This is an uncommon lesion, usually affecting young patients (mean age, 30 years), with a male to female ratio of 2:1. The middle ear is involved, although it may extend to the external auditory canal if there is tympanic membrane perforation.

Symptoms are usually relieved with radiation therapy within one month of treatment. However, even with treatment, 99% of patients die within two and a half years. This relates to the cancerous causes of SVC that are 90% of the cases. The average age of onset of disease is 54 years of age.

Malignant germ cell tumors of the mediastinum are uncommon, representing only 3 to 10% of tumors originating in the mediastinum. They are much less common than germ cell tumors arising in the testes, and account for only 1 to 5% of all germ cell neoplasms.

Syndromes associated with mediastinal germ cell tumors include Hematologic Neoplasia and Klinefelter's syndrome.

An otic polyp (also called aural polyp) is a benign proliferation of chronic inflammatory cells associated with granulation tissue, in response to a longstanding inflammatory process of the middle ear.

The pleural space can be invaded by fluid, air, and particles from different parts of the body which fairly complicates the diagnosis. Viral infection (coxsackie B virus, HRSV, CMV, adenovirus, EBV, parainfluenza, influenza) is the most common cause of pleurisy. However, many other different conditions can cause pleuritic chest pain:

- Aortic dissections

- Autoimmune disorders such as systemic lupus erythematosus (or drug-induced lupus erythematosus), Autoimmune hepatitis (AIH), rheumatoid arthritis and Behçet's disease.

- Bacterial infections associated with pneumonia and tuberculosis

- Chest injuries (blunt or penetrating)

- Familial Mediterranean fever, an inherited condition that often causes fever and swelling in the abdomen or the lungs

- Fungal or parasitic infections

- Heart surgery, especially coronary-artery bypass grafting

- Cardiac problems (ischemia, pericarditis)

- Inflammatory bowel disease

- Lung cancer and lymphoma

- Other lung diseases like cystic fibrosis, sarcoidosis, asbestosis, lymphangioleiomyomatosis, and mesothelioma

- Pneumothorax

- Pulmonary embolisms, which are blood clots that enter the lungs

When the space between the pleurae starts to fill with fluid, as in pleural effusion, the chest pain can be eased but a shortness of breath can result, since the lungs need room to expand during breathing. Some cases of pleuritic chest pain are idiopathic, which means that the exact cause cannot be determined.

When a pleural effusion has been determined to be exudative, additional evaluation is needed to determine its cause, and amylase, glucose, pH and cell counts should be measured.

- Red blood cell counts are elevated in cases of bloody effusions (for example after heart surgery or hemothorax from incomplete evacuation of blood).

- Amylase levels are elevated in cases of esophageal rupture, pancreatic pleural effusion, or cancer.

- Glucose is decreased with cancer, bacterial infections, or rheumatoid pleuritis.

- pH is low in empyema (<7.2) and may be low in cancer.

- If cancer is suspected, the pleural fluid is sent for cytology. If cytology is negative, and cancer is still suspected, either a thoracoscopy, or needle biopsy of the pleura may be performed.

- Gram staining and culture should also be done.

- If tuberculosis is possible, examination for "Mycobacterium tuberculosis" (either a Ziehl–Neelsen or Kinyoun stain, and mycobacterial cultures) should be done. A polymerase chain reaction for tuberculous DNA may be done, or adenosine deaminase or interferon gamma levels may also be checked.

The most common causes of exudative pleural effusions are bacterial pneumonia, cancer (with lung cancer, breast cancer, and lymphoma causing approximately 75% of all malignant pleural effusions), viral infection, and pulmonary embolism.

Another common cause is after heart surgery, when incompletely drained blood can lead to an inflammatory response that causes exudative pleural fluid.

Conditions associated with exudative pleural effusions:

- Parapneumonic effusion due to pneumonia

- Malignancy (either lung cancer or metastases to the pleura from elsewhere)

- Infection (empyema due to bacterial pneumonia)

- Trauma

- Pulmonary infarction

- Pulmonary embolism

- Autoimmune disorders

- Pancreatitis

- Ruptured esophagus (Boerhaave's syndrome)

- Rheumatoid pleurisy

- Drug-induced lupus

The Ewing family of tumors is a group of cancers that includes Ewing tumor of bone (ETB or Ewing sarcoma of bone), extraosseous Ewing tumors (EOE tumors), primitive neuroectodermal tumors (PNET or peripheral neuroepithelioma), and Askin tumors (PNET of the chest wall). These tumors all come from the same type of stem cell. Also called EFTs.

Approximately 90% of cases are associated with a cancerous tumor that is compressing the superior vena cava, such as bronchogenic carcinoma including small cell and non-small cell lung carcinoma, Burkitt's lymphoma, lymphoblastic lymphomas, pre-T-cell lineage acute lymphoblastic leukemia (rare), and other acute leukemias. Syphilis and tuberculosis have also been known to cause superior vena cava syndrome. SVCS can be caused by invasion or compression by a pathological process or by thrombosis in the vein itself, although this latter is less common (approximately 35% due to the use of intravascular devices).

The most common causes of transudative pleural effusions in the United States are heart failure and cirrhosis. Nephrotic syndrome, leading to the loss of large amounts of albumin in urine and resultant low albumin levels in the blood and reduced colloid osmotic pressure, is another less common cause of pleural effusion. Pulmonary emboli were once thought to cause transudative effusions, but have been recently shown to be exudative.

The mechanism for the exudative pleural effusion in pulmonary thromboembolism is probably related to increased permeability of the capillaries in the lung, which results from the release of cytokines or inflammatory mediators (e.g. vascular endothelial growth factor) from the platelet-rich blood clots. The excessive interstitial lung fluid traverses the visceral pleura and accumulates in the pleural space.

Conditions associated with transudative pleural effusions include:

- Congestive heart failure

- Liver cirrhosis

- Severe hypoalbuminemia

- Nephrotic syndrome

- Acute atelectasis

- Myxedema

- Peritoneal dialysis

- Meigs' syndrome

- Obstructive uropathy

- End-stage kidney disease

The goal of treatment of malignant pleural effusions is relief of breathlessness. Occasionally, treatment of the underlying cancer can cause resolution of the effusion. This may be the case with types of cancer that respond well to chemotherapy, such as small cell carcinoma or lymphoma. Simple aspiration of pleural fluid can relieve breathlessness rapidly but fluid and symptoms will usually recur within a couple of weeks. For this reason, more permanent treatments are usually used to prevent fluid recurrence. Standard treatment involves chest tube insertion and pleurodesis. However, this treatment requires an inpatient stay of approximately 2–7 days, can be painful and has a significant failure rate. This has led to the development of tunneled pleural catheters (e.g., Pleurx Catheters), which allow outpatient treatment of effusions.

Most cases of SPB progress to multiple myeloma within 2–4 years of diagnosis, but the overall median survival for SPB is 7–12 years. 30–50% of extramedullary plasmacytoma cases progress to multiple myeloma with a median time of 1.5–2.5 years. 15–45% of SPB and 50–65% of extramedullary plasmacytoma are disease free after 10 years.

Some investigators suggest that this distribution arises as a consequence of abnormal migration of germ cells during embryogenesis. Others hypothesize a widespread distribution of germ cells to multiple sites during normal embryogenesis, with these cells conveying genetic information or providing regulatory functions at somatic sites.

The mediastinum (from Medieval Latin "mediastinus", "midway") is the central compartment of the thoracic cavity surrounded by loose connective tissue, as an undelineated region that contains a group of structures within the thorax. The mediastinum contains the heart and its vessels, the esophagus, trachea, phrenic and cardiac nerves, the thoracic duct, thymus and lymph nodes of the central chest.

Plasmacytomas are a rare form of cancer. SPB is the most common form of the disease and accounts for 3-5% of all plasma cell malignancies. The median age at diagnosis for all plasmacytomas is 55. Both SPB and extramedullary plasmacytoma are more prevalent in males; with a 2:1 male to female ratio for SPB and a 3:1 ratio for extramedullary plasmacytoma.

Fibrothorax is diffuse fibrosis of the pleural space surrounding the lungs. It can have several causes including hemothorax, pleural effusion and tuberculosis. It may also be induced by exposure to certain substances, as with asbestos-induced diffuse pleural fibrosis. Idiopathic fibrothorax may also occur.

In fibrothorax, scar tissue is formed around the visceral pleura following inflammation due to pleural effusion or other pathology. The scar tissue lies in a sheet between the pleura, then fuses with the parietal pleura and the chest wall. Over time, generally the course of years, the fibrotic scar tissue slowly tightens, which results in the contraction of the entire hemithorax, and leaves the ribs immobilized. Within the chest, the lung is compressed and unable to expand, making it vulnerable to collapse. At the microscopic level, the scar tissue is composed of collagen fibers deposited in a basket weave pattern. The treatment for fibrothorax is decortication, the surgical removal of the fibrous layer of scar tissue. However, since many of the diseases and conditions resulting in fibrothorax are treatable, prevention remains the preferred method of managing fibrothorax.

Pleurisy and other disorders of the pleurae can be serious, depending on what caused them. Generally, pleurisy treatment has an excellent prognosis, but if left untreated it can cause severe complications. For example, a resulting pulmonary heart disease cor pulmonale, which manifests itself with an inflammation of the arms and legs, can lead to heart failure. If the conditions that caused the pleurisy or other pleural disorders were adequately diagnosed and treated early, one can expect a full recovery. Help of a pulmonologist (respiratory physician in the U.K. and Australia) may be enlisted to address the underlying cause and chart post-illness rehabilitation.

Compared to other breeds of dog, Scottish terriers have a much increased risk of developing transitional cell carcinoma.

Malignant pleural effusion is a condition in which cancer causes an abnormal amount of fluid to collect between the thin layers of tissue (pleura) lining the outside of the lung and the wall of the chest cavity. Lung cancer and breast cancer account for about 50-65% of malignant pleural effusions. Other common causes include pleural mesothelioma and lymphoma.

The condition is rare but serious, and appears in all mammals. It results from leakage of lymph fluid from the thoracic duct (or one of its tributaries). This can result from direct laceration (e.g., from surgery) or from nontraumatic causes. The most common nontraumatic cause is malignancy, especially lymphoma. Less common is left-heart failure, infections, and developmental abnormalities such as Down syndrome and Noonan syndrome.

Costochondritis is a common condition and is responsible for 30% of emergency room chest pain related visits. One-fifth of visits to the primary care physician are for musculoskeletal chest pain; of this 20% of primary care office visits, 13% is due to costochondritis. Costochondritis cases are most often seen in people older than age 40 and occurs more often in women.

Bladder cancer in cats and dogs usually is transitional cell carcinoma, which arises from the epithelial cells that line the bladder. Less often, cancer of the urinary bladder is squamous cell carcinoma, adenocarcinoma, or rhabdomyosarcoma.

"Widened mediastinum/mediastinal widening" is where the mediastinum has a width greater than 6 cm on an upright PA chest X-ray or 8 cm on supine AP chest film.

A widened mediastinum can be indicative of several pathologies:

- aortic aneurysm

- aortic dissection

- aortic unfolding

- aortic rupture

- hilar lymphadenopathy

- anthrax inhalation - a widened mediastinum was found in 7 of the first 10 victims infected by anthrax ("Bacillus anthracis") in 2001.

- esophageal rupture - presents usually with pneumomediastinum and pleural effusion. It is diagnosed with water-soluble swallowed contrast.

- mediastinal mass

- mediastinitis

- cardiac tamponade

- pericardial effusion

- thoracic vertebrae fractures in trauma patients.

Since the mechanism behind chylothorax is not well understood, treatment options are limited. Drainage of the fluid out of the pleural space is essential to obviate damage to organs, especially the inhibition of lung function by the counter pressure of the chyle. Another treatment option is pleuroperitoneal shunting (creating a communication channel between pleural space and peritoneal cavity). By this surgical technique loss of essential triglycerides that escape the thoracic duct can be prevented. Omitting fat (in particular FFA) from the diet is essential. Either surgical or chemical pleurodesis are options: the leaking of lymphatic fluids is stopped by irritating the lungs and chest wall, resulting in a sterile inflammation. This causes the lung and the chest wall to be fused together which prevents the leaking of lymphatic fluids into the pleural space. The medication octreotide has been shown to be beneficial and in some cases will stop the chylothorax after a few weeks.

In animals, the most effective form of treatment until recently has been surgical ligation of the thoracic duct combined with partial pericardectomy. There is at least one case report (in a cat) of clinical response to treatment with rutin.

Lung hernia (Sibson hernia) is a protrusion of lung outside of thoracic wall. In 20% patients with lung hernia, the incidence is congenital. In 80% of the cases, the hernia is noted after chest trauma, thoracic surgery or certain pulmonary diseases. Congenital hernia occurs because of the weakness of the suprapleural membrane or neck muscles. In pulmonary diseases such as asthma, frequent coughing can lead to high intra thoracic pressure, causing the lung to herniate out. Lung hernia may occur near the neck (cervical), between the ribs (intercostal), near the vertebrae (paravertebral) or near the sternum (parasternal).

A hemothorax is a type of pleural effusion in which blood accumulates in the pleural cavity. This excess fluid can interfere with normal breathing by limiting the expansion of the lungs. The term is from "" + "thorax".