Malignant pleural effusion is a condition in which

cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal bl ...

causes an abnormal amount of fluid to collect between the thin layers of tissue (

pleura The pulmonary pleurae (''sing.'' pleura) are the two opposing layers of serous membrane overlying the lungs and the inside of the surrounding chest walls. The inner pleura, called the visceral pleura, covers the surface of each lung and dips ...

) lining the outside of the lung and the wall of the

chest cavity The thoracic cavity (or chest cavity) is the chamber of the body of vertebrates that is protected by the thoracic wall ( rib cage and associated skin, muscle, and fascia). The central compartment of the thoracic cavity is the mediastinum. Ther ...

Lung cancer Lung cancer, also known as lung carcinoma (since about 98–99% of all lung cancers are carcinomas), is a malignant lung tumor characterized by uncontrolled cell growth in tissues of the lung. Lung carcinomas derive from transformed, malign ...

and

breast cancer Breast cancer is cancer that develops from breast tissue. Signs of breast cancer may include a lump in the breast, a change in breast shape, dimpling of the skin, milk rejection, fluid coming from the nipple, a newly inverted nipple, or ...

account for about 50-65% of malignant pleural effusions. Other common causes include pleural mesothelioma and

lymphoma Lymphoma is a group of blood and lymph tumors that develop from lymphocytes (a type of white blood cell). In current usage the name usually refers to just the cancerous versions rather than all such tumours. Signs and symptoms may include enl ...

Diagnosis

Clinical evaluation

Clinical factors predicting the diagnosis of malignant pleural effusions are symptoms lasting more than 1 month and the absence of fever.

Imaging

This is needed to confirm the presence of a

pleural effusion A pleural effusion is accumulation of excessive fluid in the pleural space, the potential space that surrounds each lung. Under normal conditions, pleural fluid is secreted by the parietal pleural capillaries at a rate of 0.6 millilitre per ...

Chest radiograph A chest radiograph, called a chest X-ray (CXR), or chest film, is a projection radiograph of the chest used to diagnose conditions affecting the chest, its contents, and nearby structures. Chest radiographs are the most common film taken in me ...

is usually performed first and may demonstrate an underlying lung cancer as well as the pleural effusion.

Ultrasound Ultrasound is sound waves with frequencies higher than the upper audible limit of human hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies fr ...

has a sensitivity of 73% and specificity of 100% at distinguishing malignant pleural effusions from other causes of pleural effusion, based on the presence of visible pleural metastases, pleural thickening greater than 1 cm, pleural nodularity, diaphragmatic thickening measuring greater than 7mm and an echogenic swirling pattern visible in the pleural fluid.

Biochemical analysis

Malignant pleural effusions are

exudates An exudate is a fluid emitted by an organism through pores or a wound, a process known as exuding or exudation. ''Exudate'' is derived from ''exude'' 'to ooze' from Latin ''exsūdāre'' 'to (ooze out) sweat' (''ex-'' 'out' and ''sūdāre'' 'to ...

. A low pleural fluid pH is associated with poorer survival and reduced pleurodesis efficacy.

Histopathology

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%.

Biomarkers

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.

Treatment

The goal of treatment of malignant pleural effusions is relief of shortness of breath. 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 Small-cell carcinoma is a type of highly malignant cancer that most commonly arises within the lung, although it can occasionally arise in other body sites, such as the cervix, prostate, and gastrointestinal tract. Compared to non-small cell ca ...

. Simple aspiration of pleural fluid can relieve shortness of breath rapidly but fluid and symptoms will usually recur within a couple of weeks. Drainage should generally be done under ultrasound guidance. For this reason, more permanent treatments are usually used to prevent fluid recurrence. Standard treatment involves inserting an indwelling plural catheter and

pleurodesis Pleurodesis is a medical procedure in which part of the pleural space is artificially obliterated. It involves the adhesion of the visceral and the costal pleura. The mediastinal pleura is spared. Uses Pleurodesis is performed to prevent recurre ...

. 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. If an infection due to the catheter occurs, antibiotics are given and the catheter is generally left in. A Cochrane review concluded tentatively in favour of thoracoscopy to remove the fluid and blow talc into the pleural cavity (talc poudrage) compared to other commonly used methods.

References

External links

{{Respiratory pathology Diseases of pleura