Mesothelium

What Is the Mesothelium?

The mesothelium is a dynamic cellular membrane that gently covers and protects our organs and tissues. It helps our body respond to injuries, infections and diseases. The mesothelium also moves fluids across cavities and manages inflammation. Doctors identify the types of mesothelium membranes by the organs they cover.

Different Types of Mesothelium

• The pleural mesothelium covers the lungs and chest wall
• The peritoneal (parietal) mesothelium covers the abdominal organs and abdominal wall
• The pericardial mesothelium covers the heart
• The tunica vaginalis covers the testes

Inhaling asbestos fibers can trap them in the mesothelium, irritating and harming the soft tissue over time. Exposure to asbestos can lead to mesothelioma and other diseases. Some studies show that the lymphatic system may carry asbestos fibers into the mesothelium.

Mesothelium Structure and Function

The mesothelium has two forms: Visceral and parietal. The visceral mesothelium covers the lung and other internal organs. The parietal mesothelium covers the surrounding cavity walls such as the chest cavity.

While the mesothelium’s role is protection, its tissue is slow to renew. Less than 1% of the cells undergo cell division at any one time.

Functions of the Mesothelium

• Transporting fluids and cells
• Inflammation and tissue repair
• Protection against invading microorganisms
• Presenting antigens (immune proteins) to lymphocytes (immune cells)
• Blood clotting to heal wounds
• Tumor cell adhesion to prevent cancerous spreading

Serosal fluid, which contains sugars, enzymes and blood proteins, bathes the mesothelium.

Recent advances in immunotherapy and checkpoint molecules have increased the number of studies examining the interaction between immune cells and mesothelial cells. These studies could be crucial in treating malignant mesothelioma and other mesothelium diseases.

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Diseases of the Mesothelium

Cancer can start in the mesothelium due to inflammation and scarring. If this damage does not heal, the mesothelium may form fibrous adhesions. These changes in mesothelial cells can cause malignant mesothelioma and other cancers.

Effusions occur when fluid builds up between the layers of the mesothelium. A pleural effusion accumulates around the lungs. While a peritoneal effusion accumulates around the abdomen.

Effusions can signal a problem. But they are just symptoms of mesothelial diseases, such as pleural and peritoneal diseases, not the main issue.

Pleural Diseases

Benign and cancerous diseases of the pleura can develop because of asbestos exposure.

• Pleuritis is inflammation of the pleura.
• Pleural plaques are fibrous scar tissue on the pleura that may become calcified.
• Pleural thickening is extensive scarring that thickens and restricts the pleura.
• Atelectasis is a contraction of pleural scar tissue that folds the pleura into the lung. This causes the lungs to underinflate.
• Pleural mesothelioma is cancer of the pleura.

Pleural mesothelioma is the most serious pleural disease. Its latency period is between 20 and 60 years, so seeing a doctor early is important if you develop any of the other pleural diseases that could signal something much worse.

Peritoneal Diseases

Benign and cancerous diseases can also develop in the peritoneum.

• Peritonitis is inflammation of the peritoneum.
• Peritoneal mesothelioma is a cancer of the peritoneum.
• Primary peritoneal serous carcinoma is another cancer of the peritoneum.

Asbestos exposure is the main cause of peritoneal mesothelioma. Peritonitis is when the peritoneum becomes inflamed. It is often caused by bacterial or fungal infections.

A cancer called primary peritoneal serous carcinoma can develop in the peritoneum. A 2022 study published in the Scholars Journal of Medical Case Reports compared it to advanced-stage serous ovarian carcinoma, highlighting its importance in understanding these conditions.

Pericardial Diseases

Several benign conditions and cancers can develop in the pericardium.

• Pericarditis is inflammation of the pericardium.
• Cardiac tamponade is compression of the heart by fluid accumulation.
• Pericardial constriction is scarring and a loss of elasticity of the pericardium.
• Pericardial mesothelioma is a cancer of the pericardium.
• Several other cancers can develop in the pericardium, including sarcomas, lymphoma and primitive neuroectodermal tumors.

Pericardial mesothelioma is the most serious of the pericardial diseases, but it’s also rare. About 1% of people diagnosed with mesothelioma have the pericardial type. Its treatment options are limited because of the sensitive location of the tumors.

Tunica Vaginalis Diseases

Benign and cancerous diseases can develop in the tunica vaginalis.

• Hydrocele is an abnormal amount of fluid between the layers of the tunica vaginalis.
• Scrotal calculi are calcified deposits that form between the layers of the tunica vaginalis.
• Fibrous pseudotumors are benign lesions of the tunica vaginalis.
• Testicular mesothelioma is cancer of the tunica vaginalis.
• Several other cancers can develop in the tunica vaginalis, including mesenchymal tumors, lymphomas and serous borderline tumors.
• A few benign tumors can develop as well, including adenomatoid tumors, scrotal tunica cysts, lipoma and leiomyoma.

The mesothelium plays an important role in protecting our organs and responding to issues like inflammation, injury and disease.

If you were exposed to asbestos and have unusual symptoms in your lungs, abdomen, heart, or testes, please see your doctor. It’s always best to stay proactive about your health.

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