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Mesothelioma
 How
is mesothelioma diagnosed?
If
there is a reason to suspect you may have
a mesothelioma, the doctor will use one or
more methods to find out if the disease is
really present.
Medical
history and physical
examination:
A
complete medical history (interview) is
taken to check for risk factors and
symptoms. This will include questions to
determine if you have been exposed to
asbestos.
A
physical exam will provide information
about signs of mesothelioma and other
health problems. Patients with pleural
mesotheliomas (mesotheliomas of the chest)
often have pleural effusion (fluid in
their chest cavity) caused by the cancer.
Ascites (fluid in the abdominal cavity) in
cases of peritoneal mesothelioma, and
pericardial effusion (fluid in the
pericardium) in cases of pericardial
mesothelioma can also be detected during a
physical exam.
Imaging
tests:
A
chest x-ray may show irregular thickening
of the pleura, pleural calcifications
(mineral deposits), lowering of the lung
fissures (spaces between the lobes of the
lungs), and fluid in the pleural space.
These findings suggest asbestos exposure
leading to the development of a
mesothelioma.
Imaging
studies such as x-rays, computed
tomography (CT) scans, and magnetic
resonance imaging (MRI) scans will help
determine the location, size, and extent
of the cancer. The CT scan uses a rotating
x-ray beam to create a series of pictures
of the body from many angles. A computer
combines these pictures to produce
detailed cross-sectional images of a
selected part of the body. To highlight
details on the CT scan, you may be asked
for permission to have a harmless dye
injected into a vein. MRI uses magnetic
fields instead of x-rays to create images
of selected areas of the body. As with the
CT scan, a computer generates a detailed
cross-sectional image.
Tests
of fluid and tissue samples:
In
patients with a pleural effusion, a sample
of this fluid can be removed by inserting
a needle into the chest cavity. A similar
technique can be used to obtain abdominal
fluid and pericardial fluid. The fluid is
then tested to show its chemical make up
and viewed under a microscope to determine
whether cancer cells are present.
A
tissue sample of a pleural or pericardial
tumor can be obtained using a relatively
new technique called thoracoscopy. A
thoracoscope (telescope-like instrument
connected to a video camera) is inserted
through a small incision into the chest.
The doctor can see the tumor through the
thoracoscope, and can use special forceps
to take a tissue biopsy. Similarly,
laparoscopy can be used to see and obtain
a biopsy of a peritoneal tumor. In this
procedure, a flexible tube attached to a
video camera is inserted into the
abdominal cavity through small incisions
on the front of the abdomen. Fluid can
also be collected during thoracoscopy or
laparoscopy.
Surgery,
either a thoracotomy (which opens the
chest cavity) or a laparotomy (which opens
the abdominal cavity), allows the surgeon
to remove a larger sample of tumor or,
sometimes, to remove the entire
tumor.
For
patients who might have pleural
mesothelioma, the doctor may also do a
bronchoscopy. In this procedure a flexible
lighted tube is inserted through the
mouth, down the trachea, and into the
bronchi to see if there are other masses
in the airway. Small samples of
abnormal-appearing tissue can be removed
for testing.
The
patient may also have a mediastinoscopy. A
lighted tube is inserted under the sternum
(chest bone) at the level of the neck and
moved down into the chest. Mediastinoscopy
allows the surgeon to view the lymph nodes
in this area and remove samples to check
for cancer. Lymph nodes are bean-sized
collections of immune system cells that
help the body fight infections and
cancers. Cancers arising in the lung often
spread to lymph nodes, but mesotheliomas
rarely do this. Tests of lymph nodes can
give the doctor information on whether a
cancer is still localized or if it has
started to spread, and can help
distinguish lung cancer from
mesothelioma.
It
is often hard to diagnose mesothelioma by
looking at the cells from the fluid around
the lungs, abdomen or heart. It is even
hard to diagnose mesothelioma with tissue
from biopsies. Under the microscope,
mesothelioma can look like several other
types of cancer. For example, pleural
mesothelioma may resemble some types of
lung cancer and peritoneal mesothelioma
may resemble some cancers of the ovaries.
For this reason, special laboratory tests
are often done to help distinguish
mesothelioma from some other cancers.
These tests often use special techniques
to recognize certain markers (types of
chemicals) known to be contained in
mesotheliomas. Different markers are
present in cancer of the lung or ovary.
The electron microscope can sometimes be
helpful in diagnosing mesothelioma. This
microscope can magnify samples more than
100 times greater than the light
microscope which is generally used in
cancer diagnosis. This stronger microscope
makes it possible to see small parts of
the cancer cells that distinguish
mesothelioma from other types of
cancer.
The
diagnosis of mesothelioma presents
problems primarily initially in the
distinction between mesothelioma and other
forms of cancer such as adenocarcinoma or
benign, noncancerous pleural inflammation.
The best diagnostic tools at the moment
remain the open pleural biopsy performed
during thoracoscopy. This procedure also
allows for direct visualization of the
inside of the chest, and information of
involvment of other organs and extension
of disease. Other procedures with lower
yields are CT guided pleural biopsy, or
blind pleural biopsy. In addition to the
gross appearance of the tumor,
pathologists often rely on a panel of
histochemical and immunohistochemical
stains to diagnose or exclude
meosothelioma. Currently markers linked to
prognosis of mesothelioma are under study,
but have not been validated for the
general use.
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you have any questions regarding your
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