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2. 3. 4. 5. Evaluation of Mediastinal Mass Leslie Proctor, M.D. November 21, 2008 6. Mediastinal Anatomy

Includes structures bound by:

• the thoracic inlet

• diaphragm

• sternum

• vertebral bodies

• and pleura

Has 3 compartments

• Anterior

• Middle

• Posterior

7. 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. 8. Mediastinal Anatomy

Anterior Compartment includes:

Thymus

Extrapericardial aorta and its branches

The great veins

Lymphatic 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: 9. Anatomic Distribution of Masses

Anterior Mediastinum

Thymic tumors and cysts

Germ cell tumors

Lymphomas

Intrathoracic goiter and thyroid tumors

Parathyroid adenomas

Connective tissue tumors

• lipomas and liposarcomas

• lymphangiomas

• hemangiomas

Thymoma

10. Anatomic Distribution of Masses

Middle Mediastinum

Thyroid tumor or goiter

Tracheal tumors

Aortopulmonary paraganglioma

• paracardial cysts

• bronchogenic cysts

• lymphoma

Lymphadenopathy

Retrosternal Goiter

11. Anatomic Distribution of Masses

Posterior Mediastinum

Neurogenic tumors

• including Schwannomas

Esophageal tumors

Hiatal Hernias

Neurenteric Cysts

And rarely

• extramedullary hematopoiesis

• pancreatic pseudocyst

• achalasia

Paraspinal Ganglioneuroma

12. About Neurogenic tumors

9 to 39 percent of all mediastinal tumors

develop from mediastinal peripheral nerves, sympathetic and parasympathetic ganglia, and embryonic remnants of the neural tube.

most frequent in the posterior compartment of the mediastinum

Cancause neurologic symptoms by compression.

Benign Schwannoma is most common

• often asymptomatic, but can be associated with Horners or Pancoasts syndrome

• Focal calcifications and cystic changes

• can extend through an intervertebral foramen, resulting in dumbbell-shaped tumors, and neurologic symptoms of spinal cord compression

• Gross Histology

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

• Microscopic histology

• • composed of spindle cells with elongated nuclei, forming interlacing bundles with focal nuclear palisading

• • nuclear atypia, and stromal sclerosis in older lesions

• • Mitotic figures are rare.

• • Immunohistochemical studies reveal a strongly positive reaction with S-100 protein.

13. Mediastinal Benign Schwannoma 14. Anatomic Distribution of Masses

A mass may extend beyond these boundaries as it grows in size

In adults, anterior compartment masses are more likely to be malignant

15. Age Distribution

Age can help predict etiology of the mass

• infants and children, neurogenic tumors and enterogenous cysts are the most common mediastinal masses

• In adults, neurogenic tumors, thymomas, and thymic cysts are most frequently encountered lesions

• In 20-40 year olds, the likelihood of a mass being malignant is greater secondary to the increased incidence of lymphoma (Hodgkins and non-Hodgkin's) and germ cell tumors

16. Signs and Symptoms

Depend on location of mass

Asymptomatic

Vague symptoms

• aching pain

• cough

Children more likely to be symptomatic

• respiratory difficulty

• recurrent pulmonary infections

17. Signs and Symptoms

Airway compression

• recurrent pulmonary infection

• hemoptysis

Esophageal compression

• dysphagia

Involvement of the spinal column

• paralysis

Phrenic nerve damage

• elevated hemidiaphragm

18. Signs and Symptoms

Recurrent laryngeal nerve involvement

• Hoarseness

Sympathetic ganglion involvement

• Horners Syndrome

• • Ptosis, miosis, anhidrosis

superior vena cava involvement

• Superior vena cava syndrome

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

Horners Syndrome 19. Signs and Symptoms

Can also be associated with systemic diseases

• Thymoma: myasthenia gravis, immune deficiency, red cell aplastic anemia

• Goiter: thyroxicosis

• Thymic carcinoid: Cushings syndrome

• Parathyroid: hyperparathyroidism

20. Evaluation: Imaging

2 view PA/Lat Chest X-ray

• comparisons with old x-rays important

Chest CT with contrast

• most important method of evaluation

• Can help determine location, morphology, size, and attenutation coefficient

• Important for directing further therapy

MRI

• when contrast allergy or renal failure present

• when vascular or chest wall involvement is suspected

• neurogenic tumors (especially helpful in detecting intraspinal component

Ultrasound

• Differentiate 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 scanning

• Can localize specific tumors (pheochromocytoma, paragangliomas, neuroblastomas, neurogangliomas by targeting their metabolic pathways

21. Evaluation: Laboratory

Depends on clinic setting, but may include:

• Thyroid function tests

• • If goiter suspected

• Chemistry panel including calcium and phosphate and PTH

• • If parathyroid adenoma suspected

• Fractionated 24-hour urinary metanephrines and catecholamines

• • If paraganglionic tumor suspected

• AFP/beta HCG

• • In all males with anterior mediastinal tumor because of concern for non-seminomatous germ cell tumor