|
Mesothelioma
is a form of cancer that is almost always caused by
previous exposure to asbestos.[1] In this disease, malignant cells
develop in the mesothelium, a protective lining that covers most of
the body's internal organs. Its most common site is the pleura (outer
lining of the lungs and chest cavity), but it may also occur in the
peritoneum (the lining of the abdominal cavity) or the pericardium
(a sac that surrounds the heart).
Most people who develop mesothelioma have worked on jobs where they
inhaled asbestos particles, or have been exposed to asbestos dust
and fibre in other ways, such as by washing the clothes of a family
member who worked with asbestos, or by home renovation using
asbestos cement products. Unlike lung cancer, there is no
association between mesothelioma and smoking
Signs and symptoms
Symptoms of mesothelioma may not appear until 20 to 50 years after
exposure to asbestos. Shortness of breath, cough, and pain in the
chest due to an accumulation of fluid in the pleural space are often
symptoms of pleural mesothelioma.
Symptoms of peritoneal mesothelioma include weight loss and cachexia,
abdominal swelling and pain due to ascites (a buildup of fluid in
the abdominal cavity). Other symptoms of peritoneal mesothelioma may
include bowel obstruction, blood clotting abnormalities, anemia, and
fever. If the cancer has spread beyond the mesothelium to other
parts of the body, symptoms may include pain, trouble swallowing, or
swelling of the neck or face.
These symptoms may be caused by mesothelioma or by other, less
serious conditions.
Mesothelioma that affects the pleura can cause these signs and
symptoms:
* chest wall pain
* pleural effusion, or fluid surrounding the lung
* shortness of breath
* fatigue or anemia
* wheezing, hoarseness, or cough
* blood in the sputum (fluid) coughed up
In severe cases, the person may have many tumor masses. The
individual may develop a pneumothorax, or collapse of the lung. The
disease may metastasize, or spread, to other parts of the body.
Tumors that affect the abdominal cavity often do not cause symptoms
until they are at a late stage. Symptoms include:
* abdominal pain
* ascites, or an abnormal buildup of fluid in the abdomen
* a mass in the abdomen
* problems with bowel function
* weight loss
In severe cases of the disease, the following signs and symptoms may
be present:
* blood clots in the veins, which may cause thrombophlebitis
* disseminated intravascular coagulation, a disorder causing severe
bleeding in many body organs
* jaundice, or yellowing of the eyes and skin
* low blood sugar level
* pleural effusion
* pulmonary emboli, or blood clots in the arteries of the lungs
* severe ascites
A mesothelioma does not usually spread to the bone, brain, or
adrenal glands. Pleural tumors are usually found only on one side of
the lungs.
Diagnosis
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.
|