINDLE)
Anterior compartmentThymoma
Radiologic Manifestations: most type A & B are situated near the jxn of the heart and great vessels radiographically, they are round or oval, and their margins are usually smooth or lobulated displace the heart and great vessels posteriorly on CT, they are typically located in the region of the thymus anterior to the aortic root and main pulmonary artery & project to one side of the mediastinum
Anterior compartmentThymic Carcinoma (type c)
5 – 15cm in diameter
are often found to invade adjacent tissues at the time of diagnosis
most will show evidence of extension outside the thymus with focal or diffuse
obliteration of the adjacent fat planes.
squamous cell CA- most common histologic type
Anterior compartmentThymic Carcinoma (type c)
Radiologic presentation large ant mediastinal mass with irregular or poorly defined margins.
CT scan presentation: can have a homogenous ST attenuation or heterogenous due to necrosis or hemorrhage calcification is present in 10% of cases Pericardial or pleural involvement and
pleural effusion are frequent findings
.
Anterior compartmentThymic Carcinoma (type c)
Other findings: hilar lymph node enlargement
diaphragmatic elevation suggesting phrenic nerve palsy
lung nodules suggestive of metastases
Anterior compartmentThymic Carcinoma (type c)
Thymic SSC. Large heterogenous mass extending along the pericardium, with probable invasion (arrows). Six weeks following a Chamberlain procedure (left anterior thoracotomy) there is new chest wall invasion, compatible with tumor seeding in the surgical wound.
Anterior compartmentThymic Carcinoma (type c)
High grade thymic carcinoma with mediastinal lymph node enlargement (black arrow) and pleural involvement, including pleural mass (white arrow head) and loculated pleural effusion (white arrow).
Anterior compartmentThymic Carcinoma (type c)
Thymoma. Large mass extending into the right hemithorax, containing punctuate and coarse calcifications. Low attenuation regions suggesting necrosis and/or hemorrhage
Anterior compartmentThymic Lymphoma
2nd most common primary anterior mediastinal mass.
cancer of the lymphatic system
indistinguishable from other solid neoplasm arising w/in the thymus
most commonly involves the anterior mediastinal and hilar nodal group
enlarged spleen displacing the gastric bubble medially in the upper abd.
Portion of the frontal chest film
Anterior compartmentThymic Lymphoma
CT advantages to better characterized and
localized for staging, prognosis and
therapy guidance for trans thoracic or
open biopsy to monitor response to therapy detection of relapse
Anterior compartmentThymic Lymphoma
A, B) Thymic lymphoma. Thymic mass and enlarged mediastinal and right hilar lymph nodes.
Anterior compartmentThymic hyperplasia:
meas: CT thickness = <20 yrs – 1.8cm
>20 yrs – 1.3cm
rare in adults inc in size with normal gross architecture histologic appearance. rebound to atrophy 2nd to chemotherapy or by hypercorticolism
Anterior compartmentCT images of the normal involution of the thymus
A. childhood B. early adulthood C. middle age D. late adulthood
Anterior compartmentThymic hyperplasia:
Thymic hyperplasia in a 29-year-old female. A. Mild diffuse thymic enlargement with biconvex margins. B. CT scan 3 years later demonstrates residual normal thymic tissue.
Anterior compartmentGERM CELL TUMORS
1. TERATOMA most common GCT
consist of one or more types of tissue, usually derived from more than one germ layer
majority are cystic and benign
if solid most likely malignant
Anterior compartmentGERM CELL TUMORS
TERATOMA subdivided into
a. mature – most common form - 8 to 10cm in diameter, often
multicystic- ectodermal elements (epidermis &
skin)b. immature
- same as mature but contain a foci of primitive less well organized tissue resembling seen in fetus
c. teratoma with malignant transformation
- mature tiss + immature tiss and neoplastic tisssue
Anterior compartmentGERM CELL TUMORS
TERATOMASymptoms:
shortness of breath cough sensation of pressure or pain in
the retrosternal area malignant forms may obstruct the
SVC mediastinitis, empyema, fistula
formation, due to rupture of cystic form
Anterior compartmentGERM CELL TUMORS
TERATOMARad features:
localized mass in the anterior compartment close to the origin of the great vessels in the heart
calcification is present in 20%
on CT mature teratoma can have smooth or lobulated margins and may contain one or more cystic areas
Anterior compartmentGERM CELL TUMORS
TERATOMAComplication:
atelectasis and obstructive pneumonitis (airway compression)
pneumonitis (rupture into the lung)
effusion (rupture into the pleural space or pericardium)
Anterior compartmentGERM CELL TUMORS
2. SEMINOMA second most common mediastinal
germ cell tumor
majority are solid, but can have multilocular cystic
component
occurs almost exclusively in men
average age of occurrence is 20-30 y/o
Anterior compartmentGERM CELL TUMORS
SEMINOMARadiographic appearance:
invasion of adjacent structures is uncommon
large masses that project to one or both sides of the mediastinum
homogenous attenuation on CT & only enhances slightly with contrast
Contrast-enhanced axial CT scan shows an ill-defined anterior mediastinal mass with irregular borders that is infiltrating the mediastinal fat. CT-guided needle biopsy revealed a mediastinal seminoma.
Anterior compartmentGERM CELL TUMORS
THYROID TUMORS Multinodular Goiter
- most frequent thyroid tumor- commonly in women in their forties
80% of the tumors arise from a lower pole or the isthmus & extends into the ant or mid mediastinum 20% arise from the post. aspect of thyroid and extend to the post aspect of the mediastinum
Anterior compartmentTHYROID TUMORS
Radiographic appearance: sharply defined, smooth or lobulated
mass that causes displacement and narrowing of the trachea
ant & mid mediastinal mass, displaces the trachea post & lat
post mediastinal mass pushes the trachea ant
the thyroid enhance intensely on CT w/ contrast
focal non enhancing areas of low attenuation as a result of hemorrhage or cyst
Anterior compartmentLIPOMA:
CT scan is usually diagnostic has lower attenuattion than most mediastinal masses does not cause symptoms may have an hourglass appearance, with homogenous fat attenuation surgical excision is curative
Anterior compartmentLIPOMATOSIS:
non-neoplastic
excessive accumulation of fat asso with hypercortisolism,(Cushing’s synd, ectopic adrenocorticotrophic hormone syndrome, long term corticosteroid therapy)
Rad features - smooth, symmetrical widening of the mediastinum - widening usually extends from the thoracic inlet to the hila bilaterally - CT is diagnostic
Anterior compartmentDEVELOPMENTAL ANOMALIES:
1. HEMANGIOMA
can isolated or part of a multifocal hemangiomatous malformation
most are located in the upper portion of the anterior mediastinum
2. Lymphangioma Types
a. cystic hygroma – extends from the neck into the mediastinum, usually occurs in infants
Anterior compartmentDEVELOPMENTAL ANOMALIES:
Lympangiomab. found in adults and located in the lower
anterior mediastinum
sharply defined, smoothly marginated mediastinal mass that displaces adjacent midiastinal structures
on CT – smoothly marginated cystic mass with homogenous water density,
that can either displace or surround adjacent vessels
Anterior compartmentDEVELOPMENTAL ANOMALIES:
3. Mesothelial (pericarial) cyst congenital and result from aberrations in formation of the coelomic cavities.
common in the vicinity of the heart
spherical or oval, thin walled, and often translucent
most are unilocular
Anterior compartmentDEVELOPMENTAL ANOMALIES
Messothelial (pericarial) cystRad findings:
located in the cardiophrenic angles, most commonly in the right
smooth, round and oval 3 – 8 cm in diameter CT – has a water density, smooth,
round, or oval cystic lesion abutting the pericardium
Middle compartment
Contents:1.pericardium and its contents2.aortic arch & proximal great arteries3.central pulmonary arteries & veins4.trachea and main bronchi5 lymph nodes6. hila (considered as extension)
Middle compartmentPresentation on conventional
radiograph1. widened paratracheal stripes.2. AP window mass3. displaced azygoesophageal recess in the right4. mass on posterior trachea5. lateral “doughnut”
Middle compartment
AP chest radiograph showing widening of the azygoesophageal recess on the right. There is an apparent widening of the paravertebral line on the left. On the lateral film the mass is anterior to the spine and therefore is located in the middle mediastinal.
Middle compartment
CT showing the azygoesophageal recess is displaced to the right due to oesophageal varices (blue arrow) and there is also a new interface on the left. This is a patient with cirrhosis of the liver and varices as a result of portal hypertension.
Middle compartment
PA film showing a lobulated paratracheal stripe on the right.On the lateral radiograph there is a density overlying the ascending aorta and filling the retrosternal space.These findings indicate a mass in the anterior aswell as in the middle mediastinum.
Middle compartment
A lobulated mass surrounding the right bronchus creating a 'doughnut' with the bronchus as the hole in the doughnut.
Middle compartmentMasses1. Lymph node enlargement
most middle mediastinal lymph node masses are malignant
malignant causes:- bronchogenic CA- extra thoracic malignancy- leukemia- lymphoma
Middle compartmentLymph node enlargement
benign- sarcoidosis- mycobacterial and fungal- angiofolicular lymph node
hyperplasia (Castleman disease)
- angioimmunoblastic lymphadenopathy
8 (grey) = para-oesophageal9 (brown) = pulmonary ligament nodes10R and 10L (yellow) = right and left hilar11R and 11L (green) = right and left interlobar 12R and 12L (pink) = right and left lobar nodes13R and 13L (pink) = right and left segmental 14R and 14L (pink) = right and left subsegmental Ao = aortic arch, PA = main pulmonary artery,,
1 (red) = highest mediastinal nodes,
2R and 2L (dark blue) = right and left upper paratracheal nodes
3 (pink) = pre-vascular and retrotracheal nodes
4R and 4L (orange) = right and left lower paratracheal
5 (black) = subaortic nodes
6 (red) = para-aortic nodes.
7 (blue) = subcarinal nodes
Middle compartmentLymph node enlargement
Rad appearance: multiple bilateral mediastinal
masses that distorts the lung/mediastinal interface.
round or oval soft tissue masses > 1cm in their short axis diameter
if solitary, tends to be elongated and lobulated rather spherical
calcifications can sometimes be seen
Middle compartment
Lymph node enlargement Rad appearance:
CT scan is more sensitive in detecting nodal calcification
CT is unable to distinguish between benign inflamatory nodes and those involved by malignancy.
Middle compartmentMesothelial cysts:1. Congenital Bronchogenic Cyst
result from anomalous budding of the tracheobronchial tree.
walls should be lined with respiratory epithelium
arise w/in the mediastinum in the vicinity of the tracheal carina
Middle compartmentCongenital Bronchogenic Cyst
frequently seen in the subcarinal or right paratracheal space
sometimes maybe seen in hilum, posterior mediastinum, periesophageal region
single smooth, round or elliptic mass
CT is the method of choice for diagnosis
Middle compartment
Congenital Bronchogenic Cyst Benign – well defined thin walled
mass of fluid density that fails to enhance with contrast.
- some are lobulated
Middle compartment
(Mesothelial) Pericardial Cyst: arise from the parietal pericardium
most are 3-8cm in diameter
commonly in the anterior cardiophrenic angles
more common in the right than in the left
usually present as a unilocullar cystic mass on CT scan
Posterior compartmentContents
descending aorta azygous and hemiazygous vein thoracic duct intercostal and autonomic nerves
Conventional radiographs Cervicothoracic Sign Widening of the paravertebral stripes
Posterior compartment
• Cervicothoracic sign - the anterior mediastinum stops at the level of the superior clavicle.Therefore, when a mass extends above the superior clavicle, it is located either in the neck or in the posterior mediastinum.When lung tissue comes between the mass and the neck, the mass is probably in the posterior mediastinum.
Posterior compartment
There is widening of the paravertebral stripes on both the left and the right on the this PA radiograph.On the lateral radiograph there is a severely narrowed disc space.
Posterior compartment most are neurogenic in nature
- from the sympathetic ganglia (eg neuroblastoma)
- from the nerve roots (eg schwannoma or
neurofibroma). lymphadenopathy neuroenteric cysts, schwannomas or meningoceles.
Posterior compartment1. Neurogenic Tumors.
Classification:a. neurofibroma, schwanoma
(arising from the intercostal nerves)
b. ganglioneuroma, ganglioneuroblastoma, neuroblastoma (sympathetic ganlia)
c. chemodectoma, pheochromocytoma (paraganlionic cells) neuroblastoma & ganlioneuroma – common in children neurofibroma & schwanoma – affects adult more frequently
Posterior compartmentNeurogenic Tumors.
Rad appearance: intercostal nerve tumors appear
as round or oval paravertebral soft tis masses
CT – smooth or lobulated paraspinal soft tissue mass w/c may erode adjacent vertebra or rib
Posterior compartmentEnteric/Neuroenteric cyst
fluid filled masses lined by enteric epithelium
esophageal cyst – arise intramurarly or immediately adjacent to
the esop.
neuroenteric cyst – persistent communication with the spinal canal and asso with congenital defects of the T-spine.
Fluid containing masses
Thymoma Teratoma Pericardial Cyst Foregut Duplication Meningocoele Neuroenteric Cyst Cystic Lymphadenopathy Lymphangioma
Fat containing masses
Thymolipoma
Teratoma (Germ cell tumors)
Esophageal lipoma
Fat deposition
Lipoma
Lipoblastoma
Liposarcoma
Extramedullary hematopoiesis
Enhancing masses
Hyperenhancing lymph nodes
Thyroid tissue
Paragangliomas
Hemangiomas
Vascular Etiologies
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MEDIASTINAL MASSES
ANATOMY
• anterior mediastinum (1) • middle mediastinum (2) • posterior mediastinum (3)
ANATOMYSuperior Med.
bounded by:
sup thoracic aperture (thoracic inlet) inf line from sternal angle ant manubrium post 1st 4
thoracic vert.
ANATOMY1.Anterior
ant body of sternumpost fibrous pericardium
contents: thymus branches of the internal mammary
artery and vein lymphnode inferior sternopericardial ligament fats
ANATOMY2. Middle between the anterior and
posterior subdivision of the mediastinumcontents:
the pericardium and its contents ascending & transverse portion
of the aorta sup & inf vena cava bifurcation of the trachea and
two bronchi pulm artery and veins phrenic nerves and the lymphatic
glands
ANATOMY3. Posterior
ant. By the pericardium, laterally by the mediastinal pleura and posteriorly by thoracic vertebrae
Contents: descending thoracic aortaesophagus thoracic duct, azygos,
7hemiazygos veins autonomic nerves, fats
&lymohnodes
Mediastinal Masses
ANATOMYSuperior mediastinum:
content: aortic arch, brachiocephalic arter,
left common carotid and the left subclavian.
innominate veins, and left and right brachiocephalic veins
vagus nerve, cardiac nerve, phrenic nerve, & left recurrent laryngeal nerve
trachea, esophagus, thoracic duct, thymus and some lymph glands
ANATOMY
MEDIASTINAL DIVISION1. Superior mediastinum
2. Inferior mediastinuma. anteriorb. middlec. posterior
ANATOMYInferior mediastinum contents:
Ant