Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (595 page)

   Constrictive pericarditis—effusion is bilateral

   Urinothorax—due to ipsilateral GU tract obstruction

Exudate

   Pneumonia, malignancy, pulmonary embolism, and gastrointestinal conditions (especially pancreatitis and abdominal surgery) cause 90% of all exudates. The cause is unknown in approximately 10–15% of all exudates.

   Causes

   Infection (25% of cases): bacterial pneumonia; parapneumonic effusion (empyema); TB; abscess (subphrenic, liver, spleen); viral, mycoplasmal, rickettsial; parasitic (ameba, hydatid cyst, filaria); fungal effusion (
Coccidioides, Cryptococcus, Histoplasma, Blastomyces, Aspergillus
; in immunocompromised hosts:
Aspergillus, Candida, Mucor
)

   PE/infarction

   Neoplasms (metastatic carcinoma, especially breast, ovary, and lung; lymphoma; leukemia; mesothelioma; pleural endometriosis) (42% of cases)

   Trauma (penetrating or blunt): hemothorax, chylothorax, and empyema, associated with rupture of diaphragm

   Immunologic mechanisms: rheumatoid pleurisy (5% of cases), SLE; other collagen vascular diseases occasionally cause effusions (e.g., Wegener granulomatosis, Sjögren syndrome, familial Mediterranean fever, Churg-Strauss syndrome, mixed connective tissue disease); following myocardial infarction or cardiac surgery; vasculitis; hepatitis; sarcoidosis (rare cause; may also be transudate); familial recurrent polyserositis; drug reaction (e.g., nitrofurantoin hypersensitivity, methysergide)

   Chemical mechanisms: uremic, pancreatic (pleural effusion occurs in approximately 10% of these cases), esophageal rupture (high salivary amylase and pH <7.30 that approaches 6.00 in 48–72 hours), subphrenic abscess

   Lymphatic abnormality (e.g., irradiation, Milroy disease)

   Injury (e.g., asbestosis)