19 - Pleural and Mediastinal Pathology Flashcards
What is a pleural effusion?
Accumulation of fluid (>15 ml) in the pleural space secondary to:
- increase in hydrostatic pressure: transudate (ie CHF, lymphatic blockage from tumor)
- decreased osmostic pressure: transudate (ie nephrotic syndrome, cirrhosis, malnutrition)
- increased vascular permeability: exudate (ie from pneumonia)
What is the difference between transudate and exudate?
Transudate: extravascular fluid that has low levels of protein, low specific gravity, and low cellularity. Due to increased hydrostatic pressure or decreased oncotic pressure.
Exudate: extravascular fluid that has high protein, high specific gravity, and increased cellularity. Due to increased vascular permeability.
What is the clinical presentation of someone with a pleural effusion?
Dyspnea, pleuritic pain, cough
Enlarged hemithorax: dullness on percussion, decreased or absent breath sounds
Compression of hte lung: atalectasis leading to resp distress
What is the clinical management of a pleural effusion?
- CXR
- Thoracentesis (needle is inserted into the pleural space between the lungs and the chest wall. This procedure is done to remove excess fluid - Dr. google)
- Analysis of pleural fluid: chemistry, culture, cytology
- Pleural biopsy
- Treatment of underlying cause
What are the five common causes of pleural effusion?
- Infections: bacterial, viral, TB.
- PE
- Malignant neoplasms
- Trauma
- Systemic conditions: CHF, cirrhosis, nephrotic syndrome, collagen vascular disease.
What are three examples of inflammatory pleural effusions?
- Serofibrinous (serum and fibrin)
- Suppurative (pus/empyema)
- Hemorrhagic
What are three examples of non-inflammatory pleural effusions?
- Hydrothorax
- Hemothorax
- Chylothorax
What are the causes of the three types of inflammatory pleual effusions?
Serofibrinous (serum and fibrin): pneumonia, TB, lung infarcts, abscesses
Suppurative (pus/empyema): infection
Hemorrhagic: coagulopathies, rickettsial disease, malignant neoplasms
What is empyema (pyothorax)? What is the treatment of choice?
Purulent pleural effusions complicating lung infections (pneumococci, staphilococi, and streptococci)
Aka “supprative pleuritis”
Pleural surface coated by shaggy, thick fibrin layer mixed with greenish purulent exudate. This limits lung expansion.
Surgical decortication is treatment of choice.
What are the causes of the three types of non-inflammatory effusions?
Hydrothorax: card failure, pulmonary congestion, cirrhosis, urenia, renal failure
Hemothorax: ruptured aortic aneurysm, trauma
Chylothorax: thoracic duct trauma or lumphatic ollucion secondary to malignancy
What is a pneumothorax? What is it most commonly assocaited with?
Presence of air or gas within the pleural cavity.
Can be spontaneous, traumatic, or therapeutic.
Most commonly associated with emphysema, asthma, and TB.
Who gets spontaneous idiopathic pneumothorax? What causes it?
Encountered in yoing people secondary to rupture of small apical lung blebs.
The trachea often deviates to the ipsilateral side.
Usually subsides spontaneously.
What is a tension pneumothorax?
When the defect acts as a flap that permits entrance of air during inspiration but doesn’t allow escape of air during espiration.
What is the mechanism of a pneumothroax?
Perforation of the visceral pleura and entry of air from the lung.
Penetration of air from the chest wall, diaphragm, mediastinum or esophagus.
Gas-forming organisms in emphyema.
What are clinical sypmtoms seen with pleural effusion?
- Chest pain, dyspnea.
- Absent breath sounds on ascultation
- Tympanitic percussion (hyper-resonance)
- Contralateral deviation of the trachea on CXR
- Compression and collapse of lung parenchyma with atelectasis
- Marked respiratory distress
What are some (4) causes of spontaneous pneumothorax?
May be idiopathic (unknown cause)
Secondary to rupture of pleural blel or bulla (large air-filled sacs that can rupture)
Bronchopleural fistula
Bullous emphysema
What causes a tension pneumothorax and how does the mediastinum change in response?
Penetrating trauma that produces increased pleural cavity pressure with compression and atalectasis.
Flap allows air in but not out.
Sudden onset of respiratory distress (medical emergency)
Tracheal deviation to CONTRA side of pneumothorax.
What are the two types of pleural neoplasms?
Benign: solitary fibrous tumor (pleural fibroma)
Malignant: mets from other organs or malignant mesothelioma.
What is a solitary fibrous tumor? What are symptoms? How is it treated?
Soft tissue (mesenchymal) tumor; Polypoid, well-circumscribed, pedunculated.
Composed of fibroblasts with abundant collagenized stroma; spindle cells.
- Benign tumor cured with simple excision.
- Usually incidental discovery.
- Associated with hypoglycemia nad clubbing.
What is malignant mesothelioma? What age group is affected?
Neoplastic proliferation of mesothelial cells lining serosal surfaces.
Affects 15-20 people/million/year
Most commonly in adults over 50.
What is the etiology of malignant mesothelioma?
- Asbestos
- Radiation
- Chronic inflammation
- Viral infections (SV40 simian virus in old polio vaccines)
- Idiopathic (up to 50% cases)
Who gets asbestos-related mesothelioma?
People in coastal areas of the US and GB and mining areas in Canada and south africa.
Lifetime risk for getting mesothelioma is up to 10% in pts with history of heavy exposure.
Long latency period of 20-40 yrs.
Occupational exposure: millworkers, roofing materials, textiles, insulation, shipyard workers.
What are clinical symptoms of malignant mesothelioma?
Insidious, slow growing neoplasm.
Recurrent lpeural effusions.
Chest pain and duyspnea in advanced stages. Only 20% of pts hace pulmonary fibrosis (asbestosis)
Fatal malignancy: median survival time is 18 months.
How does malignant mesothelioma spread?
Along mesothelial surfaces.
Compoased of bland-appearaing cuboidal cells that resemble normal mesorhelial cells (well-differntiated)
Very difficult to distinguish from metastatic carcinoma to the pleura.
Can also involve other pleura.
