11.21.08 proctor. schwannoma

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Evaluation ofMediastinal Mass

Leslie Proctor, M.D.

November 21, 2008


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The differential diagnosis of a mediastinal mass depends upon the anatomic compartment in which it arises.Redrawn from Baue, AE, et al. Glenn's Thoracic and Cardiovascular Surgery. 5th ed. Appleton & Lange,Norwalk, CT, 1991.


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Mediastinal Anatomy Anterior Compartmentincludes:

ThymusExtrapericardial aorta and its branches

The great veinsLymphatic tissue.

Middle Compartment is bounded by:

The pericardium anteriorly The posterior pericardial reflection The diaphragm The thoracic inlet. This compartment includes the heart,intrapericardial great vessels,pericardium, and trachea.

Extends from the posterior pericardial reflection to the posteriorborder of the vertebral bodies and from the first rib to thediaphragm.

It includes the esophagus, vagus nerves, thoracic duct, sympatheticchain, and azygous venous system

Posterior Compartment:


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Anatomic Distribution of Masses

Anterior Mediastinum

Thymic tumors and cystsGerm cell tumors

LymphomasIntrathoracic goiter andthyroid tumorsParathyroid adenomasConnective tissue tumors

- lipomas and liposarcomas- lymphangiomas- hemangiomas

Thymoma


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Middle Mediastinum

Thyroid tumor or goiter Tracheal tumors

Aortopulmonaryparaganglioma

paracardial cystsbronchogenic cysts

lymphomaLymphadenopathy

Retrosternal Goiter


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Posterior MediastinumNeurogenic tumors

including Schwannomas

Esophageal tumorsHiatal HerniasNeurenteric Cysts

And rarely extramedullary hematopoiesispancreatic pseudocystachalasia

Paraspinal Ganglioneuroma


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About Neurogenic tumors 9 to 39 percent of all mediastinal tumorsdevelop from mediastinal peripheral nerves, sympathetic and parasympathetic ganglia, and embryonic remnantsof the neural tube.most frequent in the posterior compartment of the mediastinumCan cause neurologic symptoms by compression.Benign Schwannoma is most common

often asymptomatic, but can be associated with Horners or Pancoasts syndrome Focal calcifications and cystic changescan extend through an intervertebral foramen, resulting in dumbbell-shaped tumors, and neurologicsymptoms of spinal cord compressionGross Histology

encapsulated, solid, soft, yellow-pink nodule, with the capsule attached to the epineurium of thenerve that gives rise to the neoplasm

Microscopic histologycomposed of spindle cells with elongated nuclei, forming interlacing bundles with focal nuclearpalisadingnuclear atypia, and stromal sclerosis in older lesionsMitotic figures are rare.Immunohistochemical studies reveal a strongly positive reaction with S-100 protein.


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A mass may extend beyond these boundaries asit grows in sizeIn adults, anterior compartment masses aremore likely to be malignant


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Age Distribution

Age can help predict etiology of the massinfants and children, neurogenic tumors and enterogenouscysts are the most common mediastinal masses

In adults, neurogenic tumors, thymomas, and thymic cysts aremost frequently encountered lesionsIn 20-40 year olds, the likelihood of a mass being malignant isgreater secondary to the increased incidence of lymphoma

(Hodgkins and non -Hodgkin's) and germ cell tumors


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Signs and Symptoms

Depend on location ofmass

Asymptomatic

Vague symptomsaching paincough

Children more likely to be

symptomaticrespiratory difficultyrecurrent pulmonaryinfections


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Signs and Symptoms

Airway compressionrecurrent pulmonary infectionhemoptysis

Esophageal compressiondysphagia

Involvement of the spinalcolumn

paralysis

Phrenic nerve damageelevated hemidiaphragm


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Signs and Symptoms

Recurrent laryngeal nerveinvolvement

Hoarseness

Sympathetic ganglioninvolvement

Horners Syndrome Ptosis, miosis, anhidrosis

superior vena cava

involvementSuperior vena cava syndrome

facial neck, and UE swelling,dyspnea, chest and UE pain,mental status changes

Horners Syndrome


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Signs and Symptoms

Can also be associated with systemic diseases Thymoma: myasthenia gravis, immune deficiency,red cell aplastic anemiaGoiter: thyroxicosis

Thymic carcinoid: Cushings syndrome Parathyroid: hyperparathyroidism


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Evaluation: Imaging2 view PA/Lat Chest X-ray

comparisons with old x-rays importantChest CT with contrast

most important method of evaluationCan help determine location, morphology, size, and attenutation coefficientImportant for directing further therapy

MRI when contrast allergy or renal failure present when vascular or chest wall involvement is suspectedneurogenic tumors (especially helpful in detecting intraspinal component

UltrasoundDifferentiate cystic from solid masses and relate to surrounding structures

When mass is close to heart or pericardium Transesophageal or transbronchial useful to evaluate lymph nodes, sometimes for biopsy

Radio nucleotide scanning With radioactive iodine when thyroid tumor suspected

PET scanningCan localize specific tumors (pheochromocytoma, paragangliomas, neuroblastomas, neurogangliomas bytargeting their metabolic pathways


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Evaluation: Laboratory

Depends on clinic setting, but may include: Thyroid function tests

If goiter suspectedChemistry panel including calcium and phosphate and PTH

If parathyroid adenoma suspectedFractionated 24-hour urinary metanephrines and catecholamines

If paraganglionic tumor suspected AFP/beta HCG

In all males with anterior mediastinal tumor because of concern fornon-seminomatous germ cell tumor


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Management Tailored to specific or likely diagnosisMust decide whether to excise, biopsy,or aspirate lesion

Excision should be done withteratomas, thymomas, and isolatedmasses likely to be benign (VATS,median sternotomy, thoracotomy)Needle aspiration of cystic lesionsDiagnostic biopsy is procedure ofchoice when suspect lymphoma,

germ cell tumor, or unresectableinvasive malignancy


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ReferencesKallab, Andre MD. Superior Vena Cava Syndrome. Emedicine. August 10 2005.http://www.emedicine.com/MED/topic2208.htm

Gangadharan, Sidhu MD. Evaluation of Mediastinal Masses. UptoDate. October 7, 2008.

Parmar, Malvinder S, MB, MS. Horners Syndrome. Emedicine. June 5, 2008.http://www.emedicine.com/med/TOPIC1029.HTML

Strolls, DC, Rosado-de-Christenson, ML, Jett, JR. Primary mediastinal tumors. Part I: Tumors of the anterior mediastinum. Chest1997; 112:511.

Strollo, DC, Rosado-de-Christenson, ML, Jett, JR. Primary mediastinal tumors: Part II. Tumors of the middle and posteriormediastinum. Chest 1997; 112:1344.

Medscape.com (multiple images)

Devouassoux-Shisheboran, Mojgan MD and Travis, William D MD. Pathology of Mediastnal Tumors. Uptodate. September 9 th,2008.
http://www.emedicine.com/MED/topic2208.htmhttp://www.emedicine.com/med/TOPIC1029.HTMLhttp://www.emedicine.com/med/TOPIC1029.HTMLhttp://www.emedicine.com/MED/topic2208.htm

11.21.08 proctor. schwannoma

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