Posterior mediastinal lesions

1. Posterior Mediastinal Lesions
Alireza Kashani

2. Mediastinal Compartments
 Posterior Mediastinum:
 Also called paravertebral
compartment
 Defined by :
 Posterior Pericardium
 Anterior Spinal Ligament
 Superiorly: T4 vertebral body
 Inferiorly: Diaphragm
 Contains:
 Oesophagus, Descending Aorta,
Sympathetic Chain, Vagus
Nerves, Thoracic Duct, Azygos
and Hemiazygos veins, and
Lymph Nodes

3. Epidemiology
 Adults:
 65% anterosuperior
 10% middle
 25% posterior compartments
 Children:
 25% anterosuperior
 10% middle
 65% in posterior compartments
 Generally the incidence of posterior mediastinal lesions is higher in children.
 50% are asymptomatic and are diagnosed incidentally
 The absence of symptoms is generally is a clue to a benign lesion
 Symptomatic lesions:
 Children: 60%-80%
 Adults: 50%-60%

4. Diagnosis
 CT Scan is the diagnostic modality of choice and is superior to even MRI in
majority of the cases
 MRI rarely indicated
 Thoracic US is not helpful in posterior mediastinal lesions
 Biopsy: is not necessary in majority of the cases and likelihood of a positive
result parallels the presence of symptoms
 If needed:
 CT-guided
 Thoracoscopic
 Limited posterolateral thoracotomy

5. Neurogenic Tumours
 Young adults and children
 They are the most common malignant neoplasm in children but they are less
common than anterior mediastinal malignancies in adults.
 Lymphomas and Thymomas are more common in adults
 Malignancy rate:
 Children: 50%
 Adults: 10%
 They originate from embryonic neural crest cells around the spinal ganglia
and from either sympathetic or parasympathetic components

6. Neurogenic Tumours
 Source:
 Intercostal nerve:
 Neurofibroma : benign
 Of patients with nerve sheath tumours 25%-40% have multiple
neurofibromatosis (von Recklingausen’s disease) and the incidence of
malignancy is more common in these patient
 Neurilemoma (Schwannoma) :
 Mostly benign but malignant schwannomas are rare
 The most common neurogenic tumor
 Neurogenic Sarcoma (rare)
 Sympathetic Ganglia: can also have pheochromocytoma
 Ganglioneuroma
 Ganglioneuroblastoma
 Neuroblastoma
 Other: phrenic nerves, Vagus nerves

7. Neurogenic Tumours
 Those with benign lesions are generally asymptomatic
 Malignant tumors might present with symptoms such as:
 Spinal cord compression
 Cough
 Dyspnea
 Chest wall pain
 Hoarseness
 Rarely Horner’s syndrome
 Rarely pheochromocytoma:
 Neuroblastoma or ganglioneuroma
 In all symptomatic patients, esp. those with significant hypertension it is
necessary to check for 24 h urine HVA (homovanillic acid) and VMA
(vanillylmandelic acid)
 If elevated then prior to operation to avoid adrenergic crisis:
 α-adrenergic blockers
 beta-blockers

8. Neurogenic Tumours
 Intercostal nerves:
 Neurofibroma
 Poorly encapsulated
 Random arrangement of spindle-shaped cells
 Neurilemomas
 The most common neurogenic tumor
 Well-encapsulated
 Firm, gray-tan
 Two morphologic types:
 Antoni’s type A:
 Organized architecture with a cellular palisading pattern of growth
 Antoni’s type B:
 Loose reticular pattern
 Both of the above can happen as parts of neurofibromatosis type 1 (von
Recklinghausen’s disease) and if left untreated can degenerate to neurosarcoma

9. Neurofibroma

10. Neurilemmoma – Mixed A and B

11. Neurilemmoma – Antoni A

12. Neurilemmoma – Antoni B

13. Sympathetic Source

14. Sympathetic Source
 Neuroblastic Tumors:
 Arising from primitive sympathetic
ganglia
 Comprise:
 Neuroblastoma
 Ganglioneuroblastoma
 Ganglioneuroma
 These differ in their degree of cellular
and extracellular maturation
 Immature tumors:
 Tend to be aggressive
 Occur in younger patients
(median age < 2)
 Mature tumors:
 Older children (median age 7)
 More benign
 Anywhere sympathetic nervous
tissue exists:
 Neck
 Posterior Mediastinum
 Adrenal Gland
 Retroperitoneum
 Pelvis

15. Sympathetic Source
 Ganglioneuroma:
 The most common neurogenic tumor occurring in children
 Benign
 Composed of gangliocytes and mature stroma
 Early age
 Located in the paravertebral region
 Ganglioneuroblastoma:
 Composed of mature gangliocytes and immature neuroblasts
 Intermediate malignant potential

16. Ganglioneuroma

17. Ganglioneuroma

18. Sympathetic Source
 Neuroblastoma:
 Children < 4 y
 Small, round immature cells organized in rosette pattern
 Highly invasive
 Metastasized by the time the diagnosis is made:
 Regional lymph nodes, bone, brain, liver, lung
 Some may have benign course
 Symptoms:
 Cough, dysphagia, chest pain, and occasionally paraplegia
 Paraneoplastic:
 Profuse watery diarrhea due to VIP
 Opsoclonus-Polymyoclonus syndrome
 Pheochromocytoma-like syndrome
 Prognosis:
 Influenced by: DNA content, tumor proto-oncogenes, and catecholamine synthesis
 The above aid in categorizing patients with neuroblastoma into low, intermediate,
and high-risk
 Rx: Resection +/- Chemotherapy

19. Neuroblastoma

20. Neuroblastoma

21. Investigations
 CT:
 Can help to identify the tumor and extent of involvement
 Those from peripheral nerves:
 Well-defined, round or oval masses
 Noncalcified
 Neurilemoma:
 Variable enhancement: homogenous or heterogenous
 On enhanced CT: variable attenuation
 Neurofibroma:
 Usually homogenous
 Low-attenuation
 On enhanced CT: homogenous enhancement or with early central blush
 Malignant nerve sheath tumors show variable attenuation

22. Investigations
 CT:
 Sympathetic Chain Tumors:
 Expand along the spinal axis
 No calcification or bone changes
 Ganglioneuroma:
 Oblong homogenous low-attenuation lesions on both enhanced and
unenhanced CT
 Neuroblastoma:
 Aggressive soft tissue lesions with calcification
 Ganglioneuroblastoma:
 Mixed features of above
 Paragangliomas:
 Appear in aortopulmonary window
 High contrast enhancement

23. Investigations
 MRI: for dumbbell tumors
 FNA
 Tumor Markers: S-100

24. Dumbbell Tumors
 Tumors of the posterior mediastinum
that extend into the spinal canal via
the intervertebral foramen
 It is necessary to identify these
tumors to have a better planning, as
inaccurate diagnosis would lead to
intra-spinal hemorrhage and cord
compression
 MRI can identify these
 Smoothly rounded, homogenous
density abutting the vertebral column
 Rarely present with cord
compression symptoms
 They comprise 10% of patients with
neurogenic tumors
 Only 1-2% are malignant

25. Management
 Standard of Care:
 Surgical resection via thoracotomy or thoracoscopy
 Most of the neurogenic tumors can be resected via thoracoscopy; however, malignant
transformation, local invasion, and tumors larger than 5 cm increase the likelihood of
conversion to thoracotomy
 In most cases the tumor can easily be mobilized via thoracoscopy but any difficulty
necessitates the conversion to thoracotomy
 Resection of the nerve root is necessary in most of the cases
 A widened intervertebral foramen might be indicative of invasion of vertebral canal
(dumbbell tumor) and in these cases it is necessary to involve a neurosurgeon to
assist in full resection of the tumor via a laminectomy in one stage procedure
 Neuroblastoma:
 Spontaneous regression has been reported
 Stage:
 I (noninvasive): Surgical resection alone
 II (locally invasive on same side of midline): Surgery + RTx
 III (invasive across the midline): Debulking + RTx + ChemoTx + Second-look
operation
 Children < 1 : good prognosis, prognosis has inverse correlation with age

26. Oesophageal Masses
 These include:
 Neoplasm
 Cysts
 Diverticula
 Hiatal Hernia
 Mega-oesophagus
 Oesophageal Varices

27. Cysts
 Rare, benign, congenital
 20% of all mediastinal lesions
 Include:
 Bronchogenic
 Hydatid
 Enteric
 Intramural Oesophageal
 Neuroenteric Cysts
 CT is the most effective modality of diagnosis

28. Bronchogenic
 60% of all mediastinal cysts
 Location:
 Lung parenchyma
 Mediastinum
 Histology:
 Ciliated columnar epithelium
 Cyst wall: cartilage, mucus glands,
smooth muscle
 Rarely communicate with the
tracheobronchial tree
 Symptoms:
 Occasional compression on the
adjacent structures
 Recurrent infection
 Pain, Cough, Hemoptysis
 Rx:
 If incidental finding in an otherwise
asymptomatic patient: observation is
accepted
 If symptomatic esp. if pain, cough, or
hemoptysis the resection is strongly
advised.

29. Bronchogenic

30. Bronchogenic

31. Bronchogenic
 Dysphagia: as a result of
compression effect on the
oesophagus
 Presence of air-fluid level: suggests
the possibility of communication with
the tracheo-bronchial tree and
increased chance of recurrent
infections; hence, the possible need
for resection
 If it becomes infected, it is very likely
that eradication is unsuccessful and
it needs to be resected
 Symptoms tend to develop with time
and hence the resection is advised
in a healthy state before becoming
symptomatic.
 They can be resected via
thoracoscopy or if in superior
mediastinum via mediastinoscope.

32. Bronchogenic

33. Bronchogenic

34. Gastroenteric Cysts
 Gastroenteric or duplication cysts:
peri-oesophageal lesions that arise
from posterior division of the primitive
foregut.
 Features:
 Posterior or middle mediastinal mass
 Within or adjacent to the oesophageal
wall
 Communication with UGIT is
uncommon
 Histology:
 Nonkeratinizing squamous, ciliated
columnar, gastric, or small intestinal
epithelium
 Epithelium is not a good differentiating
feature from bronchogenic cysts:
 Presence of two muscular layers in
oesophageal cysts
 Cartilage and bronchial glands in
bronchogenic cysts
 Usually asymptomatic, but symptoms:
 Resp: Cough, SOB, Recurrent
Pulmonary Infections, Chest Pain
 If gastric mucosa: perforation into the
oesophagus can cause haematemesis,
or erosion into the adjacent lung can
cause an abscess
 Dx: EUS, Chest CT, Technetium Tc
99m (to identify gastric mucosa)
 Rx:
 Resection: symptomatic, unclear cysts
– whether cystic or solid
 Observation: clearly cystic lesions,
otherwise asymptomatic

35. Gastroenteric Cysts

36. Gastroenteric Cysts

37. Neuroenteric Cysts
 5-10% of foregut lesions
 Infants younger than 1
 Connection to the meninges usually through a stalk
 Associated with the congenital defects of the spine
 Endodermal and ectodermal or neurogenic elements
 Failure of separation of the notochord from the primitive gut
 CT evidence of mediastinal lesion with either of : Scoliosis, Hemivertebrae,
Spina Bifida should prompt the possible Dx of neuroenteric cysts.

38. Other
 Primary or metastatic lesions of
thoracic spine
 Lymphomas : esp. Hodgekins
 Infections such as TB
 Post-traumatic haematoma
 Descending thoracic aneurysm
 Extramedullary hematopoiesis
 Castleman’s Disease
 Angiomyolipoma
 Extralobar Pulmonary Sequestration
 Neuroendocrine Carcinoma
 Mediastinal Ependymoma
 Cellular Hemangiomas
 Melanotic Paraganglioma
 Pancreatic Pseudocyst Mediastinal
Extension

39. Castleman’s Disease
 Giant lymph node hyperplasia
 Vascular tumors surrounded by
large LAP
 Types :
 Localized: Hyaline Vascular, Plasma
Cell
 Generalized or Multicenteric
 Hyaline Vascular: 90% of lesions
 Incidental finding in otherwise
asymptomatic
 Spinal cord compression has also
been reported
 Rx: Surgical excision, RTx is
ineffective
 Plasma Cell:
 More symptomatic: fever, fatigue,
weight loss, hemolytic anemia, high
ESR and hyper-γ- globulinemia as
the result of the over production of
IL-6
 Resection is Rx of choice
 Generalized:
 Histologic features of both of the
localized forms
 Older patients
 Symptoms:
 Severe systemic symptoms
 Generalized LAP
 Hepatosplenomegaly
 Mortality : 50% with median survival
of 27 months and Progression to
lymphoma

40. Castleman’s Disease - Hyaline

41. Castleman’s Disease - Plasma