Identification of pleural fluid biomarkers to distinguish malignant pleural effusions from other causes of exudative effusions would help diagnosis. Biomarkers that have been shown to be raised in malignant pleural effusions compared to benign disease include vascular endothelial growth factor (VEGF), endostatin, matrix metalloproteinases and tumour markers such as carcinoembryonic antigen. Pleural fluid mesothelin has a sensitivity of 71%, greater than that of cytology, and a specificity of 89% for the diagnosis of malignant mesothelioma.

Pleural fluid cytology is positive in 60% of cases. However, in the remaining cases, pleural biopsy is required. Image guided biopsy and thoracoscopy have largely replaced blind biopsy due to their greater sensitivity and safety profile. CT guided biopsy has a sensitivity of 87% compared to Abrams' needle biopsy, which has a sensitivity of 47%.

Following thoracoabdominal trauma, most commonly a penetrating injury, laceration of the diaphragm, and spleen allows ectopic splenic tissue to reach the pleural space of the lung.

Affected persons are usually asymptomatic. However, on rare occasions, thoracic splenosis can present with chest pain and/or hemoptysis.

On radiological studies, thoracic splenic lesions are visualized using CT scans. Visualized lesions can be described as solitary or multiple nodules. The locations of the lesions are mostly in the lower left pleural space and/or splenic bed. Confirmation can be done using scintigraphy with 99mTc tagged heat-damaged red blood cells.

No treatment is required since thoracic splenosis is a benign condition.

Ectopic endometrial tissue reaches the pleural space of the lung or the right hemi-diaphragmatic region and erodes the visceral pleura, causing the formation of a spontaneous pneumothorax. The condition is often cyclical, due to its associations with the beginning of the menstrual cycle.

Affected persons usually present with recurrent spontaneous pneumothorax associated with the onset of the menstrual cycle. Additionally, chest/scapular pain and/or evidence of endometriosis in the abdominopelvic cavity are other manifestations.

On radiological studies, pneumothorax is visualized using conventional chest x-rays and CT scans. In 90% of the cases, the pneumothorax is located on the right side. In some cases, small nodules can be seen in the pleura using CT scans. Confirmation can be done using video assisted thoracoscopic surgery (VATS).

Treatment for the pneumothorax is with chest tube placement. As for the ectopic endometrial tissue, therapy with gonadotropin-releasing–hormone or resection of the lesions can improve symptoms.

Once a pleural effusion is diagnosed, its cause must be determined. Pleural fluid is drawn out of the pleural space in a process called thoracentesis, and it should be done in almost all patients who have pleural fluid that is at least 10 mm in thickness on CT, ultrasonography, or lateral decubitus X-ray and that is new or of uncertain etiology. In general, the only patients who do not require thoracentesis are those who have heart failure with symmetric pleural effusions and no chest pain or fever; in these patients, diuresis can be tried, and thoracentesis is avoided unless effusions persist for more than 3 days. In a thoracentesis, a needle is inserted through the back of the chest wall in the sixth, seventh, or eighth intercostal space on the midaxillary line, into the pleural space. The use of ultrasound to guide the procedure is now standard of care as it increases accuracy and decreases complications. After removal, the fluid may then be evaluated for:

1. Chemical composition including protein, lactate dehydrogenase (LDH), albumin, amylase, pH, and glucose

2. Gram stain and culture to identify possible bacterial infections

3. White and red blood cell counts and differential white blood cell counts

4. Cytopathology to identify cancer cells, but may also identify some infective organisms

5. Other tests as suggested by the clinical situation – lipids, fungal culture, viral culture, tuberculosis cultures, lupus cell prep, specific immunoglobulins

Diagnosis can be hinted by high recurrence rates of lung collapse in a woman of reproductive age with endometriosis. CA-125 is elevated. Video-assisted thoracoscopy is used for confirmation.

A pleural effusion appears as an area of whiteness on a standard posteroanterior chest X-ray. Normally, the space between the visceral pleura and the parietal pleura cannot be seen. A pleural effusion infiltrates the space between these layers. Because the pleural effusion has a density similar to water, it can be seen on radiographs. Since the effusion has greater density than the rest of the lung, it gravitates towards the lower portions of the pleural cavity. The pleural effusion behaves according to basic fluid dynamics, conforming to the shape of pleural space, which is determined by the lung and chest wall. If the pleural space contains both air and fluid, then an air-fluid level that is horizontal will be present, instead of conforming to the lung space. Chest radiographs in the lateral decubitus position (with the patient lying on the side of the pleural effusion) are more sensitive and can detect as little as 50 mL of fluid. At least 300 mL of fluid must be present before upright chest X-rays can detect a pleural effusion (e.g., blunted costophrenic angles).

Chest computed tomography is more accurate for diagnosis and may be obtained to better characterize the presence, size, and characteristics of a pleural effusion. Lung ultrasound, nearly as accurate as CT and more accurate than chest X-ray, is increasingly being used at the point of care to diagnose pleural effusions, with the advantage that it is a safe, dynamic, and repeatable imaging modality. To increase diagnostic accuracy of detection of pleural effusion sonographically, markers such as boomerang and VIP signs can be utilized.

Generally, a biopsy is needed to confirm a diagnosis of malignant mesothelioma. A doctor removes a sample of tissue for examination under a microscope by a pathologist. A biopsy may be done in different ways, depending on where the abnormal area is located. If the cancer is in the chest, the doctor may perform a thoracoscopy. In this procedure, the doctor makes a small cut through the chest wall and puts a thin, lighted tube called a thoracoscope into the chest between two ribs. Thoracoscopy allows the doctor to look inside the chest and obtain tissue samples. Alternatively, the chest surgeon might directly open the chest (thoracotomy). If the cancer is in the abdomen, the doctor may perform a laparoscopy. To obtain tissue for examination, the doctor makes a small incision in the abdomen and inserts a special instrument into the abdominal cavity. If these procedures do not yield enough tissue, an open surgical procedure may be necessary.

Catamenial pneumothorax is the most common form of thoracic endometriosis syndrome, which also includes catamenial hemothorax, catamenial hemoptysis, catamenial hemopneumothorax and endometriosis lung nodules, as well as some exceptional presentations.

Mesothelioma can be prevented in most cases by preventing exposure to asbestos. The US National Institute for Occupational Safety and Health maintains a recommended exposure limit of 0.1 asbestos fiber per cubic centimeter.

A CT scan provides a computer-generated picture of the lungs that can show pockets of fluid. It also may show signs of pneumonia, a lung abscess, or a tumor.

Ultrasonography uses sound waves to create an image. It may show where fluid is located in the chest. It also can show some tumors. Although ultrasound may detect fluid around the lungs, also known as a pleural effusion, sound waves are scattered by air. Therefore, an actual picture of the lungs cannot be obtained with ultrasonography.

The treatment of choice for both benign and malignant SFT is complete "en bloc" surgical resection.

Prognosis in benign SFTs is excellent. About 8% will recur after first resection, with the recurrence usually cured after additional surgery.

The prognosis in malignant SFTs is much more guarded. Approximately 63% of patients will have a recurrence of their tumor, of which more than half will succumb to disease progression within 2 years. Adjuvant chemotherapy and/or radiotherapy in malignant SFT remains controversial.

The purpose of radiologic imaging is to locate the lesion, evaluate for signs of invasion and detect metastasis. Features of GIST vary depending on tumor size and organ of origin. The diameter can range from a few millimeters to more than 30 cm. Larger tumors usually cause symptoms in contrast to those found incidentally which tend to be smaller and have better prognosis. Large tumors tend to exhibit malignant behavior but small GISTs may also demonstrate clinically aggressive behavior.

Plain radiographs are not very helpful in the evaluation of GISTs. If an abnormality is seen, it will be an indirect sign due to the tumor mass effect on adjacent organs. On abdominal x-ray, stomach GISTs may appear as a radiopaque mass altering the shape of the gastric air shadow. Intestinal GISTs may displace loops of bowel and larger tumors may obstruct the bowel and films will show an obstructive pattern. If cavitations are present, plain radiographs will show collections of air within the tumor. Calcification is an unusual feature of GIST but if present can be visible on plain films.

Barium fluoroscopic examinations and CT are commonly used to evaluate the patient with abdominal complaints. Barium swallow images show abnormalities in 80% of GIST cases. However, some GISTs may be located entirely outside the lumen of the bowel and will not be appreciated with a barium swallow. Even in cases when the barium swallow is abnormal, an MRI or CT scan must follow since it is impossible to evaluate abdominal cavities and other abdominal organs with a barium swallow alone. In a CT scan, abnormalities may be seen in 87% of patients and it should be made with both oral and intravenous contrast. Among imaging studies, MRI has the best tissue contrast, which aids in the identification of masses within the GI tract (intramural masses). Intravenous contrast material is needed to evaluate lesion vascularity.

Preferred imaging modalities in the evaluation of GISTs are CT and MRI, and, in selected situations, endoscopic ultrasound. CT advantages include its ability to demonstrate evidence of nearby organ invasion, ascites, and metastases. The ability of MRI to produce images in multiple planes is helpful in determining the bowel as the organ of origin (which is difficult when the tumor is very large), facilitating diagnosis.

The diagnosis of thoracic endometriosis is primarily based on clinical history and examination, augmented with non-invasive studies such as X-ray, CT scan, and magnetic resonance imaging of the chest. Pelvic ultrasound is also useful to determine if the patient has any degree of pelvic or abdominal endometriosis (indicated by the presence of free fluid).

More invasive methods for obtaining a tissue diagnosis of thoracic endometriosis include video thoracoscopy (for pleural or pulmonary biopsy), or bronchoscopy (for pulmonary or bronchial biopsy, or bronchial lavage). A case series has been reported in which clinical diagnosis was made in 50% of patients, the rest being diagnosed either via biopsy (25%) or bronchoalveolar lavage (25%). (25%)

The diagnosis of a mediastinal germ cell tumor should be considered in all young males with a mediastinal mass. In addition to physical examination and routine laboratory studies, initial evaluation should include CT of the chest and abdomen, and determination of serum levels of HCG and alpha-fetoprotein.

The initial investigations for suspected empyema remains chest X-ray, although it cannot differentiate an empyema from uninfected parapneumonic effusion. Ultrasound must be used to confirm the presence of a pleural fluid collection and can be used to estimate the size of the effusion, differentiate between free and loculated pleural fluid and guide thoracocentesis if necessary. Chest CT and MRI do not provide additional information in most cases and should therefore not be performed routinely. On a CT scan, empyema fluid most often has a radiodensity of about 0-20 Hounsfield units (HU), but gets over 30 HU when becoming more thickened with time.

The most often used "golden" criteria for empyema are pleural effusion with macroscopic presence of pus, a positive Gram stain or culture of pleural fluid, or a pleural fluid pH under 7.2 with normal peripheral blood pH. Clinical guidelines for adult patients therefore advocate diagnostic pleural fluid aspiration in patients with pleural effusion in association with sepsis or pneumonic illness. Because pleural effusion in the pediatric population is almost always parapneumonic and the need for chest tube drainage can be made on clinical grounds, British guidelines for the management of pleural infection in children do not recommend diagnostic pleural fluid sampling.

Blood and sputum culture has often already been performed in the setting of community acquired pneumonia needing hospitalization. It should however be noted that the micro-organism responsible for development of empyema is not necessarily the same as the organism causing the pneumonia, especially in adults. As already mentioned before, sensitivity of pleural fluid culture is generally low, often partly due to prior administration of antibiotics. It has been shown that culture yield can be increased from 44% to 69% if pleural fluid is injected into blood culture bottles (aerobic and anaerobic) immediately after aspiration. Furthermore, diagnostic rates can be improved for specific pathogens using polymerase chain reaction or antigen detection, especially for Streptococcus pneumoniae, Streptococcus pyogenes and Staphylococcus aureus. In a study including 78 children with pleural empyema, the causative micro-organism could be identified using direct culture of fresh pleural fluid in 45% of patients, with an additional 28% using PCR on pleural fluid of negative cultures. Pneumococcal antigen detection in pleural fluid samples by latex agglutination can also be useful for rapid diagnosis of pneumococcal empyema. In the previously noted study, positive and negative predictive value of pneumococcal antigen detection was 95% and 90%, respectively. However, despite the additional diagnostic value of these tests, PCR and antigen detection have limited value in determining treatment choice because of the lack of information on antibiotic resistance.

Chest radiography is the preferred means of initial diagnosis for hemothorax. Upright radiography is preferred but supine films may be taken when upright radiography is not feasible due to the clinical situation. Tube thoracostomy may be done prior to imaging when patients have sustained blunt or penetrating thoracic trauma and display unstable hemodynamics, have respiratory failure with absent or decreased breath sounds, show tracheal deviation, or have serious penetrating injuries. In upright radiography, hemothorax is suggested by blunting of the costophrenic angle or partial or complete opacification of the hemithorax, in which the lateral side of the chest appears bright and the lung appears pushed away toward the center; the air-filled lung normally appears as a dark space on radiographic film. In the case of a small hemothorax, several hundred milliliters of blood can be hidden by the diaphragm and abdominal viscera. In supine patients, signs of hemothorax may also be subtle on radiographic film, because the blood will layer in the pleural space, and can be seen as a haziness in one half of the thorax relative to the other side.

Ultrasonography is also used for detection of hemothorax and other pleural effusions, particularly in the critical care and trauma settings, because it provides rapid, reliable results in order to make a diagnosis in an emergency situation. Computed tomography (CT or CAT) scans can detect much smaller amounts of fluid than chest radiography, but computed tomography is not a primary method of diagnosis within the trauma setting, due to the time required for imaging, the requirement that a patient remain supine, and the need to transport a critically ill patient to the scanner.

When a thymoma is suspected, a CT/CAT scan is generally performed to estimate the size and extent of the tumor, and the lesion is sampled with a CT-guided needle biopsy. Increased vascular enhancement on CT scans can be indicative of malignancy, as can be pleural deposits. Limited biopsies are associated with a very small risk of pneumomediastinum or mediastinitis and an even-lower risk of damaging the heart or large blood vessels. Sometimes thymoma metastasize for instance to the abdomen.

The diagnosis is made via histologic examination by a pathologist, after obtaining a tissue sample of the mass. Final tumor classification and staging is accomplished pathologically after formal surgical removal of the thymic tumor

Selected laboratory tests can be used to look for associated problems or possible tumor spread. These include: full blood count, protein electrophoresis, antibodies to the acetylcholine receptor (indicative of myasthenia), electrolytes, liver enzymes and renal function.

Diagnosis relies on the characteristic cytopathology of the exudative pleural fluid, which contains elongated and giant multinucleated macrophages in a sea of amorphous granular material. The absence of mesothelial cells is also characteristic (Champion, 1968). While these findings are highly specific for rheumatoid pleuritis (Nosanchuk et al., 1968; Geisinger, 1985; Engel, 1986; Montes, 1988; Shinto, 1988), rheumatoid pleuritis must be considered if more than one of the above cytologic findings are detected.

Cancer screening uses medical tests to detect disease in large groups of people who have no symptoms. For individuals with high risk of developing lung cancer, computed tomography (CT) screening can detect cancer and give a person options to respond to it in a way that prolongs life. This form of screening reduces the chance of death from lung cancer by an absolute amount of 0.3% (relative amount of 20%). High risk people are those age 55–74 who have smoked equivalent amount of a pack of cigarettes daily for 30 years including time within the past 15 years.

CT screening is associated with a high rate of falsely positive tests which may result in unneeded treatment. For each true positive scan there are about 19 falsely positives scans. Other concerns include radiation exposure and the cost of testing along with follow up. Research has not found two other available tests—sputum cytology or chest radiograph (CXR) screening tests—to have any benefit.

The United States Preventive Services Task Force (USPSTF) recommends yearly screening using low-dose computed tomography in those who have a total smoking history of 30 pack-years and are between 55 and 80 years old until a person has not been smoking for more than 15 years. Screening should not be done in those with other health problems that would make treatment of lung cancer if found not an option. The English National Health Service was in 2014 re-examining the evidence for screening.

Since GISTs arise from the bowel layer called muscularis propria (which is deeper to the mucosa and submucosa from a luminal perspective), small GIST imaging usually suggest a submucosal process or a mass within the bowel wall. In barium swallow studies, these GISTs most commonly present with smooth borders forming right or obtuse angles with the nearby bowel wall, as seen with any other intramural mass. The mucosal surface is usually intact except for areas of ulceration, which are generally present in 50% of GISTs. Ulcerations fill with barium causing a bull's eye or target lesion appearance. In contrast-enhanced CT, small GISTs are seen as smooth, sharply defined intramural masses with homogeneous attenuation.

Ferner et al. give the following diagnostic criteria for Schwannomatosis:

- Definite

- Age >30 years and ≥2 nonintradermal schwannomas, at least one with histologic confirmation and no evidence of vestibular tumor on MRI scan and no known NF mutation, or

- One nonvestibular schwannoma plus a first-degree relative with schwannomatosis

- Possible

- Age <30 and ≥2 nonintradermal schwannomas, at least one with histologic confirmation and no evidence of vestibular tumor on MRI scan and no known NF mutation, or

- Age >45 and ≥2 nonintradermal schwannomas, at least one with histologic confirmation and no symptoms of 8th nerve dysfunction and no NF2, or

- Nonvestibular schwannoma and first-degree relative with schwannomatosis

- Segmental. Diagnosed as definite or possible but limited to one limb or ≤5 contiguous segments of spine.

Another set of criteria are:

- Two or more nonintradermal (cutaneous) schwannomas

- No evidence of vestibular tumor

- No known NF-2 mutation

or

- One pathologically confirmed nonvestibular schwannoma plus a first degree relative who meets the above criteria.

Clear diagnosis is useful to avoid unnecessary treatment and exclude more sinister diagnoses (for example, haemoptysis or pleural effusion could also indicate cancer). Overall treatment for pulmonary endometriosis is surgical, with subsegmentectomy. It is obviously important to preserve as much lung parenchyma as possible, while removing macroscopic signs of pathological tissue. Medical treatment includes gonadotropin-releasing hormone analogues, which can cause cessation of menstruation and decreased libido, as well as a 50% recurrence rate. Even in the asymptomatic, treatment is recommended to prevent possible complications listed above.

Steroids are the mainstay of treatment for rheumatoid arthritis, and have been shown to improve rheumatoid pleuritis. This would seem to be an outdated view of the treatment for this disease. More modern methods form the mainstay of treatment today. (no references?)