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Diagnosis
CT scan of a patient with mesothelioma, coronal section (the section
follows the plane the divides the body in a front and a back half). The
mesothelioma is indicated by yellow arrows, the central pleural effusion
(fluid collection) is marked with a yellow star. Red numbers: (1) right
lung, (2) spine, (3) left lung, (4) ribs, (5) descending part of the
aorta, (6) spleen, (7) left kidney, (8) right kidney, (9)
liver.Diagnosing mesothelioma is often difficult, because the symptoms
are similar to those of a number of other conditions. Diagnosis begins
with a review of the patient's medical history. A history of exposure to
asbestos may increase clinical suspicion for mesothelioma. A physical
examination is performed, followed by chest X-ray and often lung
function tests. The X-ray may reveal pleural thickening commonly seen
after asbestos exposure and increases suspicion of mesothelioma. A CT (or
CAT) scan or an MRI is usually performed. If a large amount of fluid is
present, abnormal cells may be detected by cytology if this fluid is
aspirated with a syringe. For pleural fluid this is done by a pleural
tap or chest drain, in ascites with an paracentesis or ascitic drain and
in a pericardial effusion with pericardiocentesis. While absence of
malignant cells on cytology does not completely exclude mesothelioma, it
makes it much more unlikely, especially if an alternative diagnosis can
be made (e.g. tuberculosis, heart failure).
If cytology is positive or a plaque is regarded as suspicious, a biopsy
is needed to confirm a diagnosis of mesothelioma. A doctor removes a
sample of tissue for examination under a microscope by a pathologist. A
biopsy may be done in different ways, depending on where the abnormal
area is located. If the cancer is in the chest, the doctor may perform a
thoracoscopy. In this procedure, the doctor makes a small cut through
the chest wall and puts a thin, lighted tube called a thoracoscope into
the chest between two ribs. Thoracoscopy allows the doctor to look
inside the chest and obtain tissue samples.
If the cancer is in the abdomen, the doctor may perform a laparoscopy.
To obtain tissue for examination, the doctor makes a small opening in
the abdomen and inserts a special instrument into the abdominal cavity.
If these procedures do not yield enough tissue, more extensive
diagnostic surgery may be necessary.
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