Mediastinum And Hila Flashcards
Modality of choice for patients with probable vascular lesion, confirming cystic nature of lesions that have high attenuation due to proteinaceous contents and distinguishing thymic hyperplasia from thymic neoplasms
MRI
3 compartments of mediastinum
Anterior (prevascular), middle (visceral), posterior (paravertebral)
Most common thoracic inlet mass seen in older patients
Tortous arterial structures, in particular the confluence of the right brachiocephalic and right subclavian arteries or left subclavian artery bulging laterally into upper lobe to produce a thoracic inlet mass
Tortuous vessel is usually associated with tracheal deviation towards what side
Side of the mass
Most goiters and other inlet masses displace the trachea towards what side
Contralaterally
Uncommon vascular cause of anterior mediastinal or prevascular mass
Aneurysm arising from the right sinus of valsalva or an ascending aortic aneurysm
A prevascular mass arising from the ascending aorta as seen on lateral chest radiography that contains curvilinear calcification should suggest
Ascending aortic aneurysm or foregut cyst
Thyroid goiters, either uninodular or multinodular arise from the lower pole of the thyroid or thyroid isthmus, and can enter the superior mediastinum where
Anterior to the trachea 80%, to the right and posterolateral to the trachea 20%
Parathyroid glands can be found near the thoracic inlet at what area particularly
In or about the thymus
Most ectopic parathyroid lesions are what size?
Small adenomas (<3cm)
Uncommon masses comprised of dilated lymphatic channels
Lymphangiomas
Cystic or cavernous form of lymphangioma which is most commonly discovered in infancy and is often associated with chromosomal abnormalities, including Turner syndrome and trisomies 13,18 and 21
Cystic hygroma
Second most common primary mediastinal neoplasms in adults after lymphoma
Thymomas
Thymomas are rare in patients at what age
Under 20
Diseases associated with thymomas
Myasthenia gravis, pure red cell aplasia, hypogammaglobulinemia, grave disease and lupus
Thymomas are seen as oval, smooth or lobulated soft tissue masses arising near the
Origin of great vessels at the base of the heart
Recognized routes of spread of thymoma to the pleural space
Drop metastasis to dependent portions of pleural space
Route of spread of pleural tumor into retroperitoneum
Transdiaphragmatic spread
Rare lesions that represent remnants of the thymopharyngeal duct and contain thin or gelatinous fluid
Congenital unilocular thymic cysts
Postinflammatory in nature and have been associated with AIDS, prior radiation or surgery, and autoimmune conditions such as Sjogren syndrome, myasthenia gravis and aplastic anemia
Acquired multiloculat thymic cysts
Rare and 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
Thymolipoma
Rare and malignant neoplasms believed to arise from thymic cells of neural crest origin (amine precursor uptake and decarboxylation or kulchitsky cells)
Thymic carcinoid
Enlargement of thymus that is normal on gross and histologic examination. It occurs primarily in children as a rebound effect in response to an antecedent stress, discontinuation of chemotherapy, or treatment of hypercortisolism
Thymic hyperplasia
How many percent of patients with nodular sclerosing subtype of Hodgkin disease has the thymus involved
40-50%
Most common primary mediastinal neoplasm in adults
Hodgkin disease or NHL
Hodgkin disease involves the thorac in what percent of patients at the time of PE
85%
90% of patients with Intrathoracic involvement from hodgkin disease involves what 2 part of the thorax
Anterior mediastinal and hilar nodal groups
Most frequent site of a localized nodal mass in patients with Hodgkin disease in the mediastinum, particularly those with nodular sclerosing type
Anterior mediastinum
2 Most common types of NHL that present with mediastinal masses
Lymphoblastic lymphoma and diffuse large B-cell lymphoma
NHL most commonly involves what part of the mediastinum
Middle mediastinal and hilar lymph nodes
Uncommonly involve parts of the mediastinum in NHL, but is seen almost exclusively to it only
Juxtaphrenic and posterior mediastinal lymph node involvement
True or false: on conventional radiography, lymphoma involving the anterior mediastinum is indistinguishable from thymoma or germ cell neoplasm and presents as a lobulated mass projecting to one or both sides of the mediastinum
True
True or false: calcification in untreated lymphoma is extremely uncommon, and its presence within an anterior mediastinal mass should suggest another diagnosis
True
Parenchymal lung involvement in mediastinal lymphoma is usually the result of
Direct extranodal extension of tumor from hilar nodes along the bronchovascular lymphatics
Patient’s with succesfully treated mediastinal Hodgkin disease often have residual soft tissue density in the affected mediastinal compartments, with ______
Dystrophic calcifications commonly seen within treated nodes
Germ cell neoplasms in the anterior mediastinum are due to
Arrest of primitive germ cell migration to the gonads during embryological development
Key distinguishing factor in diagnosing primary mediastinal germ cell neoplasm versus metastasis
Presence of retroperitoneal lymph node involvement in metastatic gonadal tumor
Most common benign mediastinal germ cell neoplasm is
Teratoma
Most common type of teratoma seen in the mediastinum
Cystic or mature teratoma
Most germ cell neoplasms in the mediastinum are seen in what age group
20 to 40 y.o
Benign germ cell tumors in the mediastinum are more common in what gender; while malignant tumors are almost exclusive in
Benign- female
Malignant-males
Most common malignant germ cell tumor in the mediastinum
Seminoma
Elevated tumor markers in malignant germ cell tumors
Elevated hcg or afp
Lipomas are most commonly seen in what compartment
Anterior
Presence of soft tissue elements mixed with fat should raise possibility of what tumor
Thymolipoma or liposarcoma
Pathognomonic sign of hemangioma in chest radiographs
Recognition of phleboliths within a smooth or lobulated soft tissue mass
Hemangiomas are benign tumors composed of vascular channels and may be associated with the syndrome of hereditary hemorrhagic telangiectasia.
Most middle mediasintal lymph node masses are
Malignant, representing metastasis from lung, extrathoracic malignancy or lymphoma
5 Benign causes of middle mediastinal lymph node enlargement include
- Foregut cysts,
- vascular anomalies or aneurysms,
- sarcoidosis,
- mycobacterial and fungal infection and
- angiofollicular lymph node hyperplasia (castleman disease)
Nodular sclerosing Hodgkin disease commonly results in lymph node enlargement, predominantly within the
Anterior mediastinum and thymus
What type of leukemia can cause intrathoracic lymph node enlargement
T-lymphocytic varieties
The lymph node enlargement is usually confined to the middle mediastinal and hilar nodes
Most common source of metastases to middle mediastinal nodes is
Lung cancer
Paratracheal and aorticopulmonary nodes are most commonly involved
A lymphoproliferative disorder characterized by enlargement of hilar and mediastinal lymph nodes, predominantly in the middle and posterior mediastinal compartments
In the more common hyaline vascular type, the disease is localized to one lymph node region and presents as an asymptomatic mediastinal soft tissue mass.
Angiofollicular or giant lymph node hyperplasia, aka Castleman disease
Histologically, there is the 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.
Multicentric form of castleman disease is most often associated with
HIV and human herpes virus 8 infection
Unicentric lesions in castleman disease is treated by
resection
multicentric castleman disease with HHV-8 infection is treated by
rituximab
multicentric castleman disease with HHV-8 negative disease is treated by
siltuximab
common mediastinal lesions that typically present as asymtomatic masses on routine chest radiographs in young adults. CT and MR show findings characteristic of the cystic nature of these lesions
Foregut and mesothelial cysts
results from anomalous budding of the tracheonbronchial tree during embryologic development
Bronchogenic cysts
Majority of bronchogenic cysts (80-90%) arise within the mediastinum in the vicinity of
tracheal carina
• Bronchogenic cysts are seen as soft tissue masses
in the subcarinal or right paratracheal space on frontal chest radiographs
Method of choice for diagnosis of mediastinal cysts
MDCT
Arise form the parietal pericardium and contain clear serous fluid surrounded by a layer of mesothelial cells.
Pericardial cysts
Most often, pericardial cysts arise in the
anterior cardiophrenic angle, with right-sided lesions being twice as common
Approximately 20% of pericardial cysts arise where
more superiorly within the mediastinum
3 Differential diagnosis for cardiophrenic angle masses
pericardial cyst,
enlarged epipericardial fat pad,
enlarged juxtaphrenic lymph nodes
majority of esophageal neoplasms, excluding lesions that arise at the esophagogastric junction are
squamous cell carcinomas
distal esophageal tumors present in the imaging as
distal esophageal dilatation
proximal esophageal tumors present in imaging as
thickening of the tracheoesophageal stripe
imaging diagnosis of esophageal tumors is usually made by
barium esophagram and confirmed by endoscopic biopsy
benign esophageal lesions that present as smooth, solitary, mediastinal masses, projecting laterally from the posterior mediastinum on frontal chest radiographs
leiomyoma and GIST
Several benign esophageal neoplasms, including:
•leiomyoma,
•fibroma, and
•lipoma,
•The absence of esophageal dilatation above the mass helps distinguish benign tumors from carcinoma.
leiomyoma and GISTs in the esophagus generally involves what part of the esophagus
lower third; from the level of subcarinal space to esophageal hiatus
False diverticula representing mucosal outpouchings through defects in the muscular layer of esophagus
pulsion diverticula
pulsion diverticula arises where
cervicothoracic esophageal junction or distal esophagus
large proximal pulsion diverticula
zenker
pulsion diverticular that appear as a retroesophageal superior mediastinal mas containing air-fluid level on upright chest radiographs
zenker
distal pulsion diverticular presents as
juxtadiaphragmatic mass with an air-fluid level projection right of midline
esophageal lesion that may produce a mass that courses vertically over the length of the mediastinum, projecting toward the right side on frontal chest radiographs
dilated esophagus from functional (achalasia, scleroderma) or anatomic obstruction (stricture, carcinoma)
may produce a round or lobulated retrocardiac mass in patients with portal hypertension
esophageal varices
common cause of mass in the inferior visceral mediastinum
hiatal hernia
results from separation of the superior margins of diaphragmatic crura and stretching of phrenoesophageal ligament
hiatal hernia
gastric hernia
sliding hernia
fundal hernia
paraesophageal hernia
fluid-filled masses lined by enteric epithelium
enteric cysts
esophageal cysts usually arise
intramurally or immediately adjacent to the esophagus
when enteric cyst has a persistent communication with the spinal canal (canal of Kovalevsky) and is associated with congenital defects of thoracic spine (anterior spina bifida, hemivertebrae or butterfly vertebrae, it is termed
neuroenteric cyst
tumors arising from intercostal nerves
schwannoma, neurofibroma
tumors arising from sympathetic ganglia
ganglioneuroma, ganglioneuroblastoma, neuroblastoma
tumors arising from paraganglionic cells
Paragangliomas
chemodectomas
pheochromocytomas
most common neurogenic tumors in children
neuroblastoma and ganglioneuroma
neurogenic tumors in adults
schwannoma and neurofibroma
neurogenic tumor comprised of spindle cells that arise from schwann cells which appears encapsulated and contains interspersed neurons
neurofibroma
neurogenic tumor comprised of spindle cells that arise from schwann cells that is not encapsulated and contains no neuronal elements
schwannoma
multiple lesions in the mediastinum, particularly bilateral apicoposterior masses, are virtually diagnostic of
neurofibromatosis
CT demonstration of a tumor extension from the paravertebral space into the spinal canal via an enlarged intervertebral foramen is characteristic of a
“dumbbell” neurofibroma
modality of choice for imaging suspected neurofibroma
MRI
malignant neuroblastoma are seen almost exclusively in
children under the age of 5
these tumors generally present as elongated, vertically oriented paravertebral soft tissue masses with a broad area of contact with the posterior mediastinum
ganglioneuroma and neuroblastoma
tumors that arise from neural crest or chromaffin cells that lie in proximity to the thoracolumbar sympathetic ganglia of autonomic nervous system
mediastinal paragangliomas
majority of mediastinal paragangliomas arises in
anterior or middle mediastinum
Most common primary sites of thoracic spinal metastases
bronchogenic, breast or renal cell carcinoma
•Neoplastic processes are usually easily identified by expansion and destruction of vertebral bodies, with sparing of intervertebral disks.
important clues to the diagnosis of paravertebral abscess secondary to tuberculosis or bacterial infection
narrowing of adjacent disk space and destruction of vertebral endplates
Infectious spondylitis is distinguished from neoplastic processes by the presence of a paravertebral mass centered at the point of maximal bone destruction.
extramedullary hematopoiesis in the spine is seen commonly where
lower thoracic and upper lumbar
- Extramedullary hematopoiesis is seen almost exclusively in conditions associated with ineffective production or excessive destruction of erythrocytes, such as:
- thalassemia major,
- congenital spherocytosis, and
- sickle cell anemia.
Anomalous herniation of spinal meninges through an intervertebral foramen, resulting in a paravertebral soft tissue mass
Lateral thoracic meningoceles
Lateral thoracic meningoceles are usually discovered at what age and are more common on what side
Middle-aged patients and more common in the right
There is high association between lateral meningoceles and
Neurofibromatosis
Additional clues to the diagnosis of lateral thoracic meningoceles, aside from a round, well-defined paraspinal mass that is indistinguishable from neurofibroma include
Rib erosion, enlargement of adjacent neural foramen, vertebral anomalies or kyphoscoliosis
When a lateral meningocele is associated with kyphoscoliosis, it is usually found where
Apex of the scoliotic curve, on the convex side
Diagnostic imaging of choice for lateral thoracic meningocele
MRI
In mri, lateral thoracic meningocele demonstrate
Herniated subarachnoid space
Caused by a bacterial infection that most often develops following esophageal perforation or is a complication of cardiothoracic or esophageal surgery
Acute mediastinitis
Spontaneous esophageal perforation following prolonged vomiting is termed
Boerhaave syndrome
In this condition, a vertical tear occurs along the left posterolateral wall of the distal esophagus, just above the esophagogastric junction, leading to signs and symptoms of acute mediastinitis
boerhaave syndrome
Most common chest radiograph findings in acute mediastinitis
Widening of superior mediastinum in 65% of patients and pleural effusion in 50%
Sensitivity of esophagogram from detecting contrast leakage is highest when the study is obtained within
24 hours of perforation
Radiologic study of choice for diagnosis of acute mediastinits
MDCT
Associated with poorest outcome in acute mediastinitis
Esophageal perforation
hallmarks of chronic fibrosing (sclerosing) mediastinitis are
chronic inflammatory changes and mediastinal fibrosis
most common cause of chronic fibrosing mediastinitis
granulomatous infection, usually secondary to histoplasma capsulatum
- Idiopathic mediastinal fibrosis,
- which is probably an autoimmune process, is related to fibrosis in other regions, including the:
- retroperitoneum,
- intraorbital fat, and
- thyroid gland.
most commonly affected structure in chronic fibrosing mediastinitis
SVC
manifests as headache, epistaxis, cyanosis, jugular venous distention, edema of the face, neck and upper extremities
SVC syndrome
most serious and potentially fatal manifestation of fibrosing mediastinitis
obstruction of central pulmonary veins, which produces pulmonary edema that may mimic severe mitral stenosis
chronic fibrosing mediastinitis present as ____ in chest radiographs
asymmetric lobulated widening of the upper mediastinum, most often in the right
most common finding in chronic fibrosing mediastinitis
enlarged lymph nodes with calcifications
In this condition, the mediastinum develops a flat or slightly convex outward contour, unlike the round, lobulated or irregular contour seen with enlarged lymph nodes or localized mediastinal mass
mediastinal hemorrhage
benign, asymptomatic condition characterized by excessive deposition of fat in the mediastinum
mediastinal lipomatosis
• In multiple symmetric lipomatosis, the cardiophrenic angles, paraspinal areas, and the anterior mediastinum are spared.
Periscapular lipomas may also be seen. The trachea is often compressed or displaced by fat in patients with this condition, whereas this is not seen in simple lipomatosis.
mechanism of pneumomediastinum formation
involves sudden rise in intrathoracic and intra-alveolar pressure that leads to alveolar rupture
AKA Macklin effect in pneumomediastinum
extra-alveolar air first collects within the bronchovascular interstitium and then dissects centrally to the hilum and mediastinum
in boerhaave syndrome, in addition to pneumomediastinum, hydropneumothorax and pneumoperitoneum are mostly seen on what side
left
describeds the substernal chest pain caused by the intramediastinal extension of neck or laryngeal infections
ludwig angina
True or false: mediastinal air without infection is generally asymptomatic and does not require treatment
true
unilateral hilar enlargement resulting from metastatic lymph node involvement is often seen in
small cell carcinoma
malignancies most often associated with intrathoracic nodal metastases are
genitourinary (renal and testicular); head and neck (skin, larynx, thyroid); breast and melanoma
lymphatic spread of tumor to retroperitoneal nodes and up the thoracic duct to posterior mediastinum is the mode of spread in
renal cell carcinoma and seminoma
reflux of tumor emboli in thoracic duct and anterior mediastinal lymph nodes to hilar, paratracheal and intraparenchymal lymphatics are due to
incompetent valves
extrathoracic neoplasm with highest incidence of intrathoracic nodal metastasis
melanoma
unilateral hilar or mediastinal lymph node enlargement is a characteristic feature in
primary pulmonary tuberculosis
other bacterial infections that have been associated with unilateral hilar lymph node enlargement include
plaque, tularemia and anaerobic lung abscess
viral infections most commonly associated with hilar lymph node enlargement are
infectious mononucleosis and measles pneumonia
characteristic finding in patients with pneumonic plague
detection on unenhanced CT of increased attenuation within hilar and mediastinal nodes that drain regions of parenchymal involvement owing to intranodal hemorrhage
most common intrathoracic manifestation of mononucleosis
hilar lymph node enlargement
vascular disorders that produce unilateral pulmonary artery enlargement include
- postenotic dilatation of left pulmonary artery from valvular or postvalvular pulmonic stenosis,
- pulmonary artery aneurysms and
- distention of PA by bland or tumor thrombosis
most frequent solid tumors producing bilateral hilar disease are
small cell carcinoma of the lung, lymphoma, malignant melanoma
Bilateral hilar lymph node involvement by lymphoma is more common in hodgkin or non-hodgkin
hodgkin disease
severe pulmonary overinflation from emphysema or in those with diminished pulmonary blood flow due to congenital pulmonary outflow obstruction (TOF, ebstein anomaly) or rarely fibrosing mediastinitis may cause what change in the hilum
Bilaterally small hila
most common causes of small hilum are
atelectasis and resection of a portion of lung, hypoplasia of PA often with associated abnormalities of ipsilateral lung (hypogenetic lung syndrome, Swyer-James syndrome)
