4.4 Mediastinal tumours Flashcards

1
Q

What is the mediastinum?

A

All the structures of the thorax except the lungs and the pleura
The structures are surronded by loose connective tissue and can accommodate movement

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2
Q

What are the compartments of the mediastinum?

A

Superior, inferior (anterior, middle and posterior)

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3
Q

What are the borders of the mediastinum?

A

Superior thoracic aperture, sternum, diaphragm and thoracic vertebrae

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4
Q

What is in the superior mediastinum?

A

Thymus, thyroid, parathyroid, great vessels, oesophagus, trachea, thoracic duct

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5
Q

What is in the posterior mediastinum?

A

Inferior thoracic vertebrae, thoracic nerves, descending thoracic aorta

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6
Q

What is in the middle mediastinum?

A

Pericardium, heart, great arteries, phrenic nerves, main bronchi

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7
Q

What is in the anterior mediastinum?

A

In children contains the thymus

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8
Q

What are the common tumours of the mediastinum?

A

Thymoma, lymphoma and germ cell tumours

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9
Q

Where do you find thymoma?

A

Anterior superior mediastinum

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10
Q

What does the thymus develop from?

A

3rd and 4th pharygeal pouch

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11
Q

What is the weight of the thymus?

A

Birth: 15g
Pubetry: 40g
>60: 10 g

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12
Q

What is a thymoma?

A

Tumour arising from the thymic epithelial cells

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13
Q

Can a thymoma invade or metastasise?

A

Can locally invade but cannot metastasise

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14
Q

What is the presentation of thymoma?

A
Adults >40 
Incidental discovery 
Local pressure symptoms 
Myastheia gravis (in up to 50%) 
Mass lesion in anterior superior mediastinum
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15
Q

What is used for diagnosis of thymomoa?

A

CXR, CT (suggestive)
Percutaneous biopsy - cytology
Mediastinoscope and biopsy - histology

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16
Q

What is the micro appearance of thymoma?

A

Fibrous tissue dividing the tumour into lobules
Few epithelial cells
Immature T lymphocytes

17
Q

What is the classification of thymoma?

A

Thymoma: well differentiated with no cellular atypia

Thymic carcinoma: poorly differentiated with cellular features of malignancy

18
Q

What is the treatment of thymoma

A

Depends on extent and cell type

Primary: complete surgical removal and radiotherapy

Non resectable: palliative radiotherapy and chemo

19
Q

What is Myasthenia Gravis?

A

An autoimmune disease where there are circulating antibodies to ACh blocking the receptors

Affects females > males

20
Q

What is the manifestation of myasthenia gravis?

A

Weakness of extra ocular eye muscles (droopy eyelids and double vision)
Muscle power decreasing with use

21
Q

What is Myasthenia gravis associated with?

A

65% with thymic hyperplasia

15% with thymoma

22
Q

What are Non Hodgkin lymphomas comprised of?

A

T or B cells (85% B cell) - MONOCLONAL

23
Q

What is the spread of hodgkin and non hodgkin lymphoma?

A

Hodgkin: Systemic spread - systemic treatment
Non: Orderly spread - local treatment

24
Q

What is used for diagnosis of lymphoma?

A

Haematoxylin and eosin stain
Immunohistochemistry for cell differentiation and type
Cytogenetics for chromosomal abnormalities

25
Q

How do you differentiate B and T cells?

A
B = CD20 
T = CD3
26
Q

What markers will you see in hodgkins lymphoma?

A

CD15 and CD30

27
Q

What translocation do you see in follicular lymphoma?

A

t(14;18)leading to expression of bcl-2 which is an anti apoptotic gene

28
Q

What is the usual presentation of mediastinal germ cell tumours?

A

Men 10-30
Anterior superior mediastinum
Symptoms due to compression

29
Q

What are the different types of germ cell tumours and which are most common in the mediastinum?

A

Teratomatous: mature teratoma, immature

Non teratoma: seminoma, yolk sac tumour, chorioacinoma, embryonal carcinoma

Teratoma > seminoma > others

30
Q

What is the most aggressive mediastinal germ cell tumour?

A
Non teratomatous 
(mature teratoma = benign)