Mesothelioma

INTRODUCTION
Mesothelioma is a very rare type of cancer in which cancer cells invade the mesothelium, the protective covering that covers most of the internal organs.
The mesothelium is composed of two layers of cells: one layer is in contact with the body, while the latter forms a pocket around. The mesothelium produces a lubricating fluid that allows both layers one above the other movements allowing covering bodies (eg, the lungs) slide . Depending on your location, the mesothelium given a particular name: the one surrounding the lungs is called pleura, which surrounds the heart called the pericardium, which surrounds the testicles is called the tunica vaginalis testis and surrounding the uterus is called uterine tunica. Most of the abdominal organs are covered by peritoneum


Pleural mesothelioma
Pleural mesothelioma is the most common, with an incidence 9 times higher than the peritoneal mesothelioma. It is more common in men than in women, with the age of onset of symptoms between 50-70 years with a latency period of 20-40 years. In 80% of cases the cause is exposure to asbestos dust. Other possible causes of mesothelioma are radiation therapy and polio vaccines contaminated with simian virus SV40. Pleural mesothelioma is approximately 3% of malignant neoplasms of the pleura, and when the diagnosis is made for the course is rapid and invariably fatal, usually during the next two years.
The most common clinical presentation is diffuse chest pain, which can occasionally be pleuritic or radiating to the shoulder accompanied by pleural effusions. Dyspnea, cough, weakness, malaise and fatigue usually appear in later stages of the disease. In 89% of cases, abnormal electrocardiogram being the most frequent abnormalities sinus tachycardia (42%), ventricular arrhythmias or headphones (17%) and a branch block bundle (30%)
The most common radiographic finding is an irregular opacity in the lung periphery, associated with ipsilateral pleural effusion with evidence of loss of volume contraction committed hemithorax and no mediastinal shift to the opposite side, despite significant pleural effusions ( * ) The diagnosis should be suspected when pleural thickening surrounding the lung trapping and fixing the mediastinum is.
From the histological point of view, the mesoepitelioma is classified into 3 types:
Epithelioid covering 50% of cases and generally better prognosis and life expectancy;
sarcomatoid that occurs between 7 to 20% of cases;
mixed or biphasic occurs in 20 to 35% of the cases,
From the standpoint of the pathologist, mesothelioma metastatic adenocarcinoma differs in the following aspects:
PropertyMesotheliomaAdenocarcinomaGlycogen in cytoplasmabundantlittle bitStaining mucicarminenegativepositiveHyaluronic acid production20% is producednoCytokeratin 5/6, calretinin and thrombomodulinpositivenegativeCEA *negativepositive
* CEA: CEA
In 1976 Butchard proposed the following classification of the stages of mesoepitelioma:
• Stage I: tumor confined within the "capsule" of the parietal pleura (affecting only the ipsilateral lung, pericardial pleura and diaphragm)
• Stage II: tumor invading the chest, mediastinal lymph nodes or wall
• Stage III: penetrating the diaphragm affecting the peritoneum corresponding to the opposite pleura
• Stage IV: with blood dissemination and distant metastases
Other classifications frequently used in the clinic are the Sugarbaker, 1993 ( * )
DIAGNOSIS ( * )
The diagnosis of pleural mesothelioma is often difficult because the symptoms are similar to many other conditions. Diagnosis begins with a review of the medical history of the patient, followed by a complete physical examination, including a chest radiograph and pulmonary function studies. Computed tomography and resonance can be useful to determine the extent and location of the lesion.
To confirm the diagnosis biopsy can be done by thoracoscopy (requires * ) or, if this is not possible by conventional surgery. Once the doagnóstico confirmed, determine what stage is the disease with the purpose of making the best treatment
TREATMENT
Surgery.
3 types of surgery are used to treat mesoepitelioma. Diagnostic surgery to obtain a sample for biopsy is performed thoracoscopic ( *), or laparoscopic or open pleural mediatinoscopia surgery. Second, palliative surgery including partial pleurectomy with pleurodesis, thoracoscopy with pleurodesis and more rarely, pleuroperitoneal shunt. The third is curative surgery involving extrapleural pneumonectomy in order to remove most of the tumor. In most centers, this surgery is followed by adjuvant therapy. Not all patients are candidates for this procedure, which otherwise has a 6% mortality
Chemotherapy
Although there have been several chemotherapy regimens, none has proved to be curative. The two most useful (in the sense of reducing the tumor mass and improve symptoms) are pemetrexed + cisplatin + cistaplatino and gemcitabine. In both cases, we recommend adding dexamethasone and folic acid and vitamin B12
Radiotherapy
Radiotherapy has been used for many years with disappointing results due to the diffuse nature of the tumor as it may cause radiation pneumonitis. Just found some effectiveness when applied locally on the scar area after surgery remains preventing disseminated tumor cells
Other treatments under investigation include immunotherapy, gene therapy, photodynamic therapy and some antiangiogenic agents
REFERENCES
Yesner, R. Atlas of Lung Cancer. 1998. Lippincott. 291páginas
De Vita, V. Principles and Practice of Oncology (2005) Lippincott. 3120 pages + CD-ROM
F. Clifton Mountain, MD; Libshitz I. Herman, MD; and Kay E. Hermes. LUNG CANCER . A Handbook for Staging, Imaging, and Lymph Node Classification
Villalba Caloca J, R Martinez Crown. Frequency of malignant mesothelioma. Clinical review. Journal of the National Institute of Respiratory Diseases , (2003), Vol. 16 Issue 3, p150-158 (Ref.1)
Robinson BWS, Musk AW, Lake RA. Malignant mesothelioma. Lancet, (2005), Vol. 366 Issue 9483, p397-409 (ref 2)
British Thoracic Society Standards of Care Committee. Statement on malignant mesothelioma United Kingdom Thorax 2001; 56: 250-265 (ref.3)
Sterman DH, Albelda SM. Advances in the diagnosis, evaluation, and management of malignant pleural mesothelioma. Respirology,(2005) Vol 10 Issue 3, p266-82.;
Monograph revised on October 13, 2005. Drafting Team BSI