mediastinal tumors investigations

TUMOURS OF MEDIASTINUM

DIAGNOSTIC WORK UP

DR ARNAB BOSEDept. of RadiotherapyNRS Medical College, Kolkata

INTRODUCTION

There are several types of mediastinal tumors, with their causes linked to where they form in the mediastinum.

Anterior mediastinum Germ cell - The majority of germ cell neoplasms are

benign and are found in both males and females. Lymphoma – Malignant tumors that include both

Hodgkin’s disease and non Hodgkin’s lymphoma. Thymoma and thymic cyst - The majority of

thymomas are benign lesions. However, about 30% of these may be more aggressive and become invasive.

Thyroid mass mediastinal – Usually a benign growth, such as a goiter, these can occasionally be cancerous.

INTRODUCTION

Middle mediastinum

Bronchogenic cyst Lymphadenopathy mediastinal – An

enlargement of the lymph nodes. Pericardial cyst Thyroid mass mediastinal – Usually a benign

growth, such as a goiter, these can occasionally be cancerous.

Tracheal tumors – These include tracheal neoplasms and benign tumors .

Vascular abnormalities including aortic aneurysm and aortic dissection

INTRODUCTION

Posterior mediastinum

Extramedullary haematopoiesis Lymphadenopathy mediastinal – An

enlargement of the lymph nodes. Neuroenteric cyst mediastinal Neurogenic neoplasm mediastinal – The most

common cause of posterior mediastinal tumors, these are classified as nerve sheath neoplasms, ganglion cell neoplasms, and paraganglionic cell neoplasms. Approximately 70% of neurogenic neoplasms are benign.

SIGNS & SYMPTOMS

Almost 40% of people who have mediastinal tumors experience no symptoms.

Most of the growths are often discovered on a chest x-ray that is performed for another reason.

When symptoms are present they are often a result of the compression of surrounding structures, such as the spinal cord, heart or the pericardium .

SIGNS & SYMPTOMS

Cough Shortness of breath Chest pain Fever Chills Night sweats Haemoptysis Hoarseness Unexplained weight loss Lymphadenopathy Wheezing Stridor

CHEST X-RAY

o Chest radiography is the first study that would

be performed in an individual with symptoms referable to the thorax.

o The PA view allows for determination of bilaterality and superior or inferior location, while the lateral chest radiograph determines the specific compartment.

o This information, combined with the age, and associated clinical findings, aids the physician in the proper choice of subsequent diagnostic studies.

CHEST X-RAY

Whenever one sees a mass on a chest x-ray that is possibly located within the mediastinum, the goal is to determine the following:

Is it a mediastinal mass? Is it in the anterior, middle or posterior

mediastinum? Is it possible to characterize the lesion by

determining whether it has any fatty, fluid or vascular components?

CHEST X-RAY

It is important to remember the following:

Most masses are: Thymomas Neurogenic Tumors Benign Cysts Lymphadenopathy Lymphomas

In children the most common are: Neurogenic tumors Germ cell tumors Foregut cysts

In adults the most common are: Lymphomas Lymphadenopathy Thymomas Thyroid masses

CHEST X-RAY

The following characteristics indicate that a lesion originates within the mediastinum:

Unlike lung lesions, a mediastinal mass will not contain air bronchograms.

The margins with the lung will be obtuse. Mediastinal lines (azygo esophageal recess,

anterior and posterior junction lines) will be disrupted.

There can be associated spinal, costal or sternal abnormalities.

LUNG MASS MEDIASTINAL MASS

LUNG MASS MEDIASTINAL MASS

CHEST X-RAY

The mediastinum can be divided into anterior, middle and posterior compartments.

On the lateral radiograph the anterior and middle compartments can be separated by drawing an imaginary line anterior to the trachea and posteriorly to the inferior vena cava.

The middle and posterior compartments can be separated by an imaginary line passing 1 cm posteriorly to the anterior border of the vertebral bodies.

C T SCAN

CT has become a routine part of the diagnostic evaluation of mediastinal tumors, cysts, and other masses.

This test can greatly assist in determining the

exact location of the mediastinal tumor and its relationship to adjacent structures.

It also is useful in differentiating masses that originate in the mediastinum from those that encroach upon the mediastinum from the lung or other structures.

C T SCAN

It also detects pulmonary and mediastinal metastasis and differentiates from mediastinal fatty mass.

The CT scan is very useful in differentiating

tissue densities. This assists greatly in distinguishing structures that are cystic or vascular from those that are solid.

CT scanning can reveal evidence of local invasion of adjacent structures by a mass or the presence of intra thoracic metastases.

MAGNETIC RESONANCE IMAGING

MRI is useful in both the initial diagnosis of a mediastinal mass and in follow-up evaluation after treatment.

It provides superior vascular images and can help better delineate the relationship of an identified mediastinal mass to nearby intrathoracic vascular structures.

MRI can help differentiate between a possible mediastinal mass and a vascular abnormality such as an aortic aneurysm.


MRI offers direct multi planar imaging. It can be used when iodinated contrast is

contraindicated. MRI provides increased detail in the sub carinal

and aorto pulmonary window areas and in the inferior aspects of the mediastinum at the level of the diaphragm.


MRI is more useful than the CT scan in the

evaluation of invasion or extension of tumors, especially tumors closely associated with the heart.

MRI is superior to the CT scan for the evaluation of masses located at the thoracic inlet or at the thoraco abdominal level.

CT is superior in detecting pulmonary metastasis, spacial relationship to other mediastinal structures, and bony destruction.


MRI is especially superior to CT for the evaluation of neurogenic tumors of the mediastinum and can eliminate the need for additional studies such as myelography.

It can be augmented with magnetic resonance angiography if more extensive evaluation of associated vascular structures is needed, eliminating the need for separate conventional angiography studies.

MRI is used increasingly for evaluation of residual or recurrent disease after treatment of lymphoma.

LABORATORY INVESTIGATIONS

Hemoglobin, hematocrit, and white blood cell count Red blood cell aplasia is found in approximately 5% of patients with thymoma and manifests as a normochromic-normocytic anemia. Although rare, neutropenia can be found in association with thymomas.

Gamma globulin levels Hypogammaglobulinemia is associated with some cases of thymoma


Beta human chorionic gonadotropin

Elevated levels of bhCG virtually always are found in association with non seminomatous germ cell tumors.

Seminomas generally do not produce elevated levels of this substance. Less than 10% of patients with seminoma have an elevated bhCG level, and the measured level is usually much lower than that found with non seminomatous tumors.


Alpha-fetoprotein AFP almost always is elevated in individuals

with non seminomatous germ cell tumors. Elevation of the AFP level is not found in

individuals with pure seminoma.

Lactate Dehydrogenase


Thyroid-stimulating hormone and thyroid function studies Functioning thyroid adenomas can develop in ectopic mediastinal thyroid tissue and can cause thyroid stimulating hormone suppression and associated elevation of serum triiodothyronine levels.

Serum and 24-hour urinary catecholamine levels should be measured in all infants and children who present with a posterior mediastinal or paravertebral mass. These levels are frequently elevated in patients with neuroblastoma and ganglioneuroblastoma.

Adrenocorticotropic hormone (ACTH) levels The thorax should always be investigated for the source of ectopic ACTH production. A neuroendocrine or carcinoid tumor of the thorax should be excluded. These tumors occur in the mediastinum, particularly in the thymus gland, and in the lung.

Antidiuretic hormone levels: These may be elevated with some neuroendocrine tumors of the thymus.


RADIONUCLIDE SCANNING Nuclear imaging can be used selectively in the

workup of mediastinal masses when specific tumors are suggested.

Gallium Ga 67 is used commonly in the evaluation of mediastinal lymphoma, both for initial evaluation and for post therapy follow-up.

The iodine I 131 or iodine I 123 scans are very helpful in distinguishing thyroid tissue from other masses. They are often used in identifying an anterior mediastinal mass located at the level of the thoracic inlet as the sub sternal extension of a cervical thyroid goiter.

RADIONUCLIDE SCANNING

Scanning with technetium Tc 99m sestamibi may be useful in the identification of mediastinal parathyroid tissue.

The octreotide scan, using indium In 111–labeled pentetreotide, is useful for localizing various neuroendocrine neoplasms, including carcinoid tumors, pheochromocytomas, and para gangliomas.

ECHOCARDIOGRAPHY & ULTRASONOGRAPHY

Ultrasonographic methods have been used to help differentiate solid from cystic mediastinal masses and to assist in determining the connection between a mass and adjacent structures.

The findings from these studies are more useful in the evaluation of masses associated with the heart and in vascular abnormalities.

In general, given the accuracy and detail provided by CT scan images, MRI, and selected radionuclide scan findings, ultrasound techniques are generally not used as a primary tool in the evaluation of mediastinal tumors and cysts.

POSITRON EMISSION TOMOGRAPHY

PET scan findings have been studied extensively for the evaluation of a number of neoplasms such as lung, colorectal, breast, lymphoma, and melanoma. The usefulness of this study in the evaluation of mediastinal tumors is being evaluated.

PET has proven a useful test in for helping identify some pheochromocytomas.

Some results of using PET scan for thymomas suggest that a high 18-fluorodeoxyglucose (FDG) uptake on PET scan reflects the invasiveness of malignant nature of thymic tumors and can be used to differentiate these from benign thymomas.

ARTERIOGRAPHY

Conventional Angiography findings have been used to differentiate mediastinal masses from vascular abnormalities and to exhibit the relationship between known masses and adjacent vascular structures.

MRI and Magnetic Resonance Angiography have replaced conventional angiography in most cases.

TRANSTHORACIC NEEDLE BIOPSY

CT-guided fine-needle aspiration (FNA) and core needle biopsy techniques increasingly are used with success at several centers.

Differentiation of thymomas, lymphomas, and germ cell tumors can be made in a number of cases when tissue obtained from a core needle biopsy is subjected to special histologic staining methods, including immunohistochemical techniques.

In some cases, lymphoma subtypes can be identified as well.

TRANSTHORACIC NEEDLE BIOPSY

Considerable expertise in tissue processing and analysis is

necessary for diagnostic accuracy, which is reported to be 85-95%.

FNA has been used occasionally to aid in the diagnosis of primary bronchogenic cysts. However, most authorities do not recommend aspiration of a cyst because a sample of the cyst wall, required for diagnosis, is not obtained by this method.

FNA has been described for neurogenic tumors, although because surgical resection is the treatment for these lesions after adequate workup, needle biopsy may be deemed an unnecessary step.

MEDIASTINOSCOPY

Cervical Mediastinoscopy is a commonly used surgical diagnostic procedure for evaluation of the retro vascular pre tracheal area of the mediastinum.

This procedure is used most commonly for staging of bronchogenic carcinoma and for evaluation of hilar and para tracheal lymphadenopathy, but it can be modified into what has been termed a Sub-sternal Extended Mediastinoscopy to evaluate the pre vascular area of the mediastinum.

MEDIASTINOSCOPY

Thymic masses and any tumors found in the anterior mediastinum (eg, germ cell tumors), as well as lymph nodes of the aorto pulmonary window, are accessible for obtaining a biopsy using this approach.

Tumors located in the posterior mediastinum, where most neurogenic tumors are found, are not approachable using this method.

Some lesions of neurogenic origin, when located high in the mediastinum in the region of the thoracic inlet, may be approached and resected through a cervical approach.

MEDIASTINOTOMY

Anterior Mediastinotomy - this para sternal approach to the mediastinum has been used most commonly in situations in which standard cervical mediastinoscopy was believed or found to be inadequate.

It classically is performed in the upper left para sternal area for access to the aorto pulmonary window and areas of the anterior mediastinum inferior to the aortic arch.

Anterior Mediastinotomy is being replaced in many centers either by Extended Cervical Mediastinoscopy or by Video-Assisted Thoracic Surgical (VATS) techniques.

MEDIASTINOTOMY

Posterior Mediastinotomy - this is a rarely used procedure for biopsy of some of the posteriorly situated lymph nodes or a mass in the paravertebral sulcus.

Performed most commonly on the right side in a paravertebral location immediately lateral to the paravertebral muscles.

It is rarely used for mediastinal tumors and

cysts because these are more appropriately managed by either standard Thoracotomy or VATS techniques.

VIDEO ASSISTED THORACOSCOPY

VATS techniques have been used successfully for biopsy of various mediastinal masses and are used commonly for the sampling of perihilar lymph nodes.

VATS is one of the commonly used methods for evaluation of mediastinal lymphoma.

STERNOTOMY & THORACOTOMY

In spite of the numerous minimally invasive options available for histologic diagnosis of mediastinal tumors and cysts, open surgical access is needed at times.

In some cases, standard Sternotomy or Thoracotomy may be the safest method available to obtain an adequate tissue diagnosis.

Some surgeons perform a Partial Upper Sternotomy, in which only the superior portion of a typical Sternotomy is performed. It is a less invasive technique that is safe and effective for accessing the anterosuperior mediastinum.

THYMOMA WORK UP

Upto 50% patients – asymptomatic with anterior mediastinal mass on CXR

Others – symptoms due to local compression or as paraneoplastic syndrome ( eg. – Myasthenia Gravis )

CXR (PA) -rounded/oval lesion with smooth or lobulated border near the junction of ht. & gt. vsls.

CXR (Lat)-opacity at anterior cardiac window CT Scan-helps in evaluating extent of mass MRI-investigating vascular invasion Indium labelled octreotide scan CT Guided FNAC Surgical Biopsy

EXTRA GONADAL G C T WORK UP

More than 90% of patients have symptoms due to local compression or invasion to adjacent structures (dyspnoea, cough, chest pain, SVCO,etc)

CXR - mass in the antero superior mediastinum

CT Scan Thorax, Abdomen, Pelvis – evaluation of the mass, screening for metastasis & lymphadenopathy

USG Scrotum – detecting occult primary Tumour Markers – AFP, Beta HCG, LDH CT Guided FNAC with cytologic staining for

tumour markers

LYMPHOMA WORK UP

CBC count with differential and platelets. Electrolyte panel and liver function tests. Elevation in the serum lactic dehydrogenase

(LDH) or β-2 microglobulin level value is an adverse prognostic feature.

The markers alpha-fetoprotein and β-human chorionic gonadotropin (βHCG) are often highly elevated in patients with mediastinal germ cell tumors, constituting an important differential diagnosis .

LYMPHOMA WORK UP

CXR (PA, lateral)- A mass larger than one third of the diameter of the thorax is considered bulky and indicates a poor prognosis.

CT scans (chest, abdomen, pelvis)- Extension to the pleura, pericardium, and even the chest wall is common. Invasion of the liver, kidneys, and peripheral lymph nodes is more common at the time of recurrence.

Findings on a gallium scan are almost always strongly positive.

PET scans represents a convenient, and probably more sensitive, alternative to a gallium scan.

LYMPHOMA WORK UP

Adequate diagnostic biopsy is needed and may require surgery.

Ancillary studies, which include immunohistochemistry, immunophenotyping (flow cytometry), and gene rearrangement studies, are often necessary to establish the diagnosis.

Bone marrow aspirate and biopsy are necessary for staging.

LYMPHOMA WORK UP

Biopsy of a lymph node or of the mediastinal mass with the use of mediastinoscopy or parasternotomy is necessary

Fine-needle aspiration is usually not diagnostic in this disorder due to lack of morphologic architecture .

Other tests should be performed if clinically indicated (eg, thoracentesis for pleural effusion, lumbar puncture for for neurologic symptoms).

THANK YOU

Health & Medicine

mediastinal tumors investigations