CT-Scan of the Chest
The patient’s presentation is classical for malignant mesothelioma. Malignant mesothelioma is associated with asbestos exposure – occupations with known asbestos exposure include ceramics, as well as shipbuilding, construction, paper mill, auto parts, railroad, and insulation.
A CT-Scan will most likely show pleural effusion and ideally pleural thickening and nodularity. Chest X-ray would also be a common choice, which would show pleural effusion, but would most likely only show advanced disease with a peripheral mass. Pleural fluid analysis could show malignant mesothelioma cells, but is usually non-diagnostic. Technically the CT-Scan is also non-diagnostic, but is the best choice given the patient’s presentation and the emergency department setting. With the patient’s presentation and suggestive CT-Scan, thoracoscopically guided biopsy of the pleura is 98% diagnostic for malignant mesothelioma.
YES
Technically there are two types of mesothelioma:
1. Localized (benign or malignant)
2. Diffuse (highly malignant)
Localized mesothelioma often presents with: pleuritic pain, joint pain and swelling, and dyspnea. Diffuse mesothelioma often presents with chest pain (not necessarily pleuritic), malaise, weight loss, and cough. Pleural effusion is the hallmark sign presenting in greater than 75% of diffuse cases, but on 10% to 15% of the time in local disease. Benign disease presents as “broccoli” or “cauliflower” pedunculated masses on the visceral pleura, as opposed to the “sheet like” growth of malignant disease. Overall malignant mesothelioma occurs in the pleura 90% of the time. Pleural malignant mesothelioma is associated with asbestos exposure in 77% of cases.
Malignant Mesothelioma
First off – What are mesothelial cells?
Mesothelial cells make up the lining of your body’s cavities: pleura, peritoneum. pericardium, testis, etc.
Why does asbestos cause this?
If you just said to yourself, I have no clue? Don’t worry you’re not alone. Researchers are still unsure how this happens as well. In general, remember that malignant mesothelioma is a type of cancer and the generally accepted theory on the cause of cancers is one of multifactorial instigators. Despite an elusive cause, some information is known concerning asbestos and malignant mesothelioma. Direct contact of asbestos fibers with body tissues (most commonly lung tissue from inhalation) causes a local inflammation reaction. Inflammation factors over time may block the natural function of tumor suppressor genes and allow overgrowth of mesothelial cells. Current theory points to a tumor suppressor gene on chromosome 9 called p-16.
The Butchart System is used most often and is based on the extent of the primary tumor mass. The stages are as follows:
• Stage I: Tumor is limited to the right or left pleura; it may also involve the ipsilateral diaphragm.
• Stage II: Tumor involves the chest wall, esophagus, heart, or pleural surfaces bilaterally; adenopathy in the chest is present.
• Stage III: Tumor has penetrated through the diaphragm to the abdomen; there is adenopathy beyond the chest.
• Stage IV: Metastatic disease is present in other organs throughout the body.
The TNM System (Stage I – V) is based on T (tumor), N (nodes) and M (metastases). The stages quantify levels of tumor involvement, presence of lymph nodes and presence of metastases.
The Brigham System (Stage I – IV) stages mesotheliomas based on the resectability of the tumor and status of lymph node involvement.
• Imaging: Plain films, CT and MRI are used to detect thickening, nodules and masses on the pleural surface of the lungs, peritoneum and pericardium. Ascites and lymphadenopathy can also be appreciated on imaging.
• Cytology: Examination of pleural, pericardial and abdominal fluid for the presence of malignancy is unreliable in diagnosis as 85% of patients have negative or inconclusive studies.
• Needle Biopsy: Obtaining tissue from the chest cavity via needle biopsy is thought to be approximately 25 – 60% accurate in the diagnosis of mesothelioma. If this procedure is performed, the biopsy tract is radiated to prevent seeding of the tumor.
• Open Biopsy: Obtaining a larger amount of tissue through open biopsy under general anesthesia is the most accurate diagnostic tool for mesothelioma. The tissue is obtained for pathological evaluation of potential malignant cells. Local radiation is also used to prevent seeding of the tumor.
Exposure to asbestos in certain occupations places patients at risk for mesothelioma. Workers in the field of insulation, fireproofing, plumbing, pipe fitting, plastering, cement production, shipyard construction, boiler making and the automotive brake and clutch industry. Environmental hazards such as joint compound, transite siding, gunnite, roof, floor and ceiling tiles, wall plasters and insulation all pose a threat to patients.
Other rare causes are irradiation of the chest wall, intrapleural thorium dioxide and inhalation of fibrous silicate.
There may be a viral connection to mesothelioma. The Simian Virus 40 (SV40) may be a cofactor in the development of mesothelioma.
Additionally, others living with asbestos workers are at risk of developing this disease. It is thought that exposed workers bring home fibers of asbestos in their clothing and hair which in turn expose their families. Mandatory showering before leaving the workplace is felt to decrease this risk.
The early symptoms of mesothelioma can be somewhat vague and non-specific. Pleural mesothelioma patients usually present with what appears to be a viral pneumonia. This can include cough, shortness of breath or chest pain. Some of the less common symptoms are weight loss, fever and night sweats. A delay in diagnosis often occurs due to the generalized nature of the complaints and the fact that many other illnesses present in this manner.
Peritoneal mesothelioma patients generally present with abdominal pain and swelling, weight loss, peripheral edema, bowel obstruction and ascites.
As the fluid accumulation progresses, symptoms become more severe. There is increased shortness of breath, chest and/or abdominal pain, profound fatigue and a dry cough. Mesothelioma of the pericardium may result in pericardial effusion which can lead to cardiac tamponade which is a cardiac emergency. Long term survival of mesothelioma patients is generally unexpected.
Mesothelioma is an asbestos related cancer of the lining of various organs in the body. In mesothelioma, malignant cells develop in the mesothelium which is the protective lining that covers the internal organs. The mesothelium develops from the mesoderm in the embryo which lines the embryonic body cavity. The mesoderm ultimately forms the layer of cells that become the visceral lining of the organs or the parietal sac around a cavity. The most common sites are the lining of the lung (pleura), the abdomen (peritoneum) or the heart (pericardium). There are three subtypes of mesothelioma which correspond to the types of cells seen in each site. These subtypes are epithelioid, sarcomatoid and biphasic or mixed. Each subtype has a specific microscopic appearance to allow this determination. The subtypes differ in their response to treatment and the aggressiveness of their disease.