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B&H Mediastinum and Hila 367-395
Terms in this set (70)
differential for thoracic inlet masses?
thyroid masse (in particular the confl uence of the right
brachiocephalic and right subclavian arteries),
lymphomatous nodes, and
difference between tortuos arteries and actual masses
-thoracic inlet masses that are posterior or paravertebral in location, which are sharply outlined by apical
lung which extends higher posteriorly than anteriorly. This
fi nding is termed the "thoracic inlet" or "cervicothoracic"
sign and helps localize thoracic inlet masses, thereby suggesting
the etiology of such lesions
-Tortuous arterial structures
may be identified by the presence of atherosclerotic calcification
within their walls and can often be seen on a lateral chest
radiograph as a "mass" projecting posterior to the tracheal air
column which is sharply outlined posteriorly
a tortuous vessel is usually
associated with tracheal deviation toward the side of the mass,
whereas most goiters and other inlet masses displace the trachea
2% of pple have the parathyroids fail to separate from the thymus so they descend with the thymus to the ant mediastinum. when neck imaging is negative for hyperparathyroidism, NM scan of chest can reveal ectopic parathyroid tissue in ant sup mediastinum attached to thymus
Drop metastases to dependent portions of the pleural space are a recognized route of spread of thymoma that has invaded the pleura. Extrathoracic metastases are rare, although transdiaphragmatic spread of a pleural tumor into
the retroperitoneum has been described. For these reasons, it
is important to image the entire thorax and upper abdomen in
any patient with suspected invasive disease.
congenital: remnants of the thymopharyngeal duct and contain thin or gelatinous fluid.
Acquired: multilocular thymic cysts are postinfl ammatory in nature and have been associated with AIDS, prior radiation or surgery, and autoimmune conditions such as Sjögren syndrome, myasthenia gravis, and aplastic anemia.
Radiology: Well defined anterior mediastinal mass
is a rare, benign thymic neoplasm that consists
primarily of fat with intermixed rests of normal thymic tissue. These masses are asymptomatic and therefore are typically large when first detected. Chest radiographs show a large
anterior mediastinal mass that, because of its pliable nature, tends to envelope the heart and diaphragm. CT demonstrates a fatty mass with interspersed soft tissue densities. Resection is curative.
-Large, locally invasive anterior mediastinal mass in patient with Cushing syndrome or MEN type 1
-50% encapsulated, most are well circumscribed
± invasion of mediastinal fat or adjacent vascular structures
-Metastases: Regional lymph nodes, bones, and adrenal glands
-CECT is imaging modality of choice for evaluating suspected thymic lesions
either Hodgkin disease or non-Hodgkin
lymphoma (NHL)—is the most common primary mediastinal neoplasm in adults
NHL and HL findings
mediastinum is the most frequent site of a localized nodal mass
in patients with Hodgkin disease, particularly those with the
nodular sclerosing type . Isolated enlargement of
mediastinal or hilar nodes outside the anterior mediastinum
should suggest an alternative diagnosis
Germ cell neoplasms
which include teratoma, seminoma,
choriocarcinoma, endodermal sinus tumor, and embryonal cell carcinoma, arise from collections of primitive germ cells that arrest in the anterior mediastinum on their journey to the
gonads during embryologic development. Since they are histologically indistinguishable from germ cell tumors arising in the testes and ovaries, the diagnosis of a primary malignant mediastinal germ cell neoplasm requires exclusion of a primary gonadal tumor as a source of mediastinal metastases.
A key in distinguishing primary from metastatic mediastinal germ cell neoplasm is the presence of retroperitoneal lymph node involvement in metastatic gonadal tumors.
dermoid cyst vs teratoma
In contrast to a dermoid cyst, which is an ovarian
neoplasm containing only elements derived from the ectodermal germinal layer, a cystic teratoma of the mediastinum commonly contains tissues of ectodermal, mesodermal, and
endodermal origins. For this reason, it is inaccurate to use the term "dermoid cyst" to describe cystic mediastinal germ cell neoplasms
radiographic appearance of thymoma
Anterior mediastinal mass with well-defined, smooth or lobular borders; typically unilateral
Invasive thymoma: Irregular borders, elevated ipsilateral hemidiaphragm, pleural nodules
Prevascular, spherical/ovoid, unilateral soft tissue mass
-Smooth or lobular borders
-Low attenuation foci from necrosis or cystic change Typically no lymphadenopathy
-Invasive thymoma: Local invasion, pleural nodules
Large, lobular anterior mediastinal mass
Large, lobular, mildly enhancing prevascular mediastinal soft tissue mass
Rare cysts or calcification
Mass effect on adjacent mediastinal structures
Homogeneous prevascular mediastinal mass
T2 hypointense, T1 C+ enhancing septa
ned mass of uniform fatty attenuation (under -50 . The
presence of soft tissue elements should raise the possibility of
a thymolipoma or liposarcoma
associated with the syndrome of hereditary
A pathognomonic sign on chest
radiographs is the recognition of phleboliths within a smooth
or lobulated soft tissue mass
Well-defined mediastinal soft tissue mass with central, peripheral, or mixed enhancement
Identification of phleboliths in 30%
Heterogeneous signal intensity on T1WI
Hyperintense on T2WI
T2WI FS high sensitivity for fat
Insensitive for low signal intensity phleboliths
Image-guided needle biopsy is rarely diagnostic
differential for anterior medastinal mass?
differential diagnosis of middle mediastinal lymph node masses
middle mediastinal lymph node masses are malignant, representing
metastases from bronchogenic carcinoma ( Fig. 13.10 ),
extrathoracic malignancy, or lymphoma
benign causes of middle mediastinal lymph node enlargement
mycobacterial tuberculosis and fungal infection(histoplasmosis, cocidioidomycossis,cryptococcosis and tuberculosis)
node hyperplasia (Castleman disease), and angioimmunoblastic
mediastinal mass on cxr?
multiple bilateral mediastinal masses that distort
the lung/mediastinal interface is relatively specifi c for lymph
appearance of lymph node masses
Solitary masses resulting from lymph node
enlargement tend to be elongated and lobulated rather than
spherical, since usually more than a single node in a vertical
chain of nodes is involved
Lymph node map by the International Association for the Staging
of Lung Cancer
location of lymph node enlargement in leukemia?
The lymph node
enlargement is usually confi ned to the middle mediastinal and
The most common source of metastases to middle mediastinal
difference in lymph node enlargement with sarcoidosis
Systemic chronic granulomatous disease characterized by noncaseating granulomas in multiple organs
Lung and mediastinum involved in over 90% of cases
Bilateral hilar lymphadenopathy and right paratracheal lymphadenopathy in up to 95% of patients
Bilateral perilymphatic micronodules (75-90%)
Pulmonary nodules and masses (20%)
Solitary nodule or mass (rare)
Alveolar opacities (10-20%)
Ground-glass opacities (40%)
Pulmonary fibrosis (20%)
Upper lobe-predominant reticular opacities, traction bronchiectasis, architectural distortion, volume loss
appearance of Angiofollicular lymph node hyperplasia (Castleman disease)
is characterized by enlargement of hilar and mediastinal lymph nodes, predominantly in the middle and posterior mediastinal
there is replacement of normal nodal architecture with multiple
germinal centers and multiple small vessels with hyalinized walls
that course perpendicularly toward the germinal centers to give a characteristic "lollipop" appearance on light microscopy.
The vascular nature of these masses accounts for the intense
enhancement seen on contrast-enhanced CT or angiography.
Calcifi cation within these masses has been described. These
lesions are cured by resection.
-Systemic lymphoproliferation associated with immunodeficiency
- Enlarged mediastinal & hilar lymph nodes +/- pulmonary involvement
Nodes may demonstrate avid enhancement
Pleural effusions present in 40%
Congenital bronchogenic cysts
result from anomalous budding
of the tracheobronchial tree during development.
-may produce mass effect on esophagus and trachea
-may become infected
Middle-posterior mediastinal mass
Sharply marginated spherical soft tissue lesion
Majority in middle-posterior mediastinum (80%)
Well-defined, unilocular, spherical cyst
Thin wall; may exhibit enhancement, calcification
Variable attenuation ranging from fluid to soft tissue, may contain milk of calcium
No enhancement of cyst contents
Variable signal on T1WI
High signal on T2WI, parallels that of CSF
what are pericardial cysts?
arise from the parietal pericardium and
contain clear serous fl uid surrounded by a layer of mesothelial
appearance of pericardial cysts?
CT typically shows a unilocular
cystic mass adjacent to the heart;
Homogeneous water attenuation
Homogeneous high signal intensity on T2WI
Parallels signal intensity of CSF
Modality of choice for evaluation of pericardium
Differentiation of solid from cystic masses
classification of Posterior mediastinal masses
arising from neural elements?(3 classes?)
1) tumors arising
from intercostal nerves (neurofibroma, schwannoma)
sympathetic ganglia (ganglioneuroma,ganglioneuroblastoma,
paraganglionic cells (chemodectoma,
age distribution of neurogenic tumors in kids vs adults?
Neuroblastoma and ganglioneuroma
are most common in children, whereas neurofi broma and
schwannoma affect adults more frequently.
similarity and differences between schwannoma and neurofibroma?
While neurofi broma is an encapsulated tumor that contains
interspersed neurons, schwannoma is not encapsulated and
contains no neuronal elements( neural sheath tumor). Both tumors are more common
in patients with neurofi bromatosis. Multiple lesions in
the mediastinum, particularly bilateral apicoposterior masses,
are virtually diagnostic of neurofi bromatosis.
Distal brachial plexus root or trunk
Cervical sensory nerve
appearance of intercostal nerve tumors?
Radiographically, intercostal nerve tumors appear as round
or oval paravertebral soft tissue masses. CT shows a smooth
or lobulated paraspinal soft tissue mass, which may erode the
adjacent vertebral body or rib.
Well-delineated, solitary, fusiform mass
Isodense to hypodense mass
MR: Modality of choice for presurgical evaluation
Contrast-enhanced images critical
Large schwannomas often have cystic component
US: Hypoechoic mass with posterior acoustic enhancement
Marked hypervascularity on color Doppler
demonstration of tumor
extension from the paravertebral space into the spinal canal
via an enlarged intervertebral foramen is characteristic of a
"dumbbell" neurofi broma.
appearance of sympathetic ganglia tumors?
vertically oriented paravertebral soft tissue masses with a broad
area of contact with the posterior mediastinum (Figs. 13.18 ,
13.19 ). These fi ndings may help distinguish these lesions from
neurofi bromas, 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. Large masses may erode vertebral bodies or ribs
lab tests seen in sympathetic ganglia tumors?
Because these tumors
often produce catecholamines, urinary levels of vanillylmandelic
acid or metanephrines, which are byproducts of catecholamine
metabolism, may be elevated
location of parangliomas?
paraganglia of the middle mediastinum or the aorticosympathetic
ganglia of the posterior mediastinum. They are
divided into nonfunctioning neoplasms (chemo-dectomas),
which occur almost exclusively in or about the aortopulmonary
window, and functioning neoplasms (pheochromocytomas),
which are found in the posterior sympathetic chain or
in or about the heart or pericardium
how can u distinguish radiographically between functioning and non-functioning paragangliomas?
meta-iodobenzylguanidine scanning is diagnostic in functioning
clinical presentation of paragangliomas?
most patients have hypertension and biochemical evidence
of excess catecholamine production
differential for esophageal wall mass? 5
diverticula and lipoma
cxr findings in esophageal carcinoma?
abnormal azygoesophageal interface,
widening of the mediastinum (resulting from the tumor itself
or a dilated esophagus proximal to the obstructing lesion),
abnormal thickening of the tracheoesophageal stripe, and
tracheal deviation and compression
enteric cyst from wall of esophagus or adjacent to it that has a persistent communication with the spinal canal (canal of Kovalevski) and is associated with
congenital defects of the thoracic spine (anterior spina bifi da,
hemivertebrae, or butterfl y vertebrae)
Esophageal Duplication Cyst?
common primary sites of thoracic spinal metastases? 3
Bronchogenic, breast, or renal cell carcinoma
infectious spobdilitis vs a neoplastic process?
extramedullary hematopoiesis appearance?
expansion of the medullary space and cyst formation
within long bones, ribs, and vertebral bodies, with associated
lobulated paraspinal soft tissue masses. These masses, which
represent hyperplastic bone marrow that has extruded from
the vertebral bodies and posterior ribs, are typically seen in
the lower thoracic and upper lumbar region
lateral thoracic meningocele? association?
herniation of the spinal meninges through an intervertebral
foramen, resulting in a paravertebral soft tissue mass
There is a high association
between lateral thoracic meningoceles and neurofi bromatosis
diagnostic clues of Lateral thoracic meningoceles
Additional clues to the diagnosis include rib
erosion, enlargement of the adjacent neural foramen, vertebral
anomalies, or kyphoscoliosis
Acute mediastinitis? and causes
bacterial infection that
most often develops following esophageal perforation or is
a complication of cardiothoracic or esophageal surgerypenetrating chest trauma, esophageal carcinoma,
foreign body or corrosive ingestion, or vomiting
esophageal perforation following prolonged vomiting
cxr appearance of beorhaave?
The most common chest radiographic fi ndings are widening
of the superior mediastinum in 66% of patients and pleural
effusion in 50% of patients. Specifi c fi ndings such as mediastinal
air or air-fl uid levels are less common. When mediastinitis
occurs in association with Boerhaave syndrome, pneumoperitoneum
and left hydropneumothorax may be seen.
Chronic Sclerosing (Fibrosing) Mediastinitis? and cause?
of chronic sclerosing mediastinitis are chronic infl ammatory
changes and mediastinal fi brosis. The most common
cause of this rare condition is granulomatous infection, usually
secondary to Histoplasma capsulatum
radiation therapy, and drugs (methysergide) are less common
causes. Idiopathic mediastinal fi brosis
sequelae of Chronic Sclerosing (Fibrosing) Mediastinitis? and cause?
-obstruction of the central pulmonary veins, which produces
pulmonary edema that may mimic severe mitral stenosis
-obstructive pneumonitis from obstruction of the tracheobronchal tree
-Dysphagia or hematemesis can be seen with
appearance of chronic mediastinitis on cxr and CT?
The most common fi nding noted on chest radiographs is
asymmetric lobulated widening of the upper mediastinum,
most often on the right. When the process is secondary to
granulomatous infection, enlarged calcifi ed lymph nodes
may be seen. Narrowing of the tracheobronchial tree may be
nodes with calcifi cation are the most common fi nding.The fi brotic infi ltration of the mediastinal fat that is
characteristic of this condition is seen as abnormal soft tissue
density replacing the normal mediastinal fat with obliteration
of the normal mediastinal interfaces. CT delineates the degree
of involvement of the mediastinal vessels, trachea, and central
bronchi. In patients with signifi cant SVC involvement, collateral
venous channels within the mediastinum and chest wall
are well demonstrated
mediastinal hemorrhage findings?
focal or diffuse widening of the mediastinum
that obscures the normal mediastinal contours ( 13 ). In
mediastinal hemorrhage, the mediastinum develops a fl at or
slightly convex outward contour, unlike the round, lobulated or irregular contour seen with enlarged lymph nodes or a localized
Blood extending from the mediastinum
into the pleural or extrapleural space produces a free-fl owing
effusion or a loculated extrapleural collection, respectively
mediastinal lipomatosis and causes?
benign, asymptomatic condition
characterized by excessive deposition of fat in the
mediastinum. Predisposing conditions include obesity, Cushing
disease, and corticosteroid therapy. However, this entity
is unassociated with identifi able conditions in approximately
50% of patients.
cxr and ct findings in mediastinal lipomatosis?
-the trachea remains at midline
-smooth, symmetric widening of the superior mediastinum.
-CT provides a defi nitive diagnosis by demonstrating abundant,
homogeneous, unencapsulated fat that bulges the mediastinal
contours ( Fig. 13.29 ). Displacement or compression of
mediastinal structures, particularly the trachea, is notable by
its absence. Heterogeneity within the fat suggests other primary
or superimposed conditions, such as neoplastic infi ltration,
infection, hemorrhage, or fi brosis.
most common source of air in pneumomediastinum?
Air from the lungs is the most common source of pneumomediastinum.
deep space infection along the fascial planes of the neck , extending into the mediastinum and causing chest pain
diffrential for unilateral hilar enlargement?
-small cell lung Ca
common sites of intrathoracic nodal metastasis
(renal and testicular), head and neck (skin, larynx,
and thyroid), breast, and melanoma-most common
Although 75% of patients presenting with Hodgkin lymphoma
have evidence of intrathoracic lymph node enlargement,
isolated unilateral hilar lymph node enlargement is
In distinction to unilateral nodal enlargement,
metastases are uncommon causes of bilateral hilar
nodal enlargement. The most frequent solid tumors producing
bilateral hilar disease are small cell carcinoma of the lung and
is virtually never seen without concomitant anterior
mediastinal nodal enlargement in Hodgkin disease, whereas
NHL may produce isolated hilar disease.
The pattern of lymph node involvement in sarcoidosis:
1 = right paratracheal,
2 = right hilar, and 3 = left hilar lymph node enlargement ( Fig.
In any patient in whom a
small hilum is a new radiographic fi nding, a CT scan should
be performed to assess the mediastinum for central obstructing
small hila differential?
-resection of a portion of lung
-pulmonary overinfl ation from emphysema
-diminished pulmonary blood fl ow due to congenital
pulmonary outfl ow obstruction (tetralogy of Fallot, Ebstein
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