Evaluation of Evaluation of Mediastinal MassMediastinal Mass

Leslie Proctor, M.D.Leslie Proctor, M.D.

November 21, 2008November 21, 2008

Mediastinal AnatomyMediastinal Anatomy

Includes structures Includes structures bound by:bound by: the thoracic inletthe thoracic inlet diaphragmdiaphragm sternumsternum vertebral bodiesvertebral bodies and pleuraand pleura

Has 3 compartmentsHas 3 compartments AnteriorAnterior MiddleMiddle PosteriorPosterior

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.

Mediastinal AnatomyMediastinal AnatomyAnterior Compartment Anterior Compartment

includes:includes:

ThymusThymus Extrapericardial aorta and itsExtrapericardial aorta and its

branchesbranches The great veinsThe great veins Lymphatic tissue.Lymphatic tissue.

Middle Compartment is Middle Compartment is bounded by:bounded by:

The pericardium anteriorlyThe pericardium anteriorly The posterior pericardial The posterior pericardial

reflectionreflection The diaphragmThe diaphragm The thoracic inlet. The thoracic inlet. This compartment includes the This compartment includes the

heart, intrapericardial great heart, intrapericardial great vessels, pericardium, and vessels, pericardium, and trachea. trachea.

• Extends from the posterior pericardial reflection to the posterior border of the vertebral bodies and from the first rib to the diaphragm. • It includes the esophagus, vagus nerves, thoracic duct, sympathetic chain, and azygous venous system

Posterior Compartment:

Anatomic Distribution of Anatomic Distribution of MassesMasses

Anterior MediastinumAnterior Mediastinum

Thymic tumors and cystsThymic tumors and cysts Germ cell tumorsGerm cell tumors LymphomasLymphomas Intrathoracic goiter and Intrathoracic goiter and

thyroid tumorsthyroid tumors Parathyroid adenomasParathyroid adenomas Connective tissue tumorsConnective tissue tumors

- lipomas and liposarcomaslipomas and liposarcomas- lymphangiomaslymphangiomas- hemangiomashemangiomas

ThymomaThymoma

Anatomic Distribution of Anatomic Distribution of MassesMasses

Middle MediastinumMiddle Mediastinum

Thyroid tumor or Thyroid tumor or goitergoiter

Tracheal tumorsTracheal tumors Aortopulmonary Aortopulmonary

paragangliomaparaganglioma paracardial cystsparacardial cysts bronchogenic cystsbronchogenic cysts lymphomalymphoma

LymphadenopathyLymphadenopathy

Retrosternal GoiterRetrosternal Goiter

Anatomic Distribution of Anatomic Distribution of MassesMasses

Posterior MediastinumPosterior Mediastinum

Neurogenic tumorsNeurogenic tumors including Schwannomasincluding Schwannomas

Esophageal tumorsEsophageal tumors Hiatal HerniasHiatal Hernias Neurenteric CystsNeurenteric Cysts And rarelyAnd rarely

extramedullary extramedullary hematopoiesishematopoiesis

pancreatic pseudocystpancreatic pseudocyst achalasiaachalasia

Paraspinal GanglioneuromaParaspinal Ganglioneuroma

About Neurogenic About Neurogenic tumors…tumors…

9 to 39 percent of all mediastinal tumors9 to 39 percent of all mediastinal tumors develop from mediastinal peripheral nerves, sympathetic and parasympathetic ganglia, develop from mediastinal peripheral nerves, sympathetic and parasympathetic ganglia,

and embryonic remnants of the neural tube. and embryonic remnants of the neural tube. most frequent in the posterior compartment of the mediastinummost frequent in the posterior compartment of the mediastinum Can cause neurologic symptoms by compression.Can cause neurologic symptoms by compression. Benign Schwannoma is most commonBenign Schwannoma is most common

often asymptomatic, but can be associated with Horner’s or Pancoast’s syndromeoften asymptomatic, but can be associated with Horner’s or Pancoast’s syndrome Focal calcifications and cystic changes Focal calcifications and cystic changes can extend through an intervertebral foramen, resulting in dumbbell-shaped tumors, can extend through an intervertebral foramen, resulting in dumbbell-shaped tumors,

and neurologic symptoms of spinal cord compressionand neurologic symptoms of spinal cord compression Gross HistologyGross Histology

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

Microscopic histologyMicroscopic histology composed of spindle cells with elongated nuclei, forming interlacing bundles with composed of spindle cells with elongated nuclei, forming interlacing bundles with

focal nuclear palisadingfocal nuclear palisading nuclear atypia, and stromal sclerosis in older lesionsnuclear atypia, and stromal sclerosis in older lesions Mitotic figures are rare. Mitotic figures are rare. Immunohistochemical studies reveal a strongly positive reaction with S-100 Immunohistochemical studies reveal a strongly positive reaction with S-100

protein.protein.

Mediastinal Benign Mediastinal Benign SchwannomaSchwannoma

Anatomic Distribution of Anatomic Distribution of MassesMasses

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

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

Age DistributionAge Distribution

Age can help predict etiology of the Age can help predict etiology of the massmass infants and children, neurogenic tumors and infants and children, neurogenic tumors and

enterogenous cysts are the most common enterogenous cysts are the most common mediastinal massesmediastinal masses

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

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

Signs and SymptomsSigns and Symptoms Depend on location of Depend on location of

massmass AsymptomaticAsymptomatic Vague symptoms Vague symptoms

aching painaching pain coughcough

Children more likely to Children more likely to be symptomaticbe symptomatic respiratory difficultyrespiratory difficulty recurrent recurrent

pulmonary pulmonary infectionsinfections

Signs and SymptomsSigns and Symptoms Airway compressionAirway compression

recurrent pulmonary recurrent pulmonary infectioninfection

hemoptysis hemoptysis Esophageal Esophageal

compression compression dysphagiadysphagia

Involvement of the Involvement of the spinal columnspinal column paralysis paralysis

Phrenic nerve damagePhrenic nerve damage elevated hemidiaphragm elevated hemidiaphragm

Signs and SymptomsSigns and Symptoms Recurrent laryngeal Recurrent laryngeal

nerve involvementnerve involvement HoarsenessHoarseness

Sympathetic ganglion Sympathetic ganglion involvementinvolvement Horner’s SyndromeHorner’s Syndrome

Ptosis, miosis, anhidrosisPtosis, miosis, anhidrosis

superior vena cava superior vena cava involvementinvolvement Superior vena cava Superior vena cava

syndromesyndrome facial neck, and UE facial neck, and UE

swelling, dyspnea, chest swelling, dyspnea, chest and UE pain, mental and UE pain, mental status changesstatus changes

Horner’s Syndrome

Signs and SymptomsSigns and Symptoms

Can also be associated with systemic Can also be associated with systemic diseasesdiseases Thymoma: myasthenia gravis, immune Thymoma: myasthenia gravis, immune

deficiency, red cell aplastic anemiadeficiency, red cell aplastic anemia Goiter: thyroxicosisGoiter: thyroxicosis Thymic carcinoid: Cushing’s syndromeThymic carcinoid: Cushing’s syndrome Parathyroid: hyperparathyroidismParathyroid: hyperparathyroidism

Evaluation: ImagingEvaluation: Imaging 2 view PA/Lat Chest X-ray2 view PA/Lat Chest X-ray

comparisons with old x-rays importantcomparisons with old x-rays important Chest CT with contrastChest CT with contrast

most important method of evaluationmost important method of evaluation Can help determine location, morphology, size, and attenutation coefficientCan help determine location, morphology, size, and attenutation coefficient Important for directing further therapyImportant for directing further therapy

MRIMRI when contrast allergy or renal failure presentwhen contrast allergy or renal failure present when vascular or chest wall involvement is suspectedwhen vascular or chest wall involvement is suspected neurogenic tumors (especially helpful in detecting intraspinal componentneurogenic tumors (especially helpful in detecting intraspinal component

UltrasoundUltrasound Differentiate cystic from solid masses and relate to surrounding structuresDifferentiate cystic from solid masses and relate to surrounding structures When mass is close to heart or pericardiumWhen mass is close to heart or pericardium Transesophageal or transbronchial useful to evaluate lymph nodes, sometimes for Transesophageal or transbronchial useful to evaluate lymph nodes, sometimes for

biopsybiopsy Radio nucleotide scanningRadio nucleotide scanning

With radioactive iodine when thyroid tumor suspectedWith radioactive iodine when thyroid tumor suspected PET scanningPET scanning

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

Evaluation: LaboratoryEvaluation: Laboratory Depends on clinic setting, but may include:Depends on clinic setting, but may include:

Thyroid function testsThyroid function tests If goiter suspectedIf goiter suspected

Chemistry panel including calcium and phosphate and Chemistry panel including calcium and phosphate and PTHPTH

If parathyroid adenoma suspectedIf parathyroid adenoma suspected Fractionated 24-hour urinary metanephrines and Fractionated 24-hour urinary metanephrines and

catecholaminescatecholamines If paraganglionic tumor suspectedIf paraganglionic tumor suspected

AFP/beta HCGAFP/beta HCG In all males with anterior mediastinal tumor because In all males with anterior mediastinal tumor because

of concern for non-seminomatous germ cell tumorof concern for non-seminomatous germ cell tumor

ManagementManagement Tailored to specific or likely Tailored to specific or likely

diagnosisdiagnosis Must decide whether to excise, Must decide whether to excise,

biopsy, or aspirate lesionbiopsy, or aspirate lesion Excision should be done Excision should be done

with teratomas, thymomas, with teratomas, thymomas, and isolated masses likely and isolated masses likely to be benign (VATS, median to be benign (VATS, median sternotomy, thoracotomy)sternotomy, thoracotomy)

Needle aspiration of cystic Needle aspiration of cystic lesionslesions

Diagnostic biopsy is Diagnostic biopsy is procedure of choice when procedure of choice when suspect lymphoma, germ suspect lymphoma, germ cell tumor, or unresectable cell tumor, or unresectable invasive malignancyinvasive malignancy

ReferencesReferences Kallab, Andre MD. Kallab, Andre MD. Superior Vena Cava SyndromeSuperior Vena Cava Syndrome. Emedicine. August 10 2005. . Emedicine. August 10 2005.

http://www.emedicine.com/MED/topic2208.htmhttp://www.emedicine.com/MED/topic2208.htm

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

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

Strolls, DC, Rosado-de-Christenson, ML, Jett, JR. Strolls, DC, Rosado-de-Christenson, ML, Jett, JR. Primary mediastinal tumors. Part I: Tumors of the Primary mediastinal tumors. Part I: Tumors of the anterior mediastinumanterior mediastinum. Chest 1997; 112:511. . Chest 1997; 112:511.

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

Medscape.com (multiple images)Medscape.com (multiple images)

Devouassoux-Shisheboran, Mojgan MD and Travis, William D MD. Pathology of Mediastnal Devouassoux-Shisheboran, Mojgan MD and Travis, William D MD. Pathology of Mediastnal Tumors. Uptodate. September 9Tumors. Uptodate. September 9thth, 2008., 2008.