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Neoplasms of the mediastinum

The neoplasms of the mediastinum are of different origins which include:
  • Neurogenic (21%)
  • Thymomas (19%)
  • Primary cysts (18%)
  • Lymphomas (13%)
  • Germ cell tumors (10%)
Each neoplasm has its own specific anatomic site in the mediastinum e.g. neurogenic, germ cell tumors and lymphomas are usually found in the posterior mediastinum, thymomas, lymphomas and germ cell tumors are usually located in the anterior and superior mediastinum but cysts and lymphomas are only found in the middle mediastinum.

Malignancy is also represented with different figures in each subdivisions of mediastinum e.g.
  • Anterior superior (59%)
  • Middle (29%)
  • Posterior (16%)
Signs and Symptoms:
The main symptoms of malignant tumors are fever, cough, chest pain and myasthenia gravis (sign of thymomas).

Diagnosis:
Diagnostic procedures include ultrasound, CT, MRI, monoclonal antibody test and fine needle biopsy.

Neurogenic Tumors:
Neurogenic tumors are commonly benign and are located near the paravertebral ganglia in the posterior medistinum. They have 3 sources of origination:
  • From lymphatic ganglia originate gangliomas, ganglioneuroblastomas and neuroblastomas
  • From internal costal nerve originate neuroleomyomas, neurofibromas and nerosarcomas
  • From paraganglia originate paragangliomas and are quite rare
Most encountered neurogenic tumor is neurilemoma which arises from the Schwann cells of the nerve sheath. Paragangliomas is some causes produce catecholamines especially norepinephrine and in this case high arterial pressure, weight loss and hyperhydrosis are specific signs encountered.

Germ Cell Tumors:
Germ cell tumors arise from primary primordial cells and usually they have teratomas, seminomas and teratosarcomas. Teratodermoid is the simplest form of teratomas. In many cases it includes some ectodermal elements such as hair, bone, teeth etc.

Primary cysts:
Primary cysts are bronchogenic pericardial and enteric.

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This article has been written by Dr. M. Javed Abbas.
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12:14 08/02/2003