Mediastinum

Question 1

mediastinal compartments

Answer 1

anterior: prevascular and precardiac anterior mediastinum (sternum/pericardium, ascending aorta)
middle: (heart and posterior tracheal wall)
posterior: (posterior trachea and posterior pericardium)

Question 2

contents of anterior mediastinum

Answer 2

thymus, lymph nodes, thyroid gland if it extends inferiorly

Question 3

middle mediastinum contents

Answer 3

heart, ascending aorta/arch, great vessels, trachea/bronchi, LN, phrenic/vagus/recurrent laryngeal nerves (pass through AP window)

Question 4

posterior mediastinum

Answer 4

esophagus, descending thoracic aorta, azygos/hemiazygos, thoracic duct, vagus nerve, LN

Question 5

define: line, stripe, interface on CXR

Answer 5

line: interface of tissue with air on both sides
stripe: air and adjacent soft tissues
interface: contact of two soft tissue structures of different densities

Question 6

anterior junction line

Answer 6

4 layers of pleura between R/L lung, anterior junction

projects over superior 2/3 of sternum

abnormality suggests anterior mediastinal mas

Question 7

posterior junction line

Answer 7

4 layers of pleura between R/L lung, anterior junction

projects through trachea; above clavicles

abnormality: posterior mediastinal mass/aortic aneurysm

Question 8

paratracheal stripes

Answer 8

pleura where medial aspect of lung abuts trachea

abnormal R paratracheal stripe: pleural thickening, or paratracheal mass/thyroid

abnormal L paratracheal stripe: as above + mediastinal hematoma

Question 9

posterior tracheal stripe

Answer 9

posterior wall of trachea and pleura of medial R lung

seen only on lateral radiograph

Question 10

paraspinal lines

Answer 10

interfaces that appear as lines abutting posterior mediastinum

abnormal: posterior mediastinal mass–hematoma, neurogenic tumor, aortic aneurysm, extramedullary hematopoiesis, esophageal mass, osteophyte

Question 11

azygoesophageal recess

Answer 11

posteromedial RLL and retrocardiac mediastinum

abnormal: esophageal mass, hiatal hernia, left atrial enlargement, LN

Question 12

AP window

Answer 12

bound by aortic arch and top of pulmonary artery as well as esophagus/trachea/left mainstem bronchus

Question 13

abnormal bulging of AP window ddx

Answer 13

LN, left phrenic nerve, recurrent laryngeal nerve, left vagus nerve, ligamentum arteriosum, left bronchial arteriosum, thoracic aortic aneurysm

Question 14

retrosternal space

Answer 14

lateral radiograph, anterior mediastinum

obliteration: mass, RV dilation, pulmonary artery enlargement
increased: emphysema

Question 15

aortic nipple

Answer 15

left superior intercostal vein

small round shadow to the left of the aortic knob on AP

may dilate in SVC obstruction

Question 16

hilum overlay sign

Answer 16

hilar vessels visualized through mass

mass must be in anterior/posterior mediastinum, NOT middle

Question 17

localizing mass to anterior mediastinum on XR

Answer 17

hilum overlay sign

obliteration of retrosternal clear space

Question 18

localizing middle mediastinal mass

Answer 18

distortion of paratracheal stripes

convexity of AP window

Question 19

localizing posterior mediastinal mass on XR

Answer 19

distortion of azygoesophageal recess, posterior junction line, displacement of paraspinal lines

Question 20

anterior mediastinal mass

Answer 20

thymoma/thymic epithelial neoplasm, teratoma/germ cell tumor, thyroid, terrible lymphoma

Question 21

thymoma

Answer 21

45-60yo, associated with myasthenia gravis

also associated with red cell aplasia, hypogammaglobulinemia, paraneoplastic syndrome, malignancy

Question 22

considerations for thymoma

Answer 22

intact capsule, invasion

invasion into airways, chest wall, great vessels, phrenic nerve

check for elevation of hemidiaphragm

drop mets to pleural/pericardial surfaces

Question 23

thymic carcinoma

Answer 23

poor prognosis, aggressive and mets to lungs, liver, brain, bone

Question 24

thymic carcinoid

Answer 24

neural crest origin; hormonally active and can secrete ACTH (cushings)

associated with MEN I/II

scan with In-111 octreotide

Question 25

thymic cyst

Answer 25

secondary to radiation therapy (Hodgkin), AIDS (multilocular), or congenital (thymopharyngeal duct)

Question 26

thymolipoma

Answer 26

fat lesion interspersed with soft tissue

Question 27

germ cell tumor (anterior mediastinum)

Answer 27

teratoma and seminoma most are benign although malignant GCT usually in males

Question 28

most common anterior mediastinal germ cell tumor

Answer 28

teratoma

Question 29

teratoma imaging features (anterior mediastinum)

Answer 29

encapsulated, cystic with fat/calcifications; may be malignant if large and irregularly shaped

Question 30

seminoma

Answer 30

most common malignant mediastinal germ cell tumor exclusively in men

Question 31

thyroid lesions

Answer 31

goiter, thyroid neoplasm, thyroiditis

Question 32

mediastinal mass: lymphoma

Answer 32

HL and NHL superior mediastinal nodes involved: prevascular, AP, paratracheal

Question 33

non-lymphomatous adenopathy

Answer 33

silicosis, coal workers pneumoconiosis, sarcoidosis, active TB, fungal infection, Castleman disease, vascular mets (RCC, thyroid, lung sarcoma, melanoma)

Question 34

Castleman disease

Answer 34

angiofollicular lymph node hyperplasia; vascular thoracic lymph node enlargement children/young adults OR older patients/AIDS systemic disease: fevers/anemia/lymphoma treat: surgical resection and chemotherapy for systemic dx

Question 35

epicardial fat pad

Answer 35

silhouettes cardiac border on frontal radiograph; may look like cardiomegaly

Question 36

pericardial cyst

Answer 36

benign cystic lesion at right CP angle

Question 37

morgagni hernia

Answer 37

diaphragmatic hernia through foramen of Morgagni containing omental fat/bowel; right side

Question 38

middle mediastinal masses

Answer 38

lymphadenopathy, ascending aortic arch/aneurysm, enlarged PA, foregut duplication cyst

Question 39

hilum convergence sign

Answer 39

peripheral pulmonary arteries converge into a "mass"

Question 40

foregut duplication cysts

Answer 40

bronchogenic cysts, esophageal duplication cyst, neurenteric cyst

Question 41

posterior mediastinal mass

Answer 41

neurogenic tumor, hiatal hernia, descending TAA, extramedullary hematopoiesis, lateral meningocele , esophageal neoplasm, foregut duplication cyst, paraspinal abscess

Question 42

neurogenic tumors: PNS and SNS

Answer 42

peripheral nerve tumors (adults): schwannoma, neurofibroma, malignant peripheral nerve sheath tumor sympathetic ganglion tumor (peds): ganglioneuroma, neuroblastoma, ganglioblastoma

Question 43

posterior mediastinal mass: hiatal hernia XR

Answer 43

air fluid level above diaphragm

Question 44

posterior mediastinal mass: extramedullary hematopoeisis

Answer 44

soft tissue paravertebral mass in pts with severe hereditary anemia or thalassemia/sickle cell may represent herniation of vertebral marrow or elements of reticuloendothelial system bilateral and inferior to T6

Question 45

posterior mediastinal mass: lateral meningocele

Answer 45

herniation of spinal meninges through intervertebral foramen or vertebral body defect; associated with NF