4.4 Mediastinal tumours Flashcards
What is the mediastinum?
All the structures of the thorax except the lungs and the pleura
The structures are surronded by loose connective tissue and can accommodate movement
What are the compartments of the mediastinum?
Superior, inferior (anterior, middle and posterior)
What are the borders of the mediastinum?
Superior thoracic aperture, sternum, diaphragm and thoracic vertebrae
What is in the superior mediastinum?
Thymus, thyroid, parathyroid, great vessels, oesophagus, trachea, thoracic duct
What is in the posterior mediastinum?
Inferior thoracic vertebrae, thoracic nerves, descending thoracic aorta
What is in the middle mediastinum?
Pericardium, heart, great arteries, phrenic nerves, main bronchi
What is in the anterior mediastinum?
In children contains the thymus
What are the common tumours of the mediastinum?
Thymoma, lymphoma and germ cell tumours
Where do you find thymoma?
Anterior superior mediastinum
What does the thymus develop from?
3rd and 4th pharygeal pouch
What is the weight of the thymus?
Birth: 15g
Pubetry: 40g
>60: 10 g
What is a thymoma?
Tumour arising from the thymic epithelial cells
Can a thymoma invade or metastasise?
Can locally invade but cannot metastasise
What is the presentation of thymoma?
Adults >40 Incidental discovery Local pressure symptoms Myastheia gravis (in up to 50%) Mass lesion in anterior superior mediastinum
What is used for diagnosis of thymomoa?
CXR, CT (suggestive)
Percutaneous biopsy - cytology
Mediastinoscope and biopsy - histology
What is the micro appearance of thymoma?
Fibrous tissue dividing the tumour into lobules
Few epithelial cells
Immature T lymphocytes
What is the classification of thymoma?
Thymoma: well differentiated with no cellular atypia
Thymic carcinoma: poorly differentiated with cellular features of malignancy
What is the treatment of thymoma
Depends on extent and cell type
Primary: complete surgical removal and radiotherapy
Non resectable: palliative radiotherapy and chemo
What is Myasthenia Gravis?
An autoimmune disease where there are circulating antibodies to ACh blocking the receptors
Affects females > males
What is the manifestation of myasthenia gravis?
Weakness of extra ocular eye muscles (droopy eyelids and double vision)
Muscle power decreasing with use
What is Myasthenia gravis associated with?
65% with thymic hyperplasia
15% with thymoma
What are Non Hodgkin lymphomas comprised of?
T or B cells (85% B cell) - MONOCLONAL
What is the spread of hodgkin and non hodgkin lymphoma?
Hodgkin: Systemic spread - systemic treatment
Non: Orderly spread - local treatment
What is used for diagnosis of lymphoma?
Haematoxylin and eosin stain
Immunohistochemistry for cell differentiation and type
Cytogenetics for chromosomal abnormalities
How do you differentiate B and T cells?
B = CD20 T = CD3
What markers will you see in hodgkins lymphoma?
CD15 and CD30
What translocation do you see in follicular lymphoma?
t(14;18)leading to expression of bcl-2 which is an anti apoptotic gene
What is the usual presentation of mediastinal germ cell tumours?
Men 10-30
Anterior superior mediastinum
Symptoms due to compression
What are the different types of germ cell tumours and which are most common in the mediastinum?
Teratomatous: mature teratoma, immature
Non teratoma: seminoma, yolk sac tumour, chorioacinoma, embryonal carcinoma
Teratoma > seminoma > others
What is the most aggressive mediastinal germ cell tumour?
Non teratomatous (mature teratoma = benign)
