Pleural and Mediastinal Pathology Flashcards
1
Q
What can lead to a pleural effusion?
A
Accumulation of fluid (>15mL) in the pleural space secondary to:
-
Increase in hydrostatic pressure
- congestive heart failure, lymphatic blockage due to tumor
-
Decreased osmotic pressure
- nephrotic syndrome
-
Increased vascular permeability
- pneumonia
2
Q
How does a pleural effusion clinically manifest?
A
- Dyspnea, pleuritic pain, cough
-
Enlarged hemithorax
- dullness on percussion
- decreased or absent breath sounds
-
Compression of the lung
- atelectasis leading to respiratory distress
3
Q
How is a pleural effusion diagnosed and treated?
A
- Chest X-ray
- Thoracentesis
- Analysis of pleural fluid
- Chemistry
- Culture
- Cytology
- Pleural biopsy (percutaneous, open)
- Treatment of underlying cause
4
Q
Common Causes of Pleural Effusion:
A
-
Infections
- Bacterial pneumonia
- Viral disease
- Tuberculosis
- Pulmonary embolism
- Malignant neoplasms
- Trauma
-
Systemic conditions
- Congestive heart failure
- Cirrhosis
- Nephrotic syndrome
- Collagen vascular diseases
5
Q
List the different types of pleural effusions:
A
-
Inflammatory Pleural Effusions:
- Serofibrinous
- Suppurative (empyema)
- Hemorrhagic
-
Non-Inflammatory Pleural Effusions:
- Hydrothorax
- Hemothorax
- Chylothorax
6
Q
What are causes of inflammatory pleural effusions?
A
- Serous, fibrinous and serofibrinous: inflammatory conditions such as pneumonia, T.B., lung infarcts, abscesses
- Purulent exudate (empyema): localized accumulation of pus due to organisms
- Hemorrhagic pleuritis: coagulopathies, rickettsial disease, malignant neoplasms
7
Q
- What is an empyema (pylothorax)?
- What is done to treat it?
A
-
Purulent pleural effusions complicating lung infections
- pneumococci, staphilococci and streptococci
- A.k.a. “suppurative pleuritis”
- Pleural surface is coated by shaggy thick fibrin layer admixed with greenish purulent exudate
- Organization produces adhesions and loculation circumscribing the pus and limiting lung expansion
- Surgical decortication is treatment of choice
8
Q
What are the differences between the non-inflammatory pleural effusions?
A
-
Hydrothorax: clear serous fluid
- cardiac failure, pulmonary congestion and edema, cirrhosis, uremia, renal failure
-
Hemothorax: hemorrhagic fluid
- ruptured aortic aneurysm, trauma
-
Chylothorax: milky fluid
- thoracic duct trauma or lymphatics occlusion secondary to malignancy
9
Q
- What is a pneumothorax?
- What is it most commonly associated with?
- What are the two types of pneumothorax?
A
-
Presence of air or gas within the pleural cavity
- Spontaneous – traumatic – therapeutic
- Most commonly associated with emphysema, asthma and tuberculosis
-
Two Types:
- Spontaneous idiopathic pneumothorax
- Tension pneumothorax
10
Q
What mechanisms can form a pneumothorax?
A
- 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
11
Q
Pneumothorax
Clinical Symptoms
A
- 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
12
Q
What are the clinical signs and causes of a spontaneous pneumothorax?
A
- Encountered in young individuals secondary to rupture of small apical lung blebs or bullas
-
Trachea is deviated to the ipsilateral side
- usually subsides spontaneously
-
Causes:
- Idiopathic (unknown cause)
- Bronchopleural fistula
- Bullous emphysema
13
Q
What are the clinical signs and causes of a tension pneumothorax?
A
-
Due to penetrating trauma to the lungs
- Produces increased pleural cavity pressure with compression and atelectasis
- Flap-like pleural defect acts like a valve allowing air in but not out
- Sudden onset of respiratory distress (medical emergency)
- Trachea deviated to contralateral side of pneumothorax
14
Q
Example of Pleural Neoplasms:
- Benign:
- Malignant:
A
- Benign:
- Solitary fibrous tumor (pleural fibroma)
- Malignant:
- Metastases from other organs
- Malignant mesothelioma
15
Q
- Describe a solitary fibrous tumor:
- What is it associated with?
A
- Polypoid, well-circumscribed, pedunculated
- Composed of fibroblasts with abundant collagenized stroma
- Benign tumor, cured by simple excision
- Mostly asymptomatic and discovered incidentally on chest X-rays
- Associated with hypoglycemia and clubbing of the fingers
16
Q
- Define malignant mesothelioma:
- What age group is it most common in?
A
- Neoplastic proliferation of mesothelial cells lining serosal surfaces
- Affects 15-20 persons per million/per year in the general population
- Most common in adults over 50
17
Q
What are etiologies of malignant mesothelioma?
A
- Asbestos exposure
- Idiopathic (up to 50% of cases)
- Radiation
- Chronic inflammation
- Viral infections (SV40 simian virus in old polio vaccines)
18
Q
What is the incidence of asbestos-related mesothelioma?
A
- Epidemiologic studies (coastal areas of US and GB and mining areas in Canada and So. Africa)
- 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
19
Q
Abestos-related Mesothelioma:
Clinical Symptoms
A
- Insidious, slow growing neoplasm
- Recurrent pleural effusions
- Chest pain and dyspnea in more advanced stages
- Only 20% of patients have pulmonary fibrosis (asbestosis)
- Fatal malignancy; median survival 18 months
20
Q
How does mesothelioma appear histologically?
A
- Tumor characteristically spreads along mesothelial surfaces
- Composed of bland-appearing cuboidal cells that resemble normal mesothelial cells (well-differentiated neoplasm)
- Very difficult for pathologist to distinguish mesothelioma from metastatic carcinoma to the pleura
- Can also involve other serosal surfaces like peritoneum, tunica vaginalis and pericardium
21
Q
________ ______ are more common than primary malignancies in the pleura
A
Metastatic tumors are more common than primary malignancies in the pleura
22
Q
Describe how metastatic tumors spread:
A
-
Lung is the most frequent source of metastases to the pleura
- other tumors include breast and ovarian cancer, pancreas, kidney
- Spread is by blood, lymphatics or direct extension
- Metastases are often multiple and bilateral
23
Q
What are the mediastinal compartments?
A
- anterior/superior
- medial
- posterior
24
Q
What are the different types of mediastinal inflammation?
A
-
Acute mediastinitis
- Complication of conditions affecting neighboring organs
- esophageal perforation, perforation of lung abscess, sternal osteomyelitis, etc
-
Granulomatous mediastinitis
- Chronic disorder secondary to fungal or mycobacterial infection
-
Idiopathic sclerosing mediastinitis
- Unknown etiology
25
Q
What causes granulomatous mediastinitis?
A
- Histoplasmosis
- Tuberculosis
- Cryptococcosis
- Atypical mycobacteria
- Aspergillosis
26
Q
Tumors of the Mediastinum
Anterior/Superior
A
- Metastatic tumors
- Thymoma, thymic CA
- Lymphomas
- Germ cell tumors
- Sarcomas
- Congenital thymic cysts
27
Q
Tumors of the Mediastinum
Medial
A
- Metastatic tumors
- Pericardial cyst
- Bronchogenic cyst
- Lymphomas
28
Q
Tumors of the Mediastinum
Posterior
A
Neurogenic tumors
- Schwannoma
- Neurofibroma
- Ganglioneuroma
- Neuroblastoma
29
Q
Congenital Cysts
- Clinical Presentation:
A
- Usually unilocular
- Children aged 5 to 15 years
- Lined by simple cuboidal epithelium
- May be filled with serous fluid
30
Q
What is thymic lymphoid follicular hyperplasia associated with?
A
myasthenia gravis and other autoimmune disorders
31
Q
Myasthenia Gravis
- Associated with:
- Pathogenesis:
- Symptoms:
A
- May be associated with thymic lesions –
- Thymic hyperplasia
- Thymoma (30-40% of patients with thymoma develop MG)
- Thymic carcinoma
-
Auto-antibodies form to acetylcholine receptor in neuromuscular junction
- Autosensitization to AChR is initiated in the thymus due to defective confrontation of ACh-secreting thymic myoid cells with T-lymphocytes
- Symptoms: weakness, fatigability, ptosis, diplopia
32
Q
What is a thymoma?
- What is its clinical presentation?
- How does it appear histologically?
A
-
Neoplastic proliferation of thymic epithelial cells
- Usually contains abundant immature T-lymphocytes (non-neoplastic)
- Frequently associated with myasthenia gravis and other paraneoplastic syndromes
- May be composed of spindle cells or round epithelioid cells
- type A (spindle cells)
- type B (round cells)
- type AB (mixture of both)
- Slow-growing tumor that may recur but rarely metastasizes
33
Q
Thymoma
- Symptoms:
- Paraneoplastic syndromes:
A
- Symptoms:
- Asymptomatic in 30% of patients
- Cough, dyspnea, chest pain
-
Superior vena cava syndrome
- obscures or obstructs the SVC
- Paraneoplastic syndromes:
- Myasthenia gravis
- Pure red cell aplasia
- Hypogammaglobulinemia
- Agranulocytosis; white blood cell aplasia
- Polymyositis; SLE
- Pemphigus vulgaris, disseminated herpes
34
Q
What is the clinical behavior of a thymoma?
A
- Depends on the status of the capsule
- Encapsulated tumors ⇒ cured by complete surgical excision
- Invasive tumors ⇒ tend to recur repeatedly and may eventually metastasize
- Recurrent tumors may progress to thymic carcinoma
35
Q
- What is the histology of thymic carcinoma?
- How is a diagnosis made?
A
- 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)
