Small Cell Mesothelioma

Image of Small Cell Mesothelioma

Small cell mesothelioma is a rare cell type of epithelial mesothelioma that gets its name from the tumor's cell shape, which is small in comparison to other mesothelioma cell types. This type of mesothelioma is diagnosed when more than 50 percent of the tumor's cells are made up of small cells. The distinct cell shape and pattern is what differentiates it from other forms of epithelioid mesothelioma. The diagnosis and treatment process for this rare cell subtype remains similar to other forms of mesothelioma cancer.

Small cell mesothelioma is usually found in younger, male patients. It is more common among patients with peritoneal mesothelioma, which is the second most common form of the cancer and accounts for 10 to 20 percent of all mesothelioma cases. However, some cases show instances when small cell has been found in the pleura. Causes of the small cell subtype are consistent with the causes of all forms of mesothelioma, and symptoms are also similar when compared to other types of mesothelioma.

Because of its cellular pattern and shape, small cell mesothelioma can often resemble small cell lung cancer. Pathologically, it can be difficult to distinguish these two diseases apart. Through the methods of differential diagnosis, scientists can rule out small cell lung cancer when testing confirms small cell mesothelioma is present. Once this rare mesothelioma subtype is diagnosed, doctors can provide a more accurate prognosis and treatment options to the patient.

Causes

As with other forms of mesothelioma, asbestos exposure is the primary cause of small cell mesothelioma. Prolonged and repeated exposure to the toxic substance increases an individual's chances of developing the rare disease. Occupational asbestos exposure is more likely to cause this cancer than secondary or environmental exposure.

Take for example a case study of an actual small cell patient. A 53-year old woman, who was a non-smoker, presented with thoracic pain and was diagnosed with small cell mesothelioma. She showed a history of asbestos exposure, which was classified as the cause of her cancer. Testing revealed that her tumor contain epithelioid cells, small cells and cells that resembled small cell lung cancer; but the small cells made up enough majority to diagnose her tumor as small cell mesothelioma.

Researchers are not conclusive as to what causes the cells in small cell mesothelioma to form the way they do. The definitive fact that is understood is that asbestos exposure can cause all forms of mesothelioma.

Symptoms

The location of the small cell mesothelioma tumor will determine the symptoms that are present. The tumor's small cell type does not influence the symptoms. Although small cell can occur in the pleura, it will more often be found in peritoneal mesothelioma. Symptoms related to peritoneal mesothelioma are thus more likely to be present in small cell mesothelioma cases.

Diagnosis

Patients often wonder whether the diagnostic process for small cell mesothelioma differs from the traditional mesothelioma diagnostic process. The simple answer is: No. All the diagnostic tools and steps are the same for small cell mesothelioma cases.

With most cases of mesothelioma, the diagnostic process involves multiple steps, beginning with understanding the patient's current health status. In order for a doctor to perform a proper diagnosis, they must first understand the patient's medical history and extent of prior asbestos exposure, in addition to performing a physical examination. Then imaging scans such as X-rays or a CT Scan will be used to locate the cancer. The next and crucial step is a biopsy, where a doctor gets a tissue or fluid sample of the tumor for testing.

Doctors will then test the biopsy to verify what type of cancer is present. Small cell mesothelioma cells contain specific biomarkers, which are diagnostic indicators to pathologists. These biomarkers help pathologists to discern small cell mesothelioma from similar diseases. Thorough pathological testing of the biopsy sample is crucial because small cell mesothelioma can be misdiagnosed as small cell carcinoma of the lung, better known as small cell lung cancer.

Treatment and Prognosis

Treatment options for patients diagnosed with small cell mesothelioma are the same as any other type of mesothelioma. As most mesothelioma diagnoses come with a grim prognosis, patients still may have the option of exploring varying treatment options, depending on the stage of the cancer.

Surgery is an option that may be curative if caught early enough, but may also be palliative, which aims to relieve symptoms rather than cure the cancer. Chemotherapy is another treatment method that may prove to be effective, if found in early stages. Chemotherapy drugs like cisplatin are commonly used in parallel with pemetrexed and may give the patient a longer life span. Another treatment option that may be available includes radiation therapy, which involves the application of radiation to the location of the cancer in hope of shrinking the tumor. Additionally, clinical trials offer a variety of experimental treatments that are not available to the general public.

According to experts, the vast majority of small cell mesothelioma patients will not live beyond two years. Since small cell mesothelioma is considered a subtype of epithelioid mesothelioma, the prognosis is in-line with that of epithelioid, which has a median survival rate around one year after diagnosis. Epithelioid mesothelioma does have the best prognosis out of all the mesothelioma cell types, with most patients living several months longer than other mesothelioma patients.