Chapter 137: Diseases of the Pleura

PLEURAL EFFUSION

Pleural effusion is defined as excess fluid accumulation in the pleural space. Pleural effusions are typically detected by chest imaging (radiograph or CT); chest ultrasound can guide thoracentesis procedures. The two major classes of pleural effusions are transudates, which are caused by systemic influences on pleural fluid formation or resorption, and exudates, which are caused by local influences on pleural fluid formation and resorption. Common causes of transudative effusions are left ventricular heart failure, cirrhosis, and nephrotic syndrome. Common causes of exudative effusions are bacterial pneumonia, malignancy, viral infection, and pulmonary embolism. A more comprehensive list of the etiologies of transudative and exudative pleural effusions is provided in Table 137-1. Additional diagnostic procedures are indicated with exudative effusions to define the cause of the local disease.

TABLE 137-1: Differential Diagnoses of Pleural Effusions

Transudative Pleural Effusions

  1. Congestive heart failure
  2. Cirrhosis
  3. Nephrotic syndrome
  4. Peritoneal dialysis
  5. Superior vena cava obstruction
  6. Myxedema
  7. Urinothorax

Exudative Pleural Effusions

  1. Neoplastic diseases
    1. Metastatic disease
    2. Mesothelioma
  2. Infectious diseases
    1. Bacterial infections
    2. Tuberculosis
    3. Fungal infections
    4. Viral infections
    5. Parasitic infections
  3. Pulmonary embolism
  4. Gastrointestinal disease
    1. Esophageal perforation
    2. Pancreatic disease
    3. Intraabdominal abscess
    4. Diaphragmatic hernia
    5. After abdominal surgery
    6. Endoscopic variceal sclerotherapy
    7. After liver transplant
  5. Collagen-vascular diseases
    1. Rheumatoid pleuritis
    2. Systemic lupus erythematosus
    3. Drug-induced lupus
    4. Sjögren syndrome
    5. Granulomatosis with polyangiitis (Wegener’s)
    6. Churg-Strauss syndrome
  6. Post-coronary artery bypass surgery
  7. Asbestos exposure
  8. Sarcoidosis
  9. Uremia
  10. Meigs’ syndrome
  11. Yellow nail syndrome
  12. Drug-induced pleural disease
    1. Nitrofurantoin
    2. Dantrolene
    3. Methysergide
    4. Bromocriptine
    5. Procarbazine
    6. Amiodarone
    7. Dasatinib
  13. Trapped lung
  14. Radiation therapy
  15. Post-cardiac injury syndrome
  16. Hemothorax
  17. Iatrogenic injury
  18. Ovarian hyperstimulation syndrome
  19. Pericardial disease
  20. Chylothorax

Exudates fulfill at least one of the following three criteria: high pleural fluid/serum protein ratio (>0.5), pleural fluid lactate dehydrogenase (LDH) greater than two-thirds of the laboratory normal upper limit for serum LDH, or pleural/serum LDH ratio >0.6. Transudative effusions typically do not meet any of these criteria. However, these criteria misidentify about 25% of transudates as exudates. For exudative effusions, pleural fluid should also be tested for pH, glucose, white blood cell count with differential, microbiologic studies, and cytology. An algorithm for determining the etiology of a pleural effusion is presented in Fig. 137-1.

FIGURE 137-1
hmom20_ch137_f001.png
Approach to the diagnosis of pleural effusions. CHF, congestive heart failure; CT, computed tomography; LDH, lactate dehydrogenase; PE, pulmonary embolism; PF, pleural fluid; TB, tuberculosis.

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