Pleural empyema due to ruptured amoebic liver abscess

Pleural effusion: diagnosis, treatment, and management

A pleural effusion is an excessive accumulation of fluid in the pleural space. It can pose a diagnostic dilemma to the treating physician because it may be related to disorders of the lung or pleura, or to a systemic disorder. Patients most commonly present with dyspnea, initially on exertion, predominantly dry cough, and pleuritic chest pain. To treat pleural effusion appropriately, it is important to determine its etiology. However, the etiology of pleural effusion remains unclear in nearly 20% of cases. Thoracocentesis should be performed for new and unexplained pleural effusions. Laboratory testing helps to distinguish pleural fluid transudate from an exudate. The diagnostic evaluation of pleural effusion includes chemical and microbiological studies, as well as cytological analysis, which can provide further information about the etiology of the disease process. Immunohistochemistry provides increased diagnostic accuracy. Transudative effusions are usually managed by treating the underlying medical disorder. However, a large, refractory pleural effusion, whether a transudate or exudate, must be drained to provide symptomatic relief. Management of exudative effusion depends on the underlying etiology of the effusion. Malignant effusions are usually drained to palliate symptoms and may require pleurodesis to prevent recurrence. Pleural biopsy is recommended for evaluation and exclusion of various etiologies, such as tuberculosis or malignant disease. Percutaneous closed pleural biopsy is easiest to perform, the least expensive, with minimal complications, and should be used routinely. Empyemas need to be treated with appropriate antibiotics and intercostal drainage. Surgery may be needed in selected cases where drainage procedure fails to produce improvement or to restore lung function and for closure of bronchopleural fistula.

Thoracic amebiasis

Pleuropulmonary amebiasis is the common and pericardial amebiasis the rare form of thoracic amebiasis. Low socioeconomic conditions, malnutrition, chronic alcoholism, and ASD with left to right shunt are contributing factors to the development of pulmonary amebiasis. Although no age is exempt, it commonly occurs in patients aged 20 to 40 years, with an adult male to female ratio of 10:1. Children rarely develop thoracic amebiasis: when it does occur there is an equal sex distribution. The infection usually spreads to the lungs by extension of an amebic liver abscess. Infection may pass to the thorax directly from the primary intestinal lesion through hematogenous spread, however. Lymphatic spread is one possible route. Inhalation of dust containing cysts and aspiration of cysts or trophozoites of E histolytica in the lungs are some other hypothetical routes. The lung is the second most common extraintestinal site of amebic involvement after the liver. Usually the lower lobe, and sometimes the middle lobe of the right lung, are affected, but it may affect any lobe of the lungs. The patient develops fever and right upper quadrant pain that is referred to the tip of the right shoulder or in between the scapula. Hemophtysis is common. The diagnosis of thoracic amebiasis is suggested by the combination of an elevated hemidiaphragm (usually right), hepatomegaly, pleural effusion, and involvement of the right lung base in the form of haziness and obliteration of costophrenic and costodiaphragmatic angles. Infection is usually extended to the thorax by perforation of a hepatic abscess through the diaphragm and across an obliterated pleural space, producing pulmonary consolidation, abscesses, or broncho-hepatic fistula. Empyema develops when a liver abscess ruptures into the pleural space. Rarely, a posterior amebic liver abscess can burst into the inferior vena cava and develop an embolism of the inferior vena cava and thromboembolic disease of the lungs with congestive cardiac failure or corpulmonale. Diagnosis by finding E histolytica in stool specimens is of limited value. In a limited number of cases amebae might be found in aspirated pus or expectorated sputum. "Anchovy sauce-like" pus or sputum may be found. Presence of bile in sputum indicates that the pus is of liver origin. Serological tests are of immense value in diagnosis. Liver enzymes are usually normal and neutrophilic leucocytosis may or may not be found. ESR is invariably elevated. Anti-amebic antibodies can be detected by ELISA, IFAT, and IHA. Amebic antigen can be detected from serum and pus by ELISA. Detection of Entamoeba DNA in pus or sputum may be a sensitive and specific method. Pleuropulmonary amebiasis is easily confused with other illnesses and is treated as pulmonary TB, bacterial lung abscesses, and carcinoma of the lung. A single drug regimen with metronidazole with supportive therapy usually cures patients without residual anomalies. Aspiration of pus from empyema thoracis may be needed for confirmation and therapeutic purposes. The pericardium is usually involved by direct extension from the amebic abscess of the left lobe of the liver, sometimes from the right lobe of the liver, and rarely from the lungs or pleura. An initial accumulation of serous fluid due to reactive pericarditis followed by intrapericardial rupture may develop either (1) acute onset of severe symptoms with chest pain, dyspnea, and cardiac tamponade, shock, and death, or (2) progressive effusion with thoracic cage pain, progressive dyspnea, and fever. Chest radiograph, ultrasound examination, and CT scan usually confirm the presence of a liver abscess in continuity with the pericardium and fluid within the pericardial sac with or without the fistulous tract. Echocardiography may demonstrate fluid in the pericardial cavity. Patients should be cared for in the ICU and ambecides should be started without delay. Pericardiocentesis usually confirms the diagnosis and improves the general condition of the patient. Aspiration of the accumulated fluid should be performed urgently in cardiac tamponade; repeated aspiration may be needed. Surgical drainage should be done if needed. Acanthamoeba, a free-living ameba, may also infect the lungs in the form of pulmonary nodular infiltration and pulmonary edema in association with amebic meningoencephalitis in immunocompromised patients. It usually spreads to the meninges of the brain by way of the blood from its primary lesion in the lung or skin. Early diagnosis and institution of treatment may be life saving for these patients. A literature review shows that HIV/AIDS patients are not prone to infection with E histolytica. It is now clear that there are an increasing number of HIV-seropositive patients among amebic liver abscess patients, however, which suggests that although the incidence of intestinal infection is not high among HIV-seropositive or AIDS patients they are more susceptible to an invasive form of the disease.

Pleural diseases

In the United States, approximately one million patients each year develop a pleural effusion. Pleural effusions have classically been divided into transudative and exudative pleural effusions. A transudative pleural effusion occurs when the systemic factors influencing pleural fluid formation and reabsorption are altered so that pleural fluid accumulates; an exudative pleural effusion occurs when the local factors influencing pleural fluid formation and reabsorption are altered, allowing accumulation of pleural fluid. The leading causes of transudative pleural effusions are left ventricular failure and cirrhosis with ascites. The leading causes of exudative pleural effusions are pneumonia, malignancy, and pulmonary embolization. Transudative pleural effusions can be differentiated from exudative pleural effusions by measurement of the pleural fluid protein and lactic dehydrogenase (LDH) levels. The ratio of the pleural fluid protein to the serum protein is less than 0.5, the ratio of the pleural fluid LDH to the serum LDH is less than 0.6, and the absolute value of the pleural fluid LDH level is less than two thirds of the upper normal limit for serum with transudative pleural effusions while at least one of these criteria is not met with exudative effusions. Most patients who have a pleural effusion with congestive heart failure have left ventricular failure. It is believed that the transudation of the pulmonary interstitial fluid across the visceral pleura overwhelms the capacity of the lymphatics to remove the fluid. Most patients with cirrhosis who have a pleural effusion also have ascites. It is also believed that the pleural effusions form when fluid moves directly from the peritoneal cavity into the pleural cavity through pores in the diaphragm. Approximately 40% of patients with pneumonia will have a pleural effusion. If these patients have a significant amount of pleural fluid, a diagnostic thoracentesis should be performed. Chest tubes should be inserted if the pleural fluid is gross pus, if the Gram stain of the pleural fluid is positive, if the pleural fluid glucose level is below 40 mg/dl, or if the pleural fluid pH level is less than 7.00. If drainage with the chest tubes is unsatisfactory, either streptokinase or urokinase should be injected intrapleurally. If drainage is still unsatisfactory, a decortication should be considered. The three leading malignancies that have an associated pleural effusion are breast carcinoma, lung carcinoma, lymphomas and leukemias. The diagnosis of pleural malignancy is made most commonly with pleural fluid cytology; in recent years immunohistochemical tests have proved invaluable in differentiating benign from malignant pleural effusions.(ABSTRACT TRUNCATED AT 400 WORDS)

Intrathoracic Complications of Amoebic Liver Abscess

Amoebiasis is a world-wide parasitic infestation but is more prevalent and virulent in warm countries. Of 33 patients with amoebic liver abscess (ALA) seen over a 5-year period, 24 had intrathoracic complications. Management consisted mainly of the administration of the antiamoebic agent metronidazole (Flagyl), repeated needle aspiration of ALA and surgical drainage when aspiration failed. Closed tube thoracostomy was the preferred management of amoebic empyema. Associated cerebral involvement in 4 cases improved with parenteral metronidazole. Pericardial amoebic abscess claimed 100% mortality in our series.