Mediastinal Tumours

Question 1

What is the mediastinum?

Answer 1

An area which contains all of the structures of the thorax except lungs and pleura. Also contains lymph nodes, small vessels, nerves, adipose tissue to the commonly thought of constituents of thymus, thyroid, parathyroid, oesophagus, trachea, heart, pericardium, great vessels.

Question 2

List the contents of the superior mediastinum.

Answer 2

thymus, thyroid, parathyroid, great vessels, oesophagus, trachea, thoracic duct.

Question 3

List the contents of the posterior mediastinum.

Answer 3

inferior thoracic vertebrae, thoracic nerves, descending thoracic aorta, oesophagus.

Question 4

List the contents of the central or middle mediastinum.

Answer 4

pericardium, heart, great arteries, phrenic nerves, main bronchi.

Question 5

List the contents of the anterior mediastinum.

Answer 5

In infancy, the thymus.

Question 6

List two common tumours of the superior mediastinum.

Answer 6

Lymphoma, thymoma.

Question 7

Contrast a thymoma to thymic carcinoma

Answer 7

A thymoma is well differentiated with no cellular atypia, whereas a thymic carcinoma is poorly differentiated with cellular features of malignancy.

Question 8

What is the pathophysiology of myasthenia gravis? How does is often present? What is involved in treatment?

Answer 8

Myasthenia gravis is an autoimmune disease of the neuromuscular junction, where there are circulating antibodies to acetylcholinesterase receptors. This weakens muscle power, often presenting with muscle fatigue, droopy eyelids and double vision, progressing to death from respiratory failure. Treatment involved anticholinesterase drugs, steroids, and resection of thymoma. (65% of cases associated with thymic hyperplasia, 15% with thymoma)

Question 9

Compare and contrast Hodgkin to non-Hodgkin lymphomas.

Answer 9

Both normally B cell origin but can be from T cells.
Hodgkin lymphomas have Reed-Sternberg cells in histology, and spread in an orderly fashion, so are potentially curable with localised treatment. Express CD15 and CD30.
Non-Hodgkin lymphomas have systemic spread therefore require systemic treatment and are progressive diseases.

Question 10

List the steps in the diagnosis of a lymphoma.

Answer 10

clinical picture, biopsy, morphology under M/S, immunohistochemistry, cytogenetics, molecular studies.

Question 11

How are mediastinal germ cell tumours classified?

Answer 11

Teratomatous and non teratomatous lesions.
Non-teratomatous includes seminoma, yolk sac, choriocarcinoma, and embryonal carcinoma.
(NOTE: this is different to testicular, where it is seminomatous and non seminomatous)