胸膜炎（きょうまくえん）とは、肺の外部を覆う胸膜（壁側胸膜＝肋膜・肺胸膜）に炎症が起こる疾患である。かつては肋膜炎（ろくまくえん）とも呼ばれていた。胸膜炎はそれ自体で発症することは少なく、ほとんどは癌・結核・肺炎などの後に発症することが多い。

This can result in a sharp chest pain while breathing.^[1] Occasionally the pain may be a constant dull ache.^[5] Other symptoms may include shortness of breath, cough, fever, or weight loss, depending on the underlying cause.^[5] Pleurisy can be caused by a variety of conditions, including viral or bacterial infections, autoimmune disorders, and pulmonary embolism.

The most common cause is a viral infection.^[2] Other causes include bacterial infection, pneumonia, pulmonary embolism, autoimmune disorders, lung cancer, following heart surgery, pancreatitis and asbestosis.^[2] Occasionally the cause remains unknown.^[2] The underlying mechanism involves the rubbing together of the pleurae instead of smooth gliding.^[1] Other conditions that can produce similar symptoms include pericarditis, heart attack, cholecystitis, pulmonary embolism, and pneumothorax.^[3] Diagnostic testing may include a chest X-ray, electrocardiogram (ECG), and blood tests

• 胸の痛み（胸水が溜まることによる）
• 呼吸困難（胸水が溜まることによる）
• 発熱
• 咳・痰　など

• 癌による胸膜炎（がん性胸膜炎）

  肺癌をはじめとするほかの部位にできたがんの転移などによるもの

• 結核菌による胸膜炎

  肺結核をはじめとして結核菌によるもの

• その他の疾患による胸膜炎

  肺炎や肺の化膿など肺に細菌が感染したことに伴うもの

  慢性関節リウマチなどに伴うもの

  心臓疾患や肺疾患に伴うもの　など

• Pleural effusion

  In some cases of pleurisy, excess fluid builds up in the pleural space. This is called a pleural effusion. The buildup of excess fluid, will more often than not force the two layers of the pleura apart so they do not rub against each other when breathing. This can relieve the pain of pleurisy. A large amount of fluid can result in collapse of the lung. This can make it difficult to breathe.

  In some cases of pleural effusion, the excess fluid becomes infected and turns into an abscess. This is called an empyema.

  Pleural effusion involving fibrinous exudates in the fluid may be called fibrinous pleurisy, which sometimes occurs as a later stage of pleurisy.

  A person can develop a pleural effusion in the absence of pleurisy. For example, pneumonia, heart failure, cancer, or a pulmonary embolism can lead to a pleural effusion.

  Pneumothorax

  Air or gas also can build up in the pleural space. This is called a pneumothorax. It can result from acute lung injury or a lung disease like emphysema. Lung procedures, like surgery, drainage of fluid with a needle, examination of the lung from the inside with a light and a camera, or mechanical ventilation, also can cause a pneumothorax.

  The most common symptom is sudden pain in one side of the lung and shortness of breath. A pneumothorax also can put pressure on the lung and cause it to collapse.

  If the pneumothorax is small, it may go away on its own. If large, a chest tube is placed through the skin and chest wall into the pleural space to remove the air.

  Hemothorax

  Blood also can collect in the pleural space. This is called hemothorax. The most common cause is injury to the chest from blunt force or surgery on the heart or chest. Hemothorax also can occur in people with lung or pleural cancer.

  Hemothorax can put pressure on the lung and force it to collapse. It also can cause shock, a state of hypoperfusion in which an insufficient amount of blood is able to reach the organs.