Table 1.

Highlights on pleural effusion etiology.

Pleural Infection	6.7–9.9 cases/100,000 population Mortality of almost 20% at 12 months Principal pleural infections: Staphylococcus aureus, viridans-group Streptococci, Streptococcus pneumoniae, Enterobacteriaceae and Pseudomonas species Empyema shows the longer hospitalization stay and the higher cost between pleural effusion hospitalizations.
Abdominal Etiologies	5–15% of patients with cirrhosis suffer from hepatic hydrothorax Acute pancreatitis patients will present pleural effusion in half of the cases Chronic renal failure is associated with pleural effusion in almost 7% of patients
Connective Tissue Diseases	Incidence of pleural effusion is reported in 5–20% of rheumatoid arthritis patients, 17–60% of systemic lupus erythematosus patients, in 5–55% of granulomatosis with polyangiitis patients and in 7% of systemic sclerosis patients
IgG4-Related Disease	Thoracic involvement in almost half of the cases
Amyloidosis	Pleural effusion may be present in almost 40% of patients

For details see Section 3.