- Malignant Mesothelioma.

Malignant Mesothelioma.

Def:-

It is a rare form of cancer that develops from the protective lining that covers many of the body's internal organs,known as the mesothelium.

(CXR demonstrating Mesothelioma of left lower lung)

Sites:-

• Pleura. (is the most common form of the disease, accounting for roughly 70% of cases).
• Peritoneum.
• The pericardium (1).
• The tunica vaginalis.

Causes:- (2)

• It is usually caused by exposure to asbestos.
• other risk factors e.g.contact with a virus called SV40 or exposure to radiation from a chemical called thorium dioxide(Thorotrast).

*Clinical picture:-

Symptoms or signs of mesothelioma may not appear until 20 to 50 years (or more) after exposure to asbestos.

Symptoms of pleural mesothelioma:-

• Shortness of breath.
• cough.
• chest pain.
• Fatigue or anemia.
• Blood in the sputum(hemoptysis).

Symptoms of peritoneal mesothelioma:-

Tumors that affect the abdominal cavity often do not cause symptoms until they are at a late stage and include..

• weight loss and cachexia
• abdominal swelling
• Abdominal pain
• Ascites
• Problems with bowel function

Symptoms of Pericardial mesothelioma:-

• Palpitations
• Irregular heartbeat
• chest pain
• difficulty breathing
• night sweats

Symptoms of Testicular mesothelioma:-
Painful or painless testicular lumps. 

In severe cases of the disease, the following signs and symptoms may be present:

• Thrombophlebitis.
• Disseminated intravascular coagulation.
• Jaundice.
• Low blood sugar level
• Pulmonary emboli
• Severe ascites

N.B:-

• 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 of mesothelioma:-

Diagnosing mesothelioma is often difficult, because the symptoms are similar to those of a number of other conditions.

- Taking history:-

• Patient's medical history.
• A history of exposure to asbestos may increase clinical suspicion for mesothelioma.

Physical examination.

Chest X-ray :- may reveal pleural thickening.
CT (or CAT) scan or MRI .
Lung function tests.

If a large amount of fluid is present, abnormal cells may be detected by cytopathology if this fluid is aspirated with a syringe:-

• For pleural fluid done by thoracentesis or chest tube,
• for ascites, with paracentesis or ascitic drain,
• for 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).


But the diagnosis of malignant mesothelioma by cytology alone is difficult, even with expert pathologists.


Biopsy is needed to confirm a diagnosis of malignant mesothelioma.

Immunohistochemical studies play an important role for the pathologist in differentiating malignant mesothelioma from neoplastic mimics.

*Treatment of mesothelioma:-

Treatment of malignant mesothelioma at earlier stages has a better prognosis.

• Surgery:- Surgery, by itself, has proved disappointing.However, research indicates varied success when used in combination with radiation and chemotherapy (Duke, 2008).
• Radiation:- For patients with localized disease, and who can tolerate a radical surgery, radiation is often given post-operatively as a consolidative treatment. Although mesothelioma is generally resistant to curative treatment with radiotherapy alone, palliative treatment regimens are sometimes used to relieve symptoms arising from tumor growth, such as obstruction of a major blood vessel. Radiation therapy when given alone with curative intent has never been shown to improve survival from mesothelioma. The necessary radiation dose to treat mesothelioma that has not been surgically removed would be very toxic.
• Chemotherapy:- Chemotherapy is the only treatment for mesothelioma that has been proven to improve survival in randomised and controlled trials.
• Immunotherapy:- Treatment regimens involving immunotherapy have yielded variable results. For example, intrapleural inoculation of Bacillus Calmette-Guérin (BCG) in an attempt to boost the immune response, was found to be of no benefit to the patient (while it may benefit patients with bladder cancer).
• Heated Intraoperative Intraperitoneal Chemotherapy:- A procedure known as heated intraoperative intraperitoneal chemotherapy was developed by Paul Sugarbaker at the Washington Cancer Institute.(3) The surgeon removes as much of the tumor as possible followed by the direct administration of a chemotherapy agent, heated to between 40 and 48°C, in the abdomen. The fluid is perfused for 60 to 120 minutes and then drained.
• Multimodality Therapy:- Surgery combined with adjuvant chemotherapy and radiation (trimodality therapy) has produced significant survival extension (3–14 years) among patients with favorable prognostic factors.(4)

*References:-

(1)Ashrafian H, Athanasiou T, Yap J, DeSouza AC. Two-chamber intracardiac mesothelioma. Asian Cardiovasc Thorac Ann. 2005 Jun;13(2):184-6.

(2)"Mesothelioma risks and causes : Cancer Research UK : CancerHelp UK". Cancerhelp.org.uk. 2010-06-23. . Retrieved 2010-08-20.

(3)Sugarbaker PH, Welch LS, Mohamed F, Glehen O (July 2003). "A review of peritoneal mesothelioma at the Washington Cancer Institute". Surg Oncol Clin N Am 12 (3):605–21,xi.doi:10.1016/S1055-3207(03)00045-0.. PMID14567020.
Online manual: Management of Peritoneal Surface Malignancy.

(4)Sugarbaker DJ, Flores RM, Jaklitsch MT et al. (January 1999). "Resection margins, extrapleural nodal status, and cell type determine postoperative long-term survival in trimodality therapy of malignant pleural mesothelioma: results in 183 patients". J Thorac Cardiovasc Surg 117 (1): 54–63; discussion 63–5. doi:10.1016/S0022-5223(99)70469-1. PMID 9869758.