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62 terms

Mediastinum

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Normal Thymus
Lt is larger; max at puberty (50g)involutes after puberty; "thymic sail" sign rt lobe; "wave" sign lt lobe from scalloping by ant ribs; infants CT HU~ muscle 26 HU av + 20-30 post CM; >25y fatty
Pericardial recesses
superior, pulmonic, retroaortic, preaortic
Trachea
oval AP>trans at thoracic inlet; at the manubrium rounded just above the carina shows a horizontal oval ;horseshoe-shaped;
Tracheal Bronchus
only right is known; Displaced (usually apical segm) or supernumarary ( tracheal lobe)
Accessory cardiac bronchus.
from the medial wall of the RBI just below the takeoff of the RULB
DD of mediastinal mass based on
location ( ant/mid/post); nature ( solitary/multifocal/diffuse); Attenuation ( fat/fluid/soft tissue/ca++/post CM)
Anterior M anatomic
sternum-pericardium; fat, ly,
Middle M anatomic
between ant and post mediastinum
Posterior M anatomic
heart-spine; DA; Az; Sup intercostal vein; Thoracic D; Esoph; Vagus
Superior M anatomic
above pericardium, below root of neck; trachea; esoph; thymus; gr vessels
Anterior M Xray
sternum-ant tracheal wall/post border of the heart; thymus/heart/asc aorta/ant portion MPA/pericardium/fat/lymph; ant junction line/cardiophrenic angles/retrosternal stripe/retrosternal space
Middle M Xray
between Ant and Post; trachea/bronchi/SVC/ mid AArch/Azygous/ lymph/Esophagus/Desc Aorta/; Rt and Lt paratracheal stripes/ SVC interface/AP window/Lt subclavian art interface/Azygoesophageal recess/preaortic interface
Posterior M Xray
post to line 1 cm behind the ant margin of the vertebral coumn-chest wall; vertebral bodies/paravertebral tissues/desc aorta/ post azygous vein, hemiazygous vein/ lymph nodes/ paravertebral stripes
Anterior M CT prevascular space
Thymic - hyperplasia/thymoma/thymic CA/ thymic carcinoid/ thymic cyst/thymolipoma/thymic lymphoma and metast
Germ cell tu - teratoma/ seminoma/ Non-seminomatous germ cell tu
Thyroid - goiter, neoplasm
Parathyroid tu or hyperplasia
Lymph nodes - Hodgkins Ly
Vascular malformations
Mesenchymal - lipoma, lipomatosis
Foregut cyst
hemangioma, lymphangioma
Anterior M CT cardiophrenic angle
Lymph nodes - Ly, mets
Pericardial cyst
Morgagni Hernia
Thymic masses
Germ cell tu
Middle M CT pretracheal space
Lymph nodes - Lung ca, sarcoidosis, Ly, Mets, Inf ( tb)
Foregut cyst
Tracheal Tu
Mesenchymal - lipoma, lipomatosis
Thyroid abnorm
Vascular malformations
hemangioma, lymphangioma
Middle M CT AP Window
Lymph nodes - Lung ca, sarcoidosis, Ly, Mets, Inf ( tb)
Mesenchymal - lipoma, lipomatosis
Vascular malformations
Chemodectoma
Foregut cyst
Middle M CT subcarinal and asygoesophageal recess
Lymph nodes - Lung ca, sarcoidosis, Ly, Mets, Inf ( tb)
Foregut cyst
Dilated Azygous Vein
Esophageal Masses
Varices,
Hernia
Posterior M CT (paravertebral region)
Neurogenic Tu - nerve sheath/ sympathetic ganglia/paraganglioma
Foregut cyst
Meningocele
EMH
Pseudocyst
Thoracic spine abn
Hernia
Esoph masses, varices
Mesenchymal - lipoma, lipomatosis
Lymph nodes - Hodgkins Ly, mets
Azygous, hemiazygous dilated
hemangioma, lymphangioma
thymic or germ cell
Thymic hyperplasia
Incr in size, normal appearance; assoc w AI diseases ( grave's) red blood cell aplasia, sarcoidosis
Thymic Rebound
stress thymus decreses(-40%), then increases(150%); 1-9 mo after; ; assoc w recovery from chemo/stress/burns/; lymphoma - DD rebound vs recurrent tu
Thymoma
thymic epithelium; most common thymic; 50-60yo;Myastenia gravis in 30-40%(10-30% MG have thymoma) Invasive in 30% non invasive 70%, not B or M. Mets out of thorax 3-5%; RF: Sharp margin smooth or lobulated; usually projects to one side of M; Retrosternal clear space or CPAs; CTF: Focal or lobulated mass; homogeneous or cystic; may Ca++; difficult to Dx invasion with certainity surgical staging; MR is limited; Tx Resection +Rad or chemo for invasive beyond capsule; 5ys 75-90% non invasive; 50-60% invasive
Thymic ca
thymic epithelium; 50yo; M on histology; common invasion ,dist M 50-60%; MG rare; appearance indistinguishable from thymoma unless mets visible
Thymic Carcinoid
from neural crest (APUD) cells; usually M; mets maybe; 45yo; Cushing 25-40%; MEN I or II in 20%; appearance like thymoma; more aggressive; dense CMEnhancement; 5ys 65%
Thymolipoma
fat and thymic tissue; rare; B; young; asymptomatic; large droopy mediastinal mass w fat and strands of tissue; no invasion or recurrence
Thymic Cyst
uncommon; congenital(rare) or acquired(Rad Tx, thoracotomy); Water HU +- hemorrhage and fat; DD cystic lesions w thymoma and lymphoma: thin wall, no mass lesion; water density; no enhancement; can be Ca++ wall
Thymic Ly and Mets
Hodgkin: non specific; + ly nodes; Mets: from lungs and breast; non specific; + ly nodes;
Germ cell : Teratoma
all three germinal layers; 95% ant M 5% Post M; (1)mature - well-diff tissues hair skin, cartillage; B; mc germ cell tu; young; asymptomatic unless large (2) cystic (dermoid cyst) only ectoderm layer skin; B (3) immature - fetal tissues; B for children M agressive for adults(4) malignant - poor prognosis; men RF: smooth round or lobulated; one side of M; Retrosternal clear space or CPAs; Ca 20%; mature big CTF: prevascular space 95% post M 5%; combination of fluid(varyable HU) filled cysts(90%); fat(75%); soft and Ca++ (50%); M compresses and enhances in thick capsule
Germ cell : Seminoma
Men, 29yo; 30% germ cell; large lobulated ant M mass; homogeneous; 5ys 50-75%; radiosensitive
Germ cell : NonSeminoumatous
Cell types: Embryonal CA; Endodermal sinus (yolk sac) tu; ChorioCA; mixed types; large lobulated ant M mass; inhomogeneous infiltrative, ; poor prognosis
Thyroid
almost always connected to cervical thyroid; anterior M 75-90%; posterior M in 10-25%; mulitinodular goiter mc, ca, thyroiditis; RF:sup M mass w trachea narrowing and displacement; CTF high HU mass w marked and prolonged enhancement; inhomogeneous and cystic punctate Ca++; difficult to diff goiter from Ca
Parathyroid
mc parath adenoma ( in lower glands)
Lymphoma HD
30% from LY; 85% thoracic involvement; variable appearance
Lymphoma NHL
40% thoracic involvement; common in one! node group
Ly: Castleman Ds
Angiofollicular ly node hyperplasia; unknowm etiology; localized or multicentric; dense enhancement of ly nodes on CT!; 90% hyaline vascular type ( children or young/asymptomatic/localized/B) plasma cell type ( 40-50yo/multicentric/ progressive/ systemic illness) steroids, chemo, resection is tried; axillary, abdominal, other maybe involved
Ly: Sarcoidosis
mediastinal ( mc rt paratracheal) and hilar bilateral(95%) symmetrical 1-2-3 pattern typical +- APW; Ca++ can be present on CXR ( ense, stippled, eggshell) om CT 25-50%; rarely necrotic or enhancing maybe; not as large as Ly
Ly: Inf: TB
active; more often in children; hilar and mediastinal; side of disease; rt side predominates; rt paratracheal is most common; if >2cm necrotic center ( 40-60 HU) often in AIDS+Tb; can obliterate M fat with necrotic area - >abscess ( cold abscess)
Ly: Inf: Histoplasmosis
hilar and mediastinal; acute or subacute; paratracheal, subcarinal, hilar; irreg enhancement, rim enh or necrosis mb
Fibrosing Mediastinitis
TB/Histo/Sarcoidosis/AID/Drugs/Retroperitoenal Fibrosis/Idiopathic; Ca++common; Narrows SVC, trachea, LMB, RPA
Lipomatosis
FAT =-40 - -130 HU; assoc w Cushing, steroid, obesity, idiopathic 50%; RF: symmetrical upper M; smooth homogeneous, low HU; no compression or displacement; sometimes in CPA and paraspinal. DD mediastinitis, hemorhage, tu infiltration, fibrosis
Lipoma LipoSarcoma
mc prevascular space
Hernias with Fat
Morgagni rt CPA; Bochdalek lt post lat
Foregut Duplication Cyst: Bronchogenic Cyst
60% of FDC; wall contains resp epithelium, smooth muscle, mucous gland or cartilage; 50% subcarinal; 20% paratracheal; 10% retrocardiac; round oval smooth margins; wall thin or invisible on CT, may calcify; fluid 0-40 HU;Up to 50% may be soft tissue attenuation on CT! high signal T1MR Compl inf or hemorhage; Tx resection
Foregut Duplication Cyst: Esophageal Duplication Cyst
GIT mucosa lining, connected to E, no cartilage. 60% in lower post M dysphagia /chest pain /asymptomatic.
Foregut Duplication Cyst:Neurenteric cyst
+vertebral abnormality in 50% cases; MR fo rintraspinal involvement
Pericardial cyst
65% Rt CPA 25% Lt CPA; sharp margin, smooth, low HU
Mediastinal pseudocyst
Pancreatic pseudocyst; symptoms
Lymphangioma, cystic Hygroma
rare, present in childhood; neck 75%, axila 20%; capillary, cavernous or cystic ( hygroma)unilocular or multilocular
Hemangioma
ant or post M; vascular, B cavernous 75%( capillary, venous); young
Esophageal Ca
CT: thickening wall; narrowing of lumen; loss of periesophageal fat planes; adenopathy
Esophageal Dilatation
tu; stricture ; achalasia
Esophageal Varices
portal pressure up; CT serpingious soft-tissue opacities identing E wall; enhancing post CM
Hiatal Hernia
...
Mediastinal abscess
...
Neurogenic Tu: Peripheral nerve sheath
Shwannoma (neurilemmoma), neurofibroma, neurogenic sarcoma; adults; round, elliptical or lobulated paravertebral mass; 1-2 interspaces length; rib or vertebral abnormalities in 50%; lower HU than muscle in 70%; 1/3 with NF has NFtosis
asymptomatic /compression. MR is very useful in the exclusion of intraspinal tumor extension, a critical assessment prior to surgical excision. Schwannomas are benign neoplasms, and while malignant degeneration is reported, it is very rare. Affected patients are typically cured after complete surgical excision.
Neurogenic Tu: Symp Ganglia
Gneuroma; GNBlastoma; NBlastoma; oblong paravertebral mass; Ca++ 20%; children 20% of post mass
Neurogenic Tu: Paraganglioma(chemodectoma)
mc APW maybe in post M or atria, from autonomous ganglia; on CT dense enhancement!; compression of M structures -> symptoms; 131-I-MIBG fo rcatecholamine producing tu; octreotide scintigraphy; 10% M and invasive ;resection; local recurrence is common in APW.
Meningocele
ant or lat; assoc w NFsis; herniation of spinal meninges through intervertebral foramen
EMH
paravertebral mass in patients with severe anemia ( thalassemia, SCA). Lobulated paravertebral masses, multiple and bilateral, well marginated soft tissue HU ( 30-65)
Thoracic Spine abnormalities
tu, spondilitis; # w hemorhage; bilateral, fusiform.
Enhancing M mass
ly nodes/ Thyroid Parathyroid lesion/carcinoid/lynphangioma/hemangioma/paraganglioma. Diff to diff M mass from ly nodes
Mets
extrathoracic uncommon 3% ( head neck/breast/GI/breast/melanoma)