What is Mesothelioma? Symptoms, Causes & Diagnosis

Understanding Mesothelioma: An Overview

Mesothelioma is a rare and aggressive form of cancer that develops in the thin layer of tissue that covers most of your internal organs (mesothelium). The disease is divided into different types based on which part of the mesothelium is affected. Pleural mesothelioma, which affects the tissue that surrounds the lungs, is the most common form, accounting for about 75% of all cases.

This devastating disease is almost exclusively caused by exposure to asbestos, a naturally occurring mineral that was widely used in construction, manufacturing, and various industries throughout the 20th century. When asbestos fibers are inhaled or ingested, they can become lodged in the mesothelium, causing inflammation and genetic damage to cells that may eventually lead to mesothelioma.

Types of Mesothelioma

Mesothelioma is classified based on the location in the body where it develops. Each type has distinct characteristics, symptoms, and treatment approaches.

Pleural Mesothelioma

Pleural mesothelioma develops in the lining of the lungs (pleura) and accounts for approximately 75% of all mesothelioma cases. This type occurs when asbestos fibers are inhaled and become lodged in the pleura, causing inflammation and scarring that can eventually lead to cancer.

Peritoneal Mesothelioma

Peritoneal mesothelioma develops in the lining of the abdomen (peritoneum) and represents about 20% of mesothelioma cases. This form occurs when asbestos fibers are ingested or inhaled and then travel to the abdominal cavity.

Pericardial Mesothelioma

Pericardial mesothelioma develops in the lining around the heart (pericardium) and is extremely rare, accounting for about 1% of cases. The mechanism by which asbestos fibers reach the pericardium is not fully understood.

Testicular Mesothelioma

Testicular mesothelioma develops in the tunica vaginalis, the membrane surrounding the testes. This is the rarest form of mesothelioma, representing less than 1% of cases.

Causes and Risk Factors of Mesothelioma

The primary cause of mesothelioma is exposure to asbestos, a group of naturally occurring minerals that were widely used in various industries for their heat resistance and durability.

Asbestos Exposure

Asbestos exposure is the leading cause of mesothelioma. When asbestos-containing materials are disturbed, microscopic fibers are released into the air and can be inhaled or swallowed. These sharp, durable fibers then become lodged in the mesothelium, where they cause inflammation and scarring over time, eventually leading to genetic damage and cancer development.

Occupational Exposure

Many cases of mesothelioma result from occupational exposure to asbestos. Workers in certain industries faced particularly high risks, including:

• Construction workers
• Shipyard workers
• Industrial workers
• Power plant workers
• Automotive mechanics (especially brake repair)
• Plumbers and pipefitters
• Electricians

Secondary Exposure

Secondary exposure occurs when asbestos fibers are brought home on the clothing, skin, or hair of workers, potentially exposing family members to the dangerous fibers. This was particularly common before safety regulations were implemented.

Environmental Exposure

In some cases, people living near natural asbestos deposits or asbestos mines may be exposed to fibers in the environment. Additionally, natural disasters like hurricanes or tornadoes can disturb asbestos-containing materials in older buildings, releasing fibers into the air.

Symptoms of Mesothelioma

Mesothelioma symptoms typically don't appear until 20-50 years after initial asbestos exposure, making early detection challenging. The symptoms vary depending on the type of mesothelioma.

Pleural Mesothelioma Symptoms

• Persistent dry or painful cough
• Shortness of breath
• Chest pain under the rib cage
• Painful breathing
• Unusual lumps of tissue under the skin on the chest
• Unexplained weight loss
• Fatigue

Peritoneal Mesothelioma Symptoms

• Abdominal pain and swelling
• Nausea and vomiting
• Unexplained weight loss
• Loss of appetite
• Bowel obstruction
• Fluid buildup in the abdomen (ascites)

Other Types of Mesothelioma Symptoms

Pericardial mesothelioma may cause heart palpitations, chest pain, and difficulty breathing. Testicular mesothelioma typically presents as a mass or swelling on a testicle.

Diagnosing Mesothelioma

Diagnosing mesothelioma can be challenging because its symptoms resemble those of many other conditions. A comprehensive diagnostic process typically involves multiple steps.

Medical History and Physical Examination

The diagnostic process begins with a thorough medical history, including questions about asbestos exposure, and a physical examination to check for signs of mesothelioma such as fluid accumulation or unusual lumps.

Imaging Tests

Imaging tests help doctors visualize abnormalities that might indicate mesothelioma:

• Chest X-ray: May show thickening of the pleura or fluid buildup
• CT scan: Provides detailed cross-sectional images of the body
• PET scan: Helps identify cancerous areas by tracking glucose consumption
• MRI: Offers detailed images of soft tissues

Biopsy Procedures

A biopsy, which involves removing a small sample of tissue for laboratory analysis, is the only way to confirm a mesothelioma diagnosis. Different biopsy techniques include:

• Fine-needle aspiration: Using a thin needle to extract fluid or tissue
• Thoracoscopy: Inserting a tiny camera into the chest cavity to guide tissue collection
• Laparoscopy: Similar to thoracoscopy but for abdominal examination
• Open surgery: In some cases, a larger tissue sample may be necessary

Pathology and Staging

Once tissue samples are obtained, pathologists examine them under a microscope to confirm the diagnosis and determine the cell type (epithelioid, sarcomatoid, or biphasic). If mesothelioma is confirmed, further tests will determine the stage of the cancer, which guides treatment decisions.