Pleural effusion

Pleural effusion is the abnormal accumulation of fluid in the pleural cavity between the lining of the lungs and the thoracic cavity (i.e., the visceral and parietal pleurae). Normally, a small amount of pleural fluid is present, which helps lubricate the pleural cavity and facilitates lung movement within the thoracic space. An imbalance between the oncotic and hydrostatic forces that govern pleural fluid formation and lymphatic drainage can result in excessive fluid accumulation. Fluid that permeates into the pleural cavity through intact pulmonary vessels, e.g., in congestive heart failure (CHF), is called a transudate. Conversely, fluid that escapes into the pleural cavity through lesions in blood and lymph vessels, e.g., due to inflammation or tumors, is called an exudate. Pleural effusion is often diagnosed using chest x-ray and ultrasound, but chest CT may be used for very small effusions. Thoracentesis serves as both a diagnostic and therapeutic procedure: pleural fluid analysis can help identify the underlying cause and excess pleural fluid evacuation can provide symptomatic relief. Treatment of pleural effusion often focuses on treating the underlying condition.

An excessive amount of fluid between pleural layers that impairs the expansion of the lungs

Transudative effusions ^[2][3]

• Congestive heart failure
• Hepatic cirrhosis
• Nephrotic syndrome
• Protein-losing enteropathy
• Chronic kidney disease (Na⁺ retention)
• Rare causes
  • Superior vena cava obstruction
  • Myxedema

Exudative effusions ^[2][3]

• Infection
  • Pneumonia (parapneumonic effusion)
  • Tuberculosis
  • Pleural empyema
  • Parasitic illness (e.g., amebiasis, echinococcal disease)
• Malignancies
  • Lung cancer
  • Metastatic breast cancer
  • Lymphoma
  • Mesothelioma
  • Ovarian cancer
• Pulmonary embolism (PE)
• Autoimmune disease (especially collagen vascular diseases)
  • Vasculitis
  • SLE
  • Rheumatoid arthritis
  • Sarcoidosis
• Trauma (high vascular permeability)
• Pancreatitis
• Hemothorax
• Chylothorax
• Pseudochylothorax
• Rare causes
  • Postcardiac surgery
  • Esophageal perforation
  • Gynecological causes
    • Endometriosis
    • Ruptured ectopic pregnancy
    • Meigs syndrome

Symptoms ^[3]

• Patients with a small pleural effusion (< 300 mL) are often asymptomatic.
• Characteristic symptoms
  • Dyspnea
  • Symptoms of hypoxia
  • Pleuritic chest pain (sharp retrosternal pain)
  • Dry, nonproductive cough
  • Symptoms of the underlying disease (e.g., fever in empyema, cachexia in cases of malignancy, symptoms of left-sided heart failure)

Physical exam findings

• Inspection and palpation
  • Asymmetric expansion and unilateral lagging on the affected side
  • Reduced tactile fremitus due to fluid in the pleural space
• Auscultation
  • Faint or absent breath sounds over the area of effusion
  • Pleural friction rub (squeaking sound of inflamed pleural layers rubbing together during inspiration and expiration)
• Percussion: dullness over the area of effusion

Approach

• Imaging is necessary to confirm the diagnosis.
• Consider diagnostic thoracentesis if the diagnosis is uncertain or management requires additional information (e.g., culture, cytology).
• Consider additional diagnostic procedures (e.g., bronchoscopy, VATS) if the diagnosis remains unclear.

Chest x-ray for pleural effusion ^[4][5]

• Indications
  • Standard initial imaging modality for detecting pleural effusion.
  • Lateral decubitus view (most sensitive): allows for detection of fluid collections as small as 5 mL ^[6]
• Supportive findings
  • Typically unilateral blunting of the costophrenic angle
  • Homogeneous density with a meniscus-shaped margin (meniscus sign)
  • Large effusion
    • Complete opacification of the lung
    • Mediastinal shift
    • Tracheal deviation away from the effusion (space-occupying lesion)
  • Disease-specific signs: See “Pleural empyema”, “Lung cancer”, “Active primary tuberculosis”, "Pneumonia diagnostics”, and “Pneumothorax.”

Supine CXR has poor sensitivity for pleural effusions, and effusions < 200 mL may not be visible on frontal upright CXR. Include lateral upright and lateral decubitus views whenever possible when obtaining radiographs. ^[3][4][6]

False positives for pleural effusions on CXR include elevated hemidiaphragm, atelectasis, consolidation, mass lesions.

Thoracic ultrasound for pleural effusion ^[4][7]

• Indications
  • Quick bedside assessment
  • Thoracentesis planning
• Procedure: See; “Lung POCUS” and “eFAST.”
• Ultrasound findings suggestive of pleural effusion: hypoechoic or anechoic collection in the lower margins of the pleural cavity (costodiaphragmatic recess)
  • Very sensitive: can detect fluid amounts as low as 20 mL
  • Hemothorax and empyema may appear heterogeneous.
  • Pleural fluid septations may be present.
  • Allows for detection of pleural thickening and pleural nodules

Thoracic ultrasound is more sensitive than chest x-ray for diagnosing effusions and estimating effusion size. ^[8]

False positives on ultrasound can result if the following are mistaken for pleural fluid: subdiaphragmatic fluid (e.g., ascites), pericardial fluid, contained fluid (e.g., hypoechoic masses, abscesses), or pleural thickening. False negatives may result if clotted blood or empyema fluid is mistaken for normal lung or liver tissue. ^[9]

Chest CT ^[4][7]

• Indications: gold standard ; for small effusions but use is limited because of radiation and contrast exposure
  • Guiding placement of indwelling pleural catheters
  • Directed thoracentesis of a loculated effusion
  • Suspected parenchymal or pleural pathology
  • Better quantification of the amount of fluid (compared to CXR) is desired
• Procedure: chest CT without IV contrast is usually sufficient
  • With IV contrast: allows for the detection of underlying malignancy (e.g., metastases and/or primary tumor)
  • CT angiogram: helps to identify vascular pathology (e.g., dissection or AVM)
• Supportive findings
  • Can detect > 3–5 mL of fluid
  • Fluid density measurement can help differentiate pleural effusion from empyema and hemothorax ^[10]
  • Disease-specific signs: See “Pleural empyema.”

Diagnostic thoracentesis ^[3][11]

Can be combined with therapeutic thoracentesis if both are indicated. See “Thoracentesis” for detailed indications, contraindications, procedural steps, and complications.

• Goal: obtain samples for pleural fluid analysis, e.g., to differentiate transudates from exudates, and identify the underlying cause of pleural effusion
• Indications: include new unilateral pleural effusions and bilateral effusions with atypical features (e.g., fever, chest pain, variable size).
• Routine pleural fluid studies
  • Biochemistry: protein, LDH, pH, and glucose
  • Gram stain and culture
  • Cytology
• Serum studies (for comparison): serum protein, LDH, pH, and glucose
• Advanced pleural fluid studies (case by case)
  • Cell count
  • Lipids: cholesterol, triglycerides
  • Amylase, lipase
  • TB testing: adenosine deaminase, AFB smear microscopy
  • Parasitology
  • Tumor markers
  • Rheumatological markers
  • NT-proBNP

Additional studies ^[6]

• Laboratory studies: may be indicated further workup of transudative effusions.
  • Elevated serum NT-proBNP: suggests heart failure
  • ↑ Liver transaminases, ↓ serum albumin, and abnormal coagulation studies: suggests cirrhosis
  • Proteinuria: suggests nephrotic syndrome
  • ↑ Serum TSH: suggests hypothyroidism
• Invasive tests: Consider for patients with inconclusive pleural fluid analysis to rule out malignancy or intracellular infection.
  • Bronchoscopy
  • Percutaneous needle biopsy
  • VATS

Differentiating transudates from exudates ^{[3][6][7][12][13]}

Light criteria are useful for ruling out an exudate if all criteria are assessed as the sensitivity is high. They are less reliable for ruling in an exudate as the specificity is poor and can misclassify ∼ 25% of transudates as exudates. Interpret results taking the full clinical picture into account. ^[6][14]

Narrowing the differential diagnosis of exudative effusions ^[3][7][13]

Transudate is usually clear, has a decreased cell count, and has low levels of protein, albumin, and LDH. Exudate typically appears cloudy, has an increased cell count, and has high levels of protein, albumin, and LDH.

MEAT has low glucose: Malignancy, Empyema, Arthritis (rheumatoid pleurisy), and Tuberculosis are causes of pulmonary effusion associated with low glucose levels.

Pleural fluid with a bloody appearance suggests a malignant etiology or hemothorax!

• Lung densities on imaging
  • Lung mass, e.g., bronchial carcinoma, lung metastasis
  • Pneumonia
  • Interstitial lung disease
  • Atelectasis
• Pleural densities on imaging
  • Metastatic disease
  • Pleural fibrosis or scarring
  • Pleural mesothelioma
• Other mimics
  • Subphrenic abscess
  • Pneumothorax
  • Diaphragmatic hernia ^[17]

The differential diagnoses listed here are not exhaustive.

Approach ^[6][11][15]

• Unstable patients: e.g., respiratory distress, respiratory failure, or hemodynamic instability.
  • Begin respiratory support.
  • Perform urgent therapeutic thoracentesis.
• All patients
  • Identify and treat the underlying condition (see “Treatment of pleural effusion”).
  • Consider elective therapeutic thoracentesis based on individual risk-benefit ratios.
  • Consider specialized procedures and/or surgical therapy after specialty consultation.

Identify and treat life-threatening causes of pleural effusion, e.g., pulmonary embolism, esophageal rupture, and hemothorax.

Stabilization

• ABCDE survey
  • Oxygen therapy, mechanical ventilation, and immediate hemodynamic support as needed
  • Emergency blood transfusion for massive hemothorax ^[18]
  • Portable upright CXR or lung ultrasound to evaluate effusion size
• Urgent therapeutic thoracentesis indications
  • Respiratory distress signs
  • Hemodynamic compromise secondary to the effusion
• Management of life-threatening conditions
  • Esophageal rupture: Consult surgery and start empiric antibiotics.
  • Sepsis: Begin sepsis management.
  • Acute heart failure: Begin AHF management.

Next steps

• Clinical improvement (life-threatening causes ruled out)
  • Continue detailed clinical evaluation.
  • Obtain additional diagnostics for pleural effusion (e.g., CT chest, diagnostic thoracentesis).
• Clinical deterioration
  • Optimize oxygenation in mechanically ventilated patients
  • Consult a specialist for admission (e.g., critical care) and complicated pleural fluid drainage (e.g., pulmonology, interventional radiology, and/or thoracic surgery)

Disposition ^[4][19]

Unstable patients

• ICU admission
• Consider immediate OR transfer for massive hemothorax.

Stable patients

• Consider admission for: ^[20][21]
  • Parapneumonic effusion or empyema
  • Underlying disease requiring inpatient treatment
  • Large effusion of unknown etiology
• Consider observation and discharge after successful therapeutic thoracentesis in patients with a known and stable underlying condition and no complications.
• If thoracentesis is not indicated, consider discharge if all of the following are present:
  • Known and self-limited etiology of pleural effusion (e.g., recent abdominal surgery)
  • No signs of respiratory distress
  • Ability to adhere to discharge instructions and follow-up

• Provide supplemental oxygen as needed.
• If respiratory distress, respiratory failure, or hemodynamic instability is present, perform urgent therapeutic thoracentesis and consult ICU.
• Consider continuous cardiac monitoring and pulse oximetry.
• Obtain confirmatory imaging: e.g., CXR (upright PA and lateral, or lateral decubitus), lung ultrasound, CT chest.
• Obtain CBC, coagulation panel, serum protein, and LDH. .
• Correct coagulopathy if present.
• Perform diagnostic thoracentesis and pleural fluid analysis if new effusion or etiology is uncertain.
  • Routine studies: glucose, LDH, protein, cholesterol, and pH.
  • Consider additional studies depending on patient history and the suspected etiology: AFB smear microscopy, adenosine deaminase, amylase/lipase, rheumatoid factor, ANA, cytology, immunohistochemistry, Gram stain plus culture
• Repeat CXR after thoracentesis.
• Identify and treat the underlying cause (see “Pleural fluid analysis” and “Common causes of pleural effusion”).
• If empyema is suspected, administer empiric IV antimicrobial therapy for pleural infection.
• Consider elective therapeutic thoracentesis for large symptomatic effusions and complicated parapneumonic effusions.
• Monitor for reexpansion pulmonary edema if therapeutic thoracentesis is performed.
• Consider other types of pleural fluid drainage on an individual basis depending on etiology and recurrence risk after specialty constulation, e.g., indwelling pleural catheter, tube thoracostomy, or surgery.
• Consult thoracic surgery for chest tube insertion and/or surgery for suspected empyema and/or hemothorax.

Treatment of the underlying cause ^[6]

• Acute congestive heart failure: loop diuretics (see “Treatment of heart failure”)
• Collagen vascular diseases: steroids (see “Systemic lupus erythematosus” and “Rheumatoid arthritis”)
• Pancreatitis: See “Treatment of acute pancreatitis.”
• Pancreaticopleural fistula: Endoscopic or surgical intervention is recommended. ^[22][23][24]
• Meigs syndrome: Removal of the ovarian tumor is recommended.
• Other malignancy: targeted cancer immunotherapy, chemotherapy, radiotherapy, or surgical resection

Consider pulmonary embolism as a potential cause of unexplained effusion; anticoagulation therapy may be initiated even in the presence of blood-tinged pleural effusion. ^[25]

Therapeutic thoracentesis ^[11]

See “Thoracentesis” for detailed indications, contraindications, procedural steps, and complications.

• Goals: removal of pleural fluid that compromises cardiac and/or respiratory function and/or carries a risk of infection
• Indications include large symptomatic effusion (e.g., causing hemodynamic instability or respiratory failure), and complicated parapneumonic effusions.
• Complications include reexpansion pulmonary edema, infection, and injury.

Complicated parapneumonic effusions should be drained due to a high risk of progression to empyema.

Reexpansion pulmonary edema ^[26][27]

• Definition: Self-limiting noncardiogenic pulmonary edema that develops within 24 hours following rapid reexpansion of lung tissue that has collapsed as a result of air, pleural fluid, or mucus plugging; most commonly occurs as a complication of therapeutic thoracentesis.
• Risk factors
  • Age 20–40 years
  • Diabetes
  • Collapsed lung for > 3–7 days
  • > 1.5 L of fluid removed
  • Large associated pneumothorax
• Clinical features
  • Dyspnea, increased work of breathing
  • Cough, frothy sputum
  • Tachycardia, tachypnea, hypoxemia
• Diagnosis: confirmed by CXR or bedside ultrasound
• Treatment
  • Supplemental oxygen
  • Severe cases: NIPPV or invasive mechanical ventilation
• Prevention ^[4][28]
  • Limit pleural fluid removal to < 1.2–1.5 L at a time.
  • Avoid pleural pressures < -20 cm H₂O.

Stop therapeutic thoracentesis if patients develop chest discomfort, cough, or hypoxia, as this could represent reexpansion pulmonary edema

Indwelling pleural catheter ^{[29][30][31][32]}

• Goal: recurrent pleural fluid removal without repeated puncture
• Indication: rapidly reaccumulating pleural effusions (e.g., malignant effusions ) ^[31][32]
• Contraindications: See “Contraindications to thoracentesis.”
• Procedure ^[33]
  • A pleural catheter is inserted under the guidance of interventional radiology.
  • Similar to thoracentesis, except that the catheter is tunneled into the skin and can remain in situ for months.
• Complications ^[33][34]
  • Pain
  • Mechanical: dislodgement, blockage, leak, tube fracture
  • Infection: cellulitis, tunnel infection, empyema
  • Fibrosis and loculation within the pleural cavity
  • Catheter tract metastasis (i.e., deposition of malignant tissue at insertion site)

Mild cases of superficial cellulitis can often be treated with antibiotics without the need for catheter removal. ^[35]

Surgical procedures ^[6]

Consultation with a thoracic surgeon and/or chest physician is recommended.

Tube thoracostomy

• Indications
  • Pleural effusion in combination with significant cardiac and/or respiratory decompensation ^[36]
  • For recurrent pleural effusion or urgent drainage of infected and/or loculated effusions ^[37][38]
  • Drainage of high-viscosity fluid that is likely to clog ^[39][40]
    • Empyema
    • Hemothorax
• Procedure: See “Chest tube placement.”

Video-assisted thoracoscopic surgery (VATS)

• Definition: a minimally invasive surgical method used for diagnosis and treatment of various thoracic pathologies
• Indications
  • Collection of histological samples in malignant effusions
  • Pleural biopsy
  • Drainage of parapneumonic effusions that cannot be sufficiently controlled by tube thoracostomy
  • Drainage of pleural empyema and debridement of fibrin deposits, adhesions, and scar tissue

Pleurodesis ^[30][31]

• Definition: chemical or surgical obliteration of the pleural space
• Indication
  • Recurrent malignant effusions ^[32]
  • Effusions that do not respond to drugs (e.g., diuretics, antibiotics)
• Contraindications ^[29]
  • Predicted survival < 3 months
  • Trapped lung
• Procedure
  • After draining the pleural effusion, a substance (e.g., talc) is introduced into the pleural cavity.
  • This induces an inflammatory reaction that causes the pleural layers to bind together.
  • Alternatively, thoracoscopic pleurodesis with partial resection of the pleural layers may be performed.
• Complication: fibrothorax

A chest x-ray should be performed after each of these procedures to rule out iatrogenic pneumothorax

Pleural fluid analysis is necessary in almost all cases to distinguish between the various subtypes of pleural effusion. Treatment depends on the underlying cause. Subtypes of pleural effusion include the following:

• Parapneumonic effusion
• Pleural empyema
• Nontraumatic hemothorax
• Malignant pleural effusion
• Chylothorax
• Pseudochylothorax

Definition ^[3][41]

• Accumulation of exudative fluid in the pleural cavity in response to pneumonia
  • Uncomplicated: without direct bacterial invasion
  • Complicated: extension of bacterial infection into the pleural space

Distinguishing features ^{[4][11][15][41]}

• Clinical features
  • Fever, chills
  • Cough
  • Chest discomfort
• Diagnostics
  • Imaging: associated pneumonia
  • Pleural fluid analysis
    • Exudative effusion
    • Cloudy or purulent appearance
    • WBC count > 10,000 cells/μL
    • Positive Gram stain/culture for complicated parapneumonic effusion
  • Pleural fluid criteria for complicated parapneumonic effusion
    • pH < 7.2
    • ↑ LDH
    • Glucose < 60 mg/dL (< 3.3 mmol/L)

Treatment ^{[11][38][42][43][44]}

• All patients: systemic antibiotic treatment
  • Early antibiotic treatment can prevent progression to complicated effusion and empyema.
  • See “Pneumonia treatment” for empiric antibiotic regimens.
• Patients with complicated parapneumonic effusions: therapeutic thoracentesis
• Complicated parapneumonic effusions at high risk of progression to pleural empyema: Consult surgery for surgical drainage. ^[21]

Definition ^[41]

• Accumulation of pus in the pleural cavity

Etiology ^[15][41]

• Most common: pneumonia
• Less common
  • Infected hemothorax
  • Ruptured lung abscess
  • Esophageal tear
  • Thoracic trauma

Classification ^[45][46]

• Stage I (exudative): accumulation of fluid and pus
• Stage II (fibrinopurulent): aggregation of fibrin deposits that form septations and pockets
• Stage III (organizing): formation of thick fibrous peel on pleural surface that restricts lung movement

Distinguishing features ^[41]

• Clinical features
  • Fever, chills
  • Cough
  • Chest discomfort
• Diagnostics
  • CXR: will typically show opacity with one or more of the following characteristics ^[47]
    • Meniscus sign
    • Lenticular shape
    • Diffuse consolidation of adjacent lung
  • Ultrasound: heterogeneous fluid collection
  • Chest CT ; ^[10]
    • Distinctive appearance of empyema fluid
    • Split pleura sign: thickening of visceral and parietal pleura caused by fibrin that adheres to the surfaces, resulting in vascular proliferation
    • Septations
    • Displacement and compression of the adjacent lung
  • Pleural fluid analysis
    • Exudative effusion
    • Grossly purulent appearance
    • Positive Gram stain and bacterial culture
    • pH < 7.2
    • Low glucose (< 30–60 mg/dL)

Treatment of pleural empyema

Empiric antibiotic therapy for pleural infection ^{[38][42][43][44]}

All patients should receive empiric antibiotics adjusted to their needs, local resistance patterns, and institutional guidelines.

• Community-acquired pleural empyema ^[45]
  • Combination therapy with a parenteral second- or third-generation cephalosporin (e.g., ceftriaxone ) PLUS one of the following for anaerobic coverage:
    • Metronidazole
    • Clindamycin
  • Or single-agent therapy with a parenteral aminopenicillin and β-lactamase inhibitor (e.g., ampicillin-sulbactam )
• Hospital-acquired pleural empyema: Add MRSA and pseudomonal coverage to the above. ^[45]
  • Vancomycin PLUS one of the following:
    • Cefepime and metronidazole
    • Piperacillin-tazobactam
    • Meropenem (if extended-spectrum β-lactamase-producing organisms are suspected)
• Additional considerations ^[45]
  • Aminoglycoside antibiotics are not recommended because of poor pleural bioavailability.
  • Use empyema fluid culture to guide therapy.
  • Intrapleural antibiotics are not recommended.
  • Drainage should be arranged as quickly as possible for source control.
  • Duration of therapy depends on the identified organism, source control, and clinical response.
  • See tuberculosis therapy for the treatment of suspected tuberculous effusion.

Definitive treatment ^[45]

• Stage I
  • Chest tube (thoracostomy) to remove empyema fluid
  • Consider intrapleural administration of fibrinolytic agents.
• Stage II or mixed stage II/III
  • First-line: chest tube drainage
  • Second-line: VATS debridement if chest-tube drainage is ineffective
• Stage III
  • VATS debridement
  • Pleurectomy and lung decortication via open thoracotomy

Definition ^[48][49]

• Spontaneous or nontraumatic accumulation of blood in the pleural cavity

Etiology ^[49]

• Most common: spontaneous pneumothorax
• Less common
  • Vascular disease
  • Malignancy
  • Coagulation disorders
  • Necrotizing pneumonia ^[50]
  • Endometriosis
  • Bony exostoses
• See ”Penetrating trauma” for traumatic causes.

Distinguishing features

• Clinical
  • Symptoms of an underlying disorder
  • If there is significant blood loss: hypotension, tachycardia
• Diagnostics
  • CXR: can show associated pneumothorax or malignancy
  • Ultrasound: heterogeneous fluid collection
  • Chest CT: hyperattenuating fluid collection; can reveal an underlying malignancy
  • Chest CTA: allows for the identification of the source of hemorrhage (e.g., vascular abnormalities)
  • Pleural fluid analysis
    • Bloody appearance
    • RBC count > 5000 cells/mcL
    • Hematocrit > 0.5 × peripheral hematocrit
  • Laboratory studies: ↓ hemoglobin

Treatment of nontraumatic hemothorax ^[48][49]

• Stabilize the patient.
  • Fluid resuscitation and blood transfusions as needed (see “Massive transfusion protocol”)
  • Anticoagulant reversal (if applicable)
  • Chest tube insertion indicated for most patients
  • Urgent thoracotomy indicated for massive hemothorax (rare)
• Identify and treat the underlying cause.
• Consult surgery or interventional radiology for bleeding from tumors or vascular pathology.

A hemothorax, however small, must always be drained because blood in the pleural cavity will clot if not evacuated, resulting in a trapped lung or an empyema.

Use caution when inserting a chest tube if clinical and radiological signs suggest hemothorax secondary to aortic dissection or injury, as this may accelerate blood loss. ^[18]

Description ^[51]

• Definition: accumulation of exudative fluid and malignant cells in the pleural cavity
• Pathophysiology: cancer-related barrier dysfunction of the capillary walls → increased permeation of plasma protein, blood cells, and tumor cells

Etiology ^[51]

• Caused by either direct invasion of the pleural space or distant metastases
  • Most common: lung cancer, breast cancer
  • Less common: mesothelioma, lymphoma, and pleural metastases

Distinguishing features ^[51]

• Clinical: symptoms of underlying malignancy (e.g., constitutional symptoms, cachexia, hemoptysis)
• Diagnostics
  • Imaging: associated underlying malignancy
  • Pleural fluid analysis
    • Cell-rich exudative effusion
    • Cloudy or straw-colored appearance
    • Abnormal cytology
      • Pronounced nucleoli
      • Cells with multiple nuclei
      • Numerous figures of mitosis
    • pH < 7.2
    • Glucose < 60 mg/dL
    • Amylase > 200 mcg/dL
    • LDH usually high (> 0.45 x normal serum LDH)
    • If hemorrhagic: bloody appearance, RBC count > 5,000 cells/μL
  • Laboratory studies: positive tumor markers

Treatment ^[52]

• Asymptomatic: supportive care
• Symptomatic
  • Therapeutic thoracentesis
  • Indwelling pleural catheter
  • Chemical pleurodesis
• Treatment of underlying malignancy as needed

Definition ^[7]

• Accumulation of lymphatic fluid from the thoracic duct (chyle) in the pleural cavity

Etiology ^[7]

• Trauma (including iatrogenic)
• Malignancy (e.g., lymphoma, bronchogenic carcinoma)
• Congenital lymphatic anomalies (e.g., lymphangiectasis)

Distinguishing features ^[7]

• Clinical: Chest pain is rare.
• Diagnostics ^[2]
  • Chest CT: underlying malignancy or thoracic injury
  • Lymphangiography: source of chyle leak or obstruction
  • Pleural fluid analysis
    • Cloudy, milky fluid with high concentrations of lipids (triglycerides, cholesterol, chylomicrons, and fat-soluble vitamins)
    • Exudative effusion
    • Total cholesterol usually < 200 mg/dL
    • Triglyceride concentration > 110 mg/dL
    • LDH usually low
    • Glucose level similar to the plasma glucose level
    • Lymphocyte predominance

Treatment of chylothorax ^[53]

• First-line conservative treatment of chylothorax
  • Total parenteral nutrition and special diet
  • Adjunctive medication: somatostatin and octreotide
  • Therapeutic thoracentesis as needed based on symptoms and the patient's functional needs
  • Treatment of underlying disorder
• Surgical treatment: via thoracotomy, thoracoscopy, or VATS
  • Indications
    • Unsuccessful conservative treatment
    • Clinical deterioration (e.g., nutritional or metabolic)
    • Chyle drainage
      • > 1000–1500 mL/day
      • Up to 1000 mL/day for ≥ 5 days
      • Unchanged over 1–2 weeks
    • Persistent chyle leak: > 100 mL/day for > 2 weeks
  • Procedures
    • Thoracic duct: leak repair or ligation
    • Pleura: defect repair, pleurodesis, or pleurectomy
    • Diversion of chyle into a vein, the peritoneum, or externally
• Interventional radiology
  • Indications: an alternative for patients who cannot tolerate operative procedures and for whom the treatment is anatomically feasible
  • Procedures
    • TIPS procedure (for hepatic chylothorax)
    • Embolization or disruption of the lymph ducts
    • Percutaneous repair of the thoracic ducts

Definition ^[7][54]

• Accumulation of cholesterol-rich fluid due to chronic inflammation in the pleural cavity

Etiology ^[7][54]

• Chronic pleural inflammation (e.g., due to underlying rheumatoid arthritis, pulmonary tuberculosis)

Distinguishing features ^[7][54]

• Clinical
  • Chronic symptoms of underlying disorder
  • Dyspnea and chest pain in ∼ 75% of patients ^[54]
• Diagnostics
  • Imaging: signs of underlying disorder
  • Pleural fluid analysis
    • Cloudy, milky appearance
    • Exudative effusion
    • Total cholesterol usually > 200 mg/dL
    • Triglyceride concentration < 110 mg/dL
    • Presence of cholesterol crystals

In contrast to chylothorax, a pseudochylothorax is characterized by high cholesterol and low triglyceride levels in the pleural fluid. The presence of cholesterol crystals may also help to differentiate a pseudochylothorax from a chylothorax.

Treatment

• Identical to first-line conservative treatment of chylothorax ^[54]

Etiology ^[55][56]

• Viral infections
  • Most common cause
  • Adenovirus, coxsackieviruses, CMV, EBV, influenza virus, parainfluenza virus, RSV
• Bacterial infections
  • Pneumonia (parapneumonic pleuritis)
  • Tuberculosis (TB pleuritis)
• Inflammatory conditions
  • Systemic lupus erythematosus
  • Rheumatoid arthritis
  • Sjogren syndrome
• Pulmonary conditions
  • Pneumothorax
  • Asbestosis
  • Malignancy e.g., mesothelioma
  • Pulmonary embolism
• Cardiac conditions
  • Myocardial infarction
  • Aortic dissection
  • Cardiac surgery
• Drugs
  • Amiodarone, bleomycin, methotrexate
  • Isoniazid, procainamide, hydralazine

Clinical features

• Pleuritic chest pain
• Pleural friction rub
• Further symptoms depend on the underlying disease, e.g.:
  • Dry cough
  • Dyspnea
  • Constitutional symptoms

Diagnosis ^[57]

• History and physical examination
• Chest x-ray: signs of underlying pulmonary pathology e.g., pneumonia, pleural effusion
• Further investigation to rule out differential diagnoses; e.g., ECG to assess for signs of MI or pericarditis

Rule out life-threatening causes of pleuritic chest pain such as pulmonary embolism, myocardial infarction, and pneumothorax before making a clinical diagnosis of pleurisy.

Differential diagnosis of pleuritic chest pain ^[57]

• Myocardial infarction
• Pulmonary embolism
• Pneumothorax
• Pericarditis
• Bornholm disease

Treatment ^[55]

• Analgesia: NSAIDs (first line) can be used for relief of symptoms
• Treat underlying cause accordingly.