1) Mediastinal masses can occur in the three compartments of the mediastinum and are diverse in pathology. 2) CT is usually the initial imaging modality of choice to determine the location and characteristics of the mass. 3) Tissue biopsy is often required before treatment planning to determine the specific diagnosis, as the approach depends on factors such as location, imaging features, and patient age.

1. Mediastinal Masses
Dr. Dharma Ram Poonia,
Assistant Professor, Surgical Oncology,
All India Institute of Medical Sciences, Rishikesh
15.01.2020

2. • Anatomy, Division
• Pathology
• Workup
• Treatment

3. Mediastinum
• Anatomic space in the thoracic cavity bounded by the
• Pleural cavities laterally
• Thoracic inlet superiorly
• Diaphragm inferiorly
• Sternum anteriorly
• Chest wall posteriorly
• Subdivision (Fraser’s scheme) that subdivides into
• anterior, middle, and posterior compartments

4. Great vessels
LNs
Trachea
Esohphagus
Thymus
Fat
Heart with pericardium
Great vessels
Trachea
Nerve
LNs
Esophaus
DT aorta
Nerves
LNs
Classification
Location:
Content/origin:
FAT/CYST/SOLID

6. Incidence
• 3% of all lesions of Chest.
Adults
• Thymomas and thymic cysts (26.5%),
• Neurogenic tumors (20.0%),
• Cysts (16.1%),
• Germ cell tumors (13.8%)
• Lymphomas (12.7%)
Children
• Neurogenic tumors (41.6%),
• Germ cell tumors (13.5%),
• Primary cysts (13.4%) & lymphomas (13.4%)

7. Clinical Presentation
• Incidental in > 50 % of the cases
1. Compression/ Infiltration  S/S
Trachea
Oesophagus
Great Vessels
Lung
2. Non Specific like Fatigue/ Weight Loss
3. Paraneoplastic Syndrome: PRCA, Hypogamaglobulimia,
Smooth Muscle degenration
4. Myasthenia Gravis.
5. Pel Ebstein Fever

8. Work up
• CXR usually first imaging
• Location and content of tumor is of the most
important factor to reach diagnosis, apart from
clinical Exam & age.
Imaging
Tissue Diagnosis

9. Investigations
• Sniff Test (Daignostic Fluroscopy) - Sos
• CT Thorax/ MRI Thorax
• Extent & Resectabilty.
• Content
• Enhancement pattern
• PET CT (FDG)
• Thymic carcinoma
• Invasive Thymomas
• Problem solving

10. Other, based on clinical suspicion
• Parathyroid adenomas or functioning parathyroid carcinomas
may secrete parathormone.
• Pheochromocytomas may secrete various catecholamines (in
serum and urine), which may cause hypertension.
• Carcinomas may secrete carcinoembryonic antigen.
• Nonseminomatous germ cell neoplasms may secrete AFP or β-
human chorionic gonadotropin (β-HCG).
• Skin tests for tuberculosis, histoplasmosis, and
coccidioidomycosis may also yield positive results.
• Other diagnostic tests for mediastinal tuberculosis include
sputum cytology, CXR, and urine cytology

11. Direct Sx, without Biopsy
• Limited indication
• Threshold for Direct Sx reduced with emergence
of VATS.
• Cystic lesion
• Benign appearing solid tumors (neurogenic
tumors)
• mature teratomas
• Early stage thymomas.

12. Always needs Biopsy
• Poorly demarcated lesion of anterior and middle Ms.
• Eg. Thymomas, thymic carcinomas, seminomas,
nonseminomatous, germ cell tumors, and
lymphomas are quite similar in radiographic
appearance but are quite different in treatment
strategy.
• Neither guidelines nor standard of care approach
exist regarding Bx methods.
• Technique of Bx, depends on
• Location of tumor, Age and institutional expertise.

13. • Many methods are there.
• Avoid trans pleural Bx.
• Trucut preferred over FNAC
• Minimally invasive preferred over Invasive Approaches
• Limited indication when Surgical resection directly
indicated, without Bx.

14. • Ultrasound (US)-
guided
endoscopic biopsy
• EBUS TBNA middle
ms, but small tissue
sample and time
consuming/ technical
expertise.
• EUS FNA  Posterior
Ms, may be useful
sometimes.
• Percutaneous
image-guided
needle biopsy
• US guided  may be
used for ant ms mass,
through SC fossa
• CT guided more often
used, and can Bx
almost all lesion.
• Pneumothorax (8-
61%)
• Hemoptysis (1-6-3%)

15. • Parasternal anterior
mediastinotomy
• (Chamberlain’s approach )
• May be used, When Needle
Bx failed or not feasible, but
with advent of VATS, its
indication fallen significantly.
• 3-4 cm parasternal
Transverse incision.
• Risk of Injury to IMA.
• Useful for AP window and
para aortic masses.
• May be done, under LA.
• Cervical
mediastinoscopy and
videomediastinoscopy,
and extended CME.
• Under GA
• 2 cm incision @ 2cm
above, sternal notch.
• Pretracheal, paratracheal
and subcarinal lesion.
• Injur to lt RLN & great
vessels.
• VATS
• Can Bx almost all lesion with
examination of pleural
cavity.
• Under GA and DLT.
• Transpeural, so theoretical
risk of tumor seedling.
• Open surgical
procedures.

16. Approach
1. Is the mass actually in the
mediastinum or is it in Lung
2. Determine which compartment.
3. Radiological character, including
contents
4. Than Tissue Diagnosis as clinically
indicated.
That will narrow down DD and guide for Further Management

17. 1st Question
Mediastinal
• As these are lined by
mediastinal pleura they
often have
• smooth contour
• Tapered borders.
• Cross midlines.
Lung
• They are parechymal
• Surrounded by air
• May contain air
brochogram
• Will be on one side.

18. • Anterior MS 60% malignant
• Middle 30% malignant
• Post 15% malignant
Adults 50% malignant
Child 25% malignant

19. Antero superior
Ms 60%
MC  thymoma
Middle Ms
20%
• MC mass 
Cysts (20% of all
Ms Masses)
• Most common
tumor
Lymphoma
Posterior Ms
20%
Mainly
neurogenic
tumours
(Over all most
common 20%)
4”A”
1. Adenopathy
2. Awful primary
3. Aneurysm
4. Abnormal
developmental
4“Ts”:
1. Thymoma (MC 50
%) > 40yr
2. Teratoma
(GCT) 20% < 40 yr
3. Thyroid goiter
4. “Terrible”
lymphoma
1. Nerve sheath tumors
Sch/NF
2. Paraganglionic tumors
3. Meningoceles
4. Mesenchymal tumors
5. Lymphoma
6. Pheochromocytoma
7. Duplication cysts.

20. Fatty
masses
• Lipomas –
• 1.5-3% of all primary med masses.
• anterior mediastinum
• Homogenous, fat attenuation ( -100 HU)
• Liposarcoma
• Posterior mediastinum,
• Mostly symptomatic at present..
• CT  Heterogeneus lesion with fat density areas.
• Thymolipoma
• Rare, 5% of thymic masses
• Asymptomatic
• CT  large and well encapsulated mass with extensive fat
content (50-95%)and small amounts of thin fibrous septa
• DD are cardiomegaly, epicardial fat, pericardial cyst.

21. Cystic
masses
• 15-20 %
• Middle mediastinum, MC
• smooth walled,
homogenous attenuation,
non enhancing lesions,
with no infiltration
• Sometimes have
calcification, proteinaceous
or mucinous contents
• MRI  T2 , high signal
intensity
• Bronchogenic cysts
• Congenital, tracheobronchial tree origin
• 40% symptomatic
• mc located near carina or paratracheal
area.
• Duplication Cyst
• Congenital, GI origin
• Mostly asymptomatic,
• Mediastinal neuroenteric
cysts
• anomalous protrusions of the
leptomeninges through intervertebral
foramen or defects in the vertebral body.
• They are associated with multiple vertebral
anomalies and with neurofibromatosis
• Pericardial Cyst
• 5-10 % primary Ms masses
• unilocular
• MC site  right CP space
• Thymic Cyst
• 1% of Primary Ms masses
• congenital (unilocular) or acquired
(multilocular, thymoma/lymphoma/GCT)
• Lymphangioma
• 1-2% of Primary Ms masses

22. Thymoma
Clinical clues
• 40-50 % of MM
• 40-60 years
• a/w MG 30-50%.
• Hypo GG nemia 5%.
• PRCA 5%.
• 50% incidental.
• 35% invasive also.
• S Ach R Ab titre.
Radiological clues
• Ant Ms, AP window.
• Well defined encapsulated
homogenous mass.
• May appear heterogeneous
due to necr/Hg/cyst
changes
• Punctate, ring like
calcification 20%
• LN always Neg
• Rarely infiltrative
• CT helps to Diff Thymic
Hyperplasia.

23. Thymic Carcinoma
• 50+
• Uncommon
• Symptomatic often.
• MG never seen
• Infiltrating mass, with Blood vessel invasion
• LN+ high.
• May be Pleural nodules and lung mets.
• More cystic/necrotic component.
• Rarely Thymic Carcinoid or thymolipoma, Dx is by Tissue Dx.
• Thymic cyst
• Thymic hyperplasia.

24. Lymphoma
Clinical clues
• Ant > middle > post
• Secondary > HD > NHL
(85%/15%)
• Bimodal distribution
(20/50+)
• 20-30% of MM
• 20-30% have B symptom
• A/W Gen LAP
Radiological clues
• Homogenous, enhancing,
lobualated but infiltrative
masses
• Pleural effusion and LN
+

25. Thyroid
Clinical clues
• Middle age.
• F >> M.
• 10% on MM.
• Calcification 25%.
• Can be cervical goiter
with retrosternal
extension or >>
goiter/tumor of
ectopic/remnant thyroid.
Radiological clues
• Enhancing, Inhomogenous
lobulated, encapsulated mass,
with areas of
calcification/cystic
degeneration.
• Thyroid cancer  infiltrative
and LN+.
• Can be diagnosed without
biopsy by Radioactive iodine
scan.
• No treatment unless
symptomatic, usually pressure
symptoms or malignancy.

26. Germ Cell Tumor
• Ant Ms is MC site of Extra
gonadal GCTs.
• 15 % of all Anterior Ms
Masses in adults
• 25-30% of all ant ms
masses in Children.
• MC age 30-40 for SGT, 15-
30 For NSGCT.
• Less commonly seen in
Post Ms.
• NSGCT (Teratoma MC
type) >> SGT
• Uncommon
• Large
heterogeneous
infiltrative masses
• Areas of necrosis
and Hg
• Pleural &
pericardial
Effusion common.
• Seminoma too are
like NSCGCT
Other NSGCT/Seminoma

27. Teratoma
Clinical clues
• Young < 30 years
• Mature teratoma
benign
• 70% of GCT
• CXR  large lobulated,
well-circumscribed
protrude into one lung
field.
Radiological clues
• CT heterogeneous
anterior Ms mass
• Fluid-containing cystic
areas, fat, and
calcification occur
frequently.
• The findings of fat and
fluid levels produced
by high lipid content in
the cyst fluid are
diagnostic

28. Imaging
• MRI has certain indication
• It better delineate soft
tissue and vascular
involvement.
• Its better differentiate solid
from Cystic masses.
• Available for patient of
contrast allergy.
• For intraspinal ext. of post
Ms tumors.
PET is not standard, May be used for
• differentiating thymoma
from hyperplasia in
myasthenia gravis
• useful for predicting the
grade of malignancy in
thymic epithelial tumors.
CXR, often available but hardly informative
CECT chest is Imaging Modality of Choice,

29. • Radioisotope scanning has been of specific aid in
establishing a definitive diagnosis for ectopic thyroid and
parathyroid tumors.
• Infants and child  Paravertebral mass,
• Norepinephrine and epinephrine level. (NB & gNB)
• Young adult Ant ms mass
• b HCG, LDH and AFP
• Anterior MS mass with suspected thymoma (>40yr A
mm)
• S Ach R Ab titre
• S soluble IL 2 level elevated in Ms Lymphoma.
• Thymic carcinoids produce  ACTH & Cortisol 
hypokalmia.

30. Neurogenic tumors
• Posterior Ms
• 20% of Ms mass adults/ 35% child.
• Originate in neural crest
• Mostly benign and asymptomatic. 70-80%
Peripheral nerve tumors  70%
• schwannomas (Benign), MC
• Neurofibroma  nonencapsulated (benign)
• Neurilemmoma –: “Dumb bell Tumor”, neural sheath origin
• SG tumors  25%
• Ganglioneuroma
• Ganglineuroneurobalstoma.
• Paraganglia- paraganglioma (rare/benign)

31. Schwannoma
• Post M
• 20-30 year
• Incidental, symptomless
• CT  well defined,
Markedly convex mass
• Dumbbell/ hourglass
configuration
• Cystic/ hmg/ calcifi
common.
• Multiple lesion  NF2
SGT
• Post MM
• Child/ young adult
• Well defined/ill defined
mass
• Oriented along AL
surface of several
vertebrae
• Whorled appearance.

32. Paraganglioma
•Aortopulmonary Paraganglioma 
• asymtomatic, 40+
•Aortosymphathetic Paraganglioma
• Young, often Symptomatic
•Enhancing hyper vascular tumors.
•Salt pepper appearance on MRI.

33. Conclusion
• MM are diverse and management depend on exact Dx
• CT is IOC.
• MRI may used as problem solving modality and adds value
sometimes.
• Role of PET CT is not well defined.
• Biopsy is Often Required before Definitive Mx.
• Bx options are many and best option should be chosen
according individual case to case basis.