Pleural & Mediastinal Pathology

Question 1

What types of cells are in pleural membranes?

Answer 1

normally flat cuboidal epithelia

Question 2

What is the definition of pleural effusion?

Answer 2

Accumulation of fluid (>15mL) in the pleural space secondary to: Increase in hydrostatic pressure, Decreased osmotic pressure & Increased vascular permeability

Question 3

How does pleural effusion manifest clinically?

Answer 3

• Dyspnea, pleuritic pain, cough
• Enlarged hemithorax: dullness on percussion & decreased or absent breath sounds
• Compression of the lung: atelectasis leading to respiratory distress

Question 4

How do you diagnose and treat pleural effusion?

Answer 4

Dx: Chest X-ray, Thoracentesis, Analysis of pleural fluid or Pleural biopsy (percutaneous, open)

Tx underlying cause

Question 5

What are common causes of pleural effusions?

Answer 5

• Infections
• Pulmonary embolism
• Malignant neoplasms
• Trauma
• Systemic conditions

Question 6

What are the inflammatory pleural effusions?

Answer 6

• Serofibrinous
• Suppurative (empyema)
• Hemorrhagic

Question 7

What are the non-inflammatory pleural effusion?

Answer 7

• Hydrothorax
• Hemothorax
• Chylothorax

Question 8

What causes Serous, fibrinous and serofibrinous pleural effusions?

Answer 8

inflammatory conditions such as pneumonia, T.B., lung infarcts, abscesses

Question 9

What causes empyema?

Answer 9

localized accumulation of pus due to organisms

Question 10

What causes hemorrhagic pleuritis?

Answer 10

coagulopathies, rickettsial disease, malignant neoplasms

Question 11

How does empyema look?

Answer 11

Pleural surface is coated by shaggy thick fibrin layer admixed with greenish purulent exudate and organization produces adhesions and loculation circumscribing the pus and limiting lung expansion

Question 12

How do you treat empyema?

Answer 12

Surgical decortication is treatment of choice

Question 13

What is hydrothorax?

Answer 13

clear serous fluid (cardiac failure, pulmonary congestion

and edema, cirrhosis, uremia, renal failure)

Question 14

What is a hemothorax?

Answer 14

hemorrhagic fluid (ruptured aortic aneurysm, trauma)

Question 15

What is a chylothorax?

Answer 15

milky fluid from lymph (thoracic duct trauma or lymphatics occlusion secondary to malignancy)

Question 16

What is a pneumothorax?

Answer 16

Presence of air or gas within the pleural cavity can be spontaneous, traumatic or therapeutic

commonly associated with emphysema, asthma and tuberculosis

Question 17

What is Spontaneous idiopathic pneumothorax?

Answer 17

young individuals secondary to rupture of small apical lung blebs – the trachea is deviated to the ipsilateral side – usually subsides spontaneously

Question 18

What is Tension pneumothorax?

Answer 18

defect acts as a flap that permits entrance of air during inspiration but does not allow escape of air during expiration

Question 19

What are general mechanisms of pneumothorax?

Answer 19

• 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 empyema

Question 20

What are the symptoms of pneumothorax?

Answer 20

• Chest pain, dyspnea
• Absent breath sounds on auscultation
• Tympanitic percussion (hyper-resonance)
• Contralateral deviation of the trachea on CXR
• Compression and collapse of lung parenchyma with atelectasis
• Marked respiratory distress

Question 21

What can cause tension pneumothorax?

Answer 21

Due to penetrating trauma to the lungs

Question 22

What is Solitary Fibrous Tumor?

Answer 22

• Polypoid, well-circumscribed, pedunculated
• Composed of fibroblasts with abundant collagenized stroma
• Benign tumor, cured by simple excision

Question 23

What are the symptoms of Solitary Fibrous Tumor?

Answer 23

Mostly asymptomatic and discovered incidentally on chest X-rays

Associated with hypoglycemia and clubbing of the fingers

Question 24

What is malignant mesothelioma?

Answer 24

Neoplastic proliferation of mesothelial cells lining serosal surfaces

Question 25

what is the distribution of mesothelioma?

Answer 25

Affects 15-20 persons per million/per year in the general population Most common in adults over 50

Question 26

What can cause mesothelioma?

Answer 26

* Asbestos exposure * Radiation * Chronic inflammation * Viral infections (SV40 simian virus in old polio vaccines) * Idiopathic (up to 50% of cases)

Question 27

* Lifetime risk for developing mesothelioma is up to 10% in patients with a history of heavy exposure * Long latency period (20-40 years) * Occupational exposure: millworkers, roofing materials, textiles, insulation, shipyard workers Is characteristic of what?

Answer 27

Asbestos-related Mesothelioma

Question 28

What are the symptoms of Asbestos-related Mesothelioma?

Answer 28

* Insidious, slow growing neoplasm * Recurrent pleural effusions * Chest pain and dyspnea in more advanced stages * Only 20% of patients have pulmonary fibrosis * Fatal malignancy; median survival 18 months

Question 29

What happens pathologically in mesothelioma?

Answer 29

Tumor characteristically spreads along mesothelial surfaces composed of bland-appearing cuboidal cells spares parenchyma

Question 30

Metastatic tumors are more common than primary malignancies in the pleura, where do they usually come from?

Answer 30

Lung is the most frequent source of metastases to the pleura; other tumors include breast and ovarian cancer, pancreas, kidney and spread is by blood, lymphatics or direct extension

Question 31

What is acute mediastinitis?

Answer 31

Complication of conditions affecting neighboring organs; i.e., esophageal perforation, perforation of lung abscess, sternal osteomyelitis

Question 32

What is granulomatous mediastinitis?

Answer 32

Chronic disorder secondary to fungal or mycobacterial infection

Question 33

What organisms can cause Granulomatous mediastinitis?

Answer 33

* Histoplasmosis * Tuberculosis * Cryptococcosis * Atypical mycobacteria * Aspergillosis

Question 34

What are congenital cysts?

Answer 34

* Usually unilocular * Children aged 5 to 15 years * Lined by simple cuboidal epithelium * May be filled with serous fluid

Question 35

What is Thymic Hyperplasia?

Answer 35

Thymic lymphoid follicular hyperplasia: associated with myasthenia gravis and other autoimmune disorders

Question 36

* Neoplastic proliferation of thymic epithelial cells * Usually contains abundant immature T-lymphocytes * Frequently associated with myasthenia gravis and other paraneoplastic syndromes * May be composed of spindle cells or round epithelioid cells * Slow-growing tumor that may recur but rarely metastasizes Are characteristics of what?

Answer 36

thymoma

Question 37

What are the symptoms of thymoma?

Answer 37

* Asymptomatic in 30% of patients * Cough, dyspnea, chest pain * Superior vena cava syndrome * Paraneoplastic syndromes

Question 38

What Paraneoplastic syndromes are associated with thymoma?

Answer 38

- Myasthenia gravis - Pure red cell aplasia - Hypogammaglobulinemia - Agranulocytosis; white blood cell aplasia - Polymyositis; SLE - Pemphigus vulgaris, disseminated herpes

Question 39

What is prognosis for thymoma?

Answer 39

• Depends on the status of the capsule – Encapsulated tumors are cured by complete surgical excision and Invasive tumors tend to recur repeatedly and may eventually metastasize • Recurrent tumors may progress to thymic carcinoma

Question 40

What is the histology of thymic carcinoma?

Answer 40

• Resemble other types of carcinoma occurring in other organs (squamous, small cell, adenocarcinoma, etc) • Diagnosis of exclusion (i.e., there are no specific features that permit definite histologic diagnosis)