Malignant pleural effusions

Various diseases of the gastrointestinal tract at times are accompanied by an exudative pleural effusion. The exudative pleural effusions resulting from esophageal perforation, pancreatic disease, subphrenic abscess, intrahepatic abscess, splenic abscess, abdominal operations, and diaphragmatic hernia are discussed in this article.     

Malignant pleural effusions

The estimated annual incidence of malignant pleural effusions in the United States is 150,000 cases. Patients most commonly present with dyspnea, initially on exertion and later at rest. Chemical pleurodesis is the most common modality of therapy for patients with recurrent, symptomatic, malignant pleural effusion. Talc is the most successful pleurodesis agent, and talc poudrage and slurry have equal efficacy. Although a number of cases of acute respiratory failure have been associated with talc pleurodesis, the incidence is < 1% and many of these episodes cannot be clearly attributed to talc alone. Although a low pleural fluid pH is associated with a decreased survival and less successful pleurodesis, pH should not be the sole criterion for recommending or withholding pleurodesis. Other factors that need to be considered before recommending pleurodesis include relief of dyspnea after therapeutic thoracentesis, general health of the patient, performance status, presence of trapped lung, and the primary malignancy. Pleuroperitoneal shunt or chronic indwelling catheter should be considered for patients who fail pleurodesis or who have a trapped lung.     

Malignant pleural effusions. A clinical cytopathologic study

From 1978 to 1982, 620 pleural fluid cytology specimens were examined, of which 80 were positive in 64 patients. Of these 64, three (0.5%) specimens had false-positive results. Adenocarcinoma of the lung was the most frequent (25 of 61) primary site, followed by breast (12 of 61), ovary (six of 61), and pancreas (five of 61). Comparing cytology with pleural core needle biopsy specimens in 26 patients, the cytology results were positive in 96%, while the needle biopsy specimens alone were positive in only 69%. Following the diagnoses of malignant pleural effusions, the patients receiving combined chemotherapy and radiotherapy had a mean survival of 328 days, compared with only 79 days for those who received no therapy. In conclusion, cytologic examination of Papanicolaou-stained smears yielded a greater percentage of positive diagnoses than either cell block preparations or pleural needle biopsy specimens. Over the past 25 years, the mean survival after the diagnosis of malignant pleural effusions has shown no improvement.     

Malignant pleural effusions: treatment with tunneled long-term drainage catheters

Malignant pleural effusion is a significant cause of morbidity and a poor prognostic indicator. Traditional treatments have variable success and significant drawbacks, including a length of stay in the hospital. Alternatively, a tunneled pleural catheter permits long-term drainage as an outpatient, cost-effectively controlling the effusion and related symptoms in over 80 to 90% of patients. Other advantages are the ability to treat trapped lungs and large locules. Spontaneous pleurodesis may occur in over 40% of patients, and the catheter can be used to administer sclerosant or antineoplastic agents. Complications tend to be minor and easily managed. A tunneled pleural catheter should be considered for all patients with MPE having a reasonable expectancy of being an outpatient.     

Lipid pleural effusions

Traditionally, a lipid pleural effusion has been described as milky or turbid appearing. However, lipid effusions may have varied presentations making a diagnosis by appearance problematic. Distinguishing between a chylothorax and a cholesterol effusion, the 2 types of lipid effusions, is essential. A chylothorax develops after injury or obstruction of the thoracic duct, leading to a chyle leak into the pleural space that is characterized by an increased triglyceride concentration and the presence of chylomicrons. In contrast, a cholesterol effusion is a long-standing effusion associated with an elevated cholesterol concentration, usually greater than 250 mg/dL, a thick pleural rind, and represents a form of lung entrapment.     

Tuberculous pleural effusions

While a number of recent reports have documented the changing clinical and radiographic spectrum of parenchymal tuberculosis, relatively little attention has been paid to changes in the patterns of pleural tuberculosis. We therefore reviewed the clinical, laboratory, and radiographic characteristics of 26 adult patients with tuberculous pleural effusions. We found that pleural tuberculosis has become a disease of older adults (median age, 56 years) and that 19 percent (5/26) of the cases were due to postprimary (reactivation) disease. This shift in age led to problems in diagnosis, since many of these older patients had underlying or coexisting disease that could have caused a pleural effusion. Both specimens of pleural fluid and pleural biopsy were useful in establishing the diagnosis. Examination of sputum was less helpful. All patients who were not anergic had positive cutaneous reactions to first-strength purified protein derivative of tuberculin. Lymphocytosis of the pleural fluid was not a uniform finding; only 62 percent of our patients had greater than 50 percent lymphocytes on their initial examinations of pleural fluid, and four patients had greater than 90 percent polymorphonuclear cells. All of the effusions were exudates, and four had glucose levels in the pleural fluid that were less than 30 mg/dl. Pleural tuberculosis is an important diagnostic consideration in adult or elderly patients with exudative pleural effusions.     

Transudative pleural effusions

A transudative pleural effusion develops when the systemic factors influencing the formation or absorption of the pleural fluid are altered. The pleural surfaces are not involved by the primary pathologic process. The diagnosis of transudative effusion is simple to establish by examining the characteristics of the pleural fluid. Transudates have all of the following three characteristics: The ratio of the pleural fluid to the serum protein is less than 0.5. The ratio of the pleural fluid to the serum LDH is less than 0.6. The pleural fluid LDH is less than two thirds the upper limit of normal for the serum LDH. Among the conditions that produce transudative pleural effusion, congestive heart failure is by far the most common. Pulmonary embolism, cirrhosis of the liver with ascites, and the nephrotic syndrome are the other common causes. Management of transudative pleural effusions involves managing the primary disease. Refractory, massive effusions can be controlled by tetracycline pleurodesis.     

Tuberculous pleural effusions

Tuberculosis is the most frequent cause of death due to infectious diseases. In Europe, it is one of the most frequent types of pleural effusions in young patients. Tuberculosis is caused by the rupture of a pulmonary subpleural caseous focus, which releases mycobacterium into the pleural cavity, thereby triggering an immune response involving mainly macrophages, CD4+ T lymphocytes, and the cytokines released by these cells (especially interleukin 1, interleukin 2, and ?-interferon). In recent years, classical microbiological and histological methods of diagnosis have been joined by biochemical analyses of pleural fluid, which are faster and can be more sensitive. In particular, tuberculous effusions have high adenosine deaminase (ADA) activity, apparently due to high levels of the ADA isoenzyme ADA2, which is only found in monocytes and macrophages (although certain data suggest the possible involvement of activated T cells, too). It has been recommended that treatment for tuberculosis be initiated if analysis of pleural fluid shows high ADA activity, a lymphocyte/neutrophil ratio greater than 0.75, and no malignant cells. Another highly efficient marker is ?-interferon, which is released by activated CD4+ T cells, but its high price is an obstacle to its routine determination in clinical practice. Identification of mycobacterial DNA by means of the polymerase chain reaction (PCR) is less efficient, apparently because its sensitivity depends heavily on mycobacterium concentration. No other biochemical parameters currently appear to be of marked relevance for the diagnosis of tuberculous pleural effusion (TPE). TPE responds well to the standard treatment for tuberculosis. However, 50% of TPE patients have a thickened pleura as a result of the accumulation of fluid, and in 16% the quantity of effusion increases during treatment, even if corticosteroids are administered. It therefore seems reasonable for treatment with antituberculous drugs to be preceded by therapeutic thoracocentesis to remove as much fluid as possible.     

Eosinophilic pleural effusions

Eosinophilic pleural effusions, defined as a pleural effusion that contains at least 10% eosinophils, may be caused by almost every condition that can cause pleural disease. Eosinophilic pleural effusion occurs most commonly during conditions associated with the presence of blood or air in the pleural space, infections, and malignancy. Drug-induced pleural effusions, pleural effusions accompanying pulmonary embolism, and benign asbestos pleural effusions are also among the common causes of eosinophilic pleural effusion. No etiology is found in as many as one third of patients. Because studies evaluating different diagnostic approaches with eosinophilic pleural effusions are lacking, the authors suggest that certain noninvasive and invasive diagnostic tools must be used based on the patient's clinical characteristics.     

Hypothyroidism and pleural effusions

Serous effusions have been thought to be an unusual complication of hypothyroidism and most commonly have been associated with ascites, pericardial fluid and heart failure. Pleural fluid as an isolated finding in hypothyroidism is apparently rare and complete analysis of these hypothyroid-associated pleural effusions has not been described. To determine the frequency, chemical characteristics and clinical associations of hypothyroidism and pleural effusions, the medical records of 128 patients with hypothyroidism (defined by an increased serum TSH concentration) were reviewed. The majority of effusions in patients with hypothyroidism were due to other diseases. Effusions solely due to hypothyroidism appeared to be a real entity. These effusions were borderline between exudates and transudates and showed little evidence of inflammation.     

Atypical tuberculous pleural effusions

Typically, a tuberculous pleural effusion is submassive, unilateral, and has the appearance of a clear straw coloured fluid with a cellular content predominantly consisting of lymphocytes. Atypical characteristics of tuberculous pleural effusion do, however, need to be recognised to mitigate the risk of delayed diagnosis, the latter sometimes resulting in potentially avoidable deaths, and also to reduce the risk that untreated patients might transmit the disease.