Emphysema

Emphysema

Definition

It is the permanent dilatation of air spaces and destruction of their wall distal to terminal bronchiole.

Classification of emphysema

1. Centriacinar/ centrilobular/ proximal part emphysema.

2. Panacinar/ panlobular/ entire respiratory acinus emphysema.

Involvement of the anatomical part of the lungs

3. Paraseptal/ distal acinar emphysema.

4. Irregular/ para-cicatricial emphysema.

5. Mixed/ unclassified emphysema.

Etiopathogenesis

1. Tobacco smoking.

2. Decrease level of alpha-1 antitrypsin.

3. Atmospheric pollution.

4. Occupational exposure.

5. Genetic factor.

Protease anti-protease mechanism

Morphological changes

Grossly : 

1. Lung will be voluminous and pale with blood.
2. The edges of the lungs are rounded.
3. Mild cases shows dilatation of air spaces.
4. Advanced cases shows subpleural bullae and blebs.

Bullae - these are air filled cyst-like or bubble like structures, larger than 1 cm in diameter. They are formed by rupture of adjacent air spaces. 

Blebs - it is the result of rupture of alveoli directly into the subpleural interstitial tissue. these are the most common cause of spontaneous pneumothorax. 

Microscopically : Depending upon the type of emphysema -
1. Dilatation of  air spaces and destruction of septal walls of part of acinus involved respiratory bronchioles, alveolar ducts and alveolar sacs.
2. Changes of bronchitis may be present.
3. Bullae and blebs when present show fibrosis and chronic inflammation of the walls.


 Clinical Features : Features may develop after degeneration of 33% of lung parenchyma. Usually diagnosing age is 60 years. Thus clinical features of chronic bronchitis and emphysema are same that is-
i. There is long history of slowly increasing severe exertional dyspnoea.
ii. Patient take help always to accessory muscles for respiration.
iii. Chest is barrel-shaped and hyper-resonant.
iv. Cough occurs late after dyspnoea starts and is associated with scanty mucoid sputum.
v. Recurrent respiratory infections are not frequent.
vi. Patient are called 'pink puffers' as they remain well oxygenated and have tachypnoea.
vii. Weight loss is common.
viii. Cor pulmonale (right side enlargement of the heart).
ix. Hypercapneic respiratory failure.
x. Chest X-rays shows small heart with hyperinflated lungs.




                                                                  Source : Textbook of pathology ( Harsh Mohan ) 7th edition

Related Posts - 

• Emphysema
• Centriacinar Emphysema
• Panacinar Emphysema
• Para-septal Emphysema
• Irregular Emphysema
• Mixed Emphysema

Primary Atypical Pneumonia

Primary Atypical Pneumonia / Viral Pneumonia / Mycoplasmal Pneumonia / Interstitial Pneumonia

Viral pneumonia is characterised by patchy inflammatory changes, generally confined to interstitial tissue of the lungs without any alveolar exudate. Most of the cases are mild and momentary but some cases may be severe and fulminant.

Etiology : Interstitial pneumonia occasionally associated with psittacosis (Chlamydia) and Q fever (Coxiella). Viruses that cause viral pneumonia -

i. Respiratory Syncytial Virus (RSV) - (Most common).

ii. Mycoplasma pneumoniae.

iii. Influenza and para-influenza viruses.

iv. Adenoviruses.

v. Rhinoviruses.

vi. Coxsackieviruses.

vii. Cytomegaloviruses (CMV).

In most cases, the infection of upper respiratory tract remains such as common cold. It may be extend to lower respiratory tract and involve the interstitium of the lungs. Other conditions that may be accelerate to the viral pneumonia i.e. malnutrition, chronic debilitating diseases and alcoholism.

MORPHOLOGICAL FEATURES :

Grossly : Depending upon the severity of infection, the involvement may be patchy to massive and widespread consolidation of one or both the lungs.

1. The lungs are heavy, congested and subcrepitant.
2. Cut surface of the lung exudes small amount of frothy or bloody fluid.
3. Sometime pleura also involve.

Histologically : Hallmark of the viral pneumonia is the interstitial nature of the inflammatory reaction.

1. Interstitial inflammation : There is thickening of the alveolar walls due to -

• Congestion.
• Oedema.
• Mono-nuclear inflammatory infiltrate includes lymphocytes, macrophages and some plasma cells.

2. Necrotising bronchiolitis : This is characterised by foci of necrosis of the bronchiolar epithelium due to - 

• Inspissated secretions in the lumina.
• Mono-nuclear infiltrate in the walls and lumina.

3. Reactive changes : The lining epithelial cells of the bronchioles and alveoli proliferate in the presence of virus and may form multi-nucleated giant cells and syncytia in the bronchiolar and alveolar walls. Sometime, viral inclusions (intranuclear or intracytoplasmic) are found specially in pneumonia that cause by cytomegalovirus.

4. Alveolar changes : In severe cases, the alveolar lumina may contain - oedema fluid, fibrin, scanty inflammatory exudate and coating of alveolar walls by pink, hyaline membrane.

Microscopic appearance of viral pneumonia

COMPLICATIONS : Most of the cases of viral pneumonia recover completely. But some complications may show -

1. Bacterial infection and it's complications.
2. Interstitial fibrosis and permanent damage ( in severe cases).

Features	Lobar Pneumonia	Lobular Pneumonia	Interstitial Pneumonia
Definition	It is an acute bacterial infection of a part of lobe or entire lobe or even two lobes of one or both the lungs.	It is the infection of terminal bronchioles that extend into the surrounding alveoli resulting in patchy consolidation of lung.	It is characterized by patchy inflammatory changes generally confined to interstitial tissue without any alveolar exudates.
Etiology	Pneumococci, Staphylococcal pneumonia.	Staphylococci, Streptococci etc.	Respiratory Syncytial Virus (RSV), Mycoplasma pneumoniae.
Morphology	Stage of congestion (1-2 days), Red hepatisation  (2-4 days), Grey hepatisation (4-8 days), Resolution (8-9 days)	Patchy consolidation with central granularity, alveolar exudate, thickened septa.	Patchy to massive and widespread consolidation of one or both the lungs.
Clinical features	Shaking, Chills, Fever, Malaise, Chest pain, Dyspnoea, Tachycardia, Tachypnoea and Cyanosis.	Shaking, Chills, Fever, Malaise, Chest pain, Dyspnoea, Tachycardia, Tachypnoea and Cyanosis, Mottled patches lung in X-rays.	Initially – Fever, Headache, Muscles pain. Later – Dry, Hacking, Cough with retrosternal burning.
Complications	Organisation, Pleural effusion, Empyema, Lung abscess, Metastatic infection.	Organisation, Pleural effusion, Lung abscess, Empyema.	Interstitial fibrosis and permanent damage.

CLINICAL FEATURES : In most of the cases of viral pneumonia initially seen upper respiratory symptoms - 

• Fever
• Headache
• Muscle-ache.

After few days - 

• Dry, Hacking, Non-productive cough with retrosternal burning appears due to tracheitis and bronchitis.
• Blood film shows neutrophilia.
• Chest X-rays shows patchy or diffuse consolidation.
• Cold agglutinin in the serum are elevated in 50% cases of mycoplasmal pneumonia and 20% cases of adenovirus infection ( absent in other forms of viral pneumonia).

Source : Textbook of pathology (Harsh Mohan) 7th edition

Related Posts -

• Pneumonia
• Lobar Pneumonia.
• Lobular Pneumonia or Bronchopneumonia.
• Interstitial Pneumonia
• Legionella Pneumonia.
• How to failed lungs defense mechanism.
• Textbook of pathology (Harsh Mohan ) 7th edition.
• 
  

Pneumonia

Pneumonias 

Definition : It is an acute inflammation of lungs parenchyma with consolidation distal to terminal bronchioles ( consisting of the respiratory bronchiole, alveolar ducts, alveolar sacs and alveoli ).It may be infective and non-infective.

Pathogenesis : Microorganism can enter into the lungs by following route after failure of defensive mechanism -
i. Inhalation of air microbes.
ii. Aspiration of the microbes from the nasopharynx or oropharynx.
iii. Haematogenous spread from a distant focus of infection such as - vector population, environmental characteristics.
iv. Direct spread from a adjoining site of infection.

Classification :
1. On the basis of anatomical regions -

• Lobar Pneumonia
• Bronchopneumonia or Lobular Pneumonia
• Interstitial Pneumonia

Features of lobar and lobular pneumonia

2. On the basis of clinical aspects -

• Community-acquire Pneumonia
• Health care-associated Pneumonia (Hospital acquired Pneumonia)
• Ventilator-associated Pneumonia

3. On the basis of etiology and pathogenesis -

• Bacterial Pneumonia (Lobar pneumonia, Lobular pneumonia, Legionella pneumonia )
• Viral Pneumonia (Primary atypical pneumonia)
• Fungal pneumonia ( Pneumocystis pneumonia, Aspergillosis, Mucormycosis, Candidiasis, Histoplasmosis, Cryptococcosis, Coccidioidomycosis, Blastomycosis)
• Non infective pneumonias ( Aspiration pneumonia, Hypostatic pneumonia, Lipid pneumonia)

Features	Lobar Pneumonia	Lobular Pneumonia	Interstitial Pneumonia
Definition	It is an acute bacterial infection of a part of lobe or entire lobe or even two lobes of one or both the lungs.	It is the infection of terminal bronchioles that extend into the surrounding alveoli resulting in patchy consolidation of lung.	It is characterized by patchy inflammatory changes generally confined to interstitial tissue without any alveolar exudates.
Etiology	Pneumococci, Staphylococcal pneumonia.	Staphylococci, Streptococci etc.	Respiratory Syncytial Virus (RSV), Mycoplasma pneumoniae.
Morphology	Stage of congestion (1-2 days), Red hepatisation  (2-4 days), Grey hepatisation (4-8 days), Resolution (8-9 days)	Patchy consolidation with central granularity, alveolar exudate, thickened septa.	Patchy to massive and widespread consolidation of one or both the lungs.
Clinical features	Shaking, Chills, Fever, Malaise, Chest pain, Dyspnoea, Tachycardia, Tachypnoea and Cyanosis.	Shaking, Chills, Fever, Malaise, Chest pain, Dyspnoea, Tachycardia, Tachypnoea and Cyanosis, Mottled patches lung in X-rays.	Initially – Fever, Headache, Muscles pain. Later – Dry, Hacking, Cough with retrosternal burning.
Complications	Organisation, Pleural effusion, Empyema, Lung abscess, Metastatic infection.	Organisation, Pleural effusion, Lung abscess, Empyema.	Interstitial fibrosis and permanent damage.

Related Post :-

• Pneumonia
• Lobar Pneumonia.
• Lobular Pneumonia or Bronchopneumonia.
• Interstitial Pneumonia
• Legionella Pneumonia.
• How to failed lungs defense mechanism.
• Textbook of pathology (Harsh Mohan ) 7th edition.

Pneumonia ( Legionella pneumonia or Legionnair's disease )

Legionella pneumonia or Legionnair's disease

It is a epidemic disease caused by gram-negative bacilli, legionella pneumophila that thrives in aquatic environment. It was first recognised in those person that attending American legion convention in Philadelphia in july 1976 and hence the name.

Etiopathogenesis : This disease is epidemic occur in summer season due to

i. Spread of organism through contaminated water or air conditioning cooling towers.

ii. Immunosuppressed person ( corticosteroid therapy, old age)

iii. Cigarette smoking

MORPHOLOGICAL FEATURES :

Grossly : 

i. Consolidation of the entire lung.

ii. Pleural effusion is frequently present.

Histologically : 

i. Intra-alveolar exudate, initially of neutrophils later composed mainly macrophages.

ii. Alveolar septa shows  foci of hyperplasia of the lining epithelium and thrombosis of vessels in the septa.

iii. Special stains shows organism in the macrophages.

Features	Lobar Pneumonia	Lobular Pneumonia	Interstitial Pneumonia
Definition	It is an acute bacterial infection of a part of lobe or entire lobe or even two lobes of one or both the lungs.	It is the infection of terminal bronchioles that extend into the surrounding alveoli resulting in patchy consolidation of lung.	It is characterized by patchy inflammatory changes generally confined to interstitial tissue without any alveolar exudates.
Etiology	Pneumococci, Staphylococcal pneumonia.	Staphylococci, Streptococci etc.	Respiratory Syncytial Virus (RSV), Mycoplasma pneumoniae.
Morphology	Stage of congestion (1-2 days), Red hepatisation  (2-4 days), Grey hepatisation (4-8 days), Resolution (8-9 days)	Patchy consolidation with central granularity, alveolar exudate, thickened septa.	Patchy to massive and widespread consolidation of one or both the lungs.
Clinical features	Shaking, Chills, Fever, Malaise, Chest pain, Dyspnoea, Tachycardia, Tachypnoea and Cyanosis.	Shaking, Chills, Fever, Malaise, Chest pain, Dyspnoea, Tachycardia, Tachypnoea and Cyanosis, Mottled patches lung in X-rays.	Initially – Fever, Headache, Muscles pain. Later – Dry, Hacking, Cough with retrosternal burning.
Complications	Organisation, Pleural effusion, Empyema, Lung abscess, Metastatic infection.	Organisation, Pleural effusion, Lung abscess, Empyema.	Interstitial fibrosis and permanent damage.

CLINICAL FEATURES : This disease starts with-

i. Malaise.

ii. Headache.

iii. Muscles aches.

iv. High grade fever.

v. Chills.

vi. Cough.

vii. Tachypnoea.

viii. Abdominal pain.

ix. Water diarrhoea.

x. Proteinuria.

xi. Mild hepatic dysfunction.

Source : Textbook of pathology ( Harsh Mohan ) 7th edition

Related Posts -

• Pneumonia
• Lobar Pneumonia.
• Lobular Pneumonia or Bronchopneumonia.
• Interstitial Pneumonia
• Legionella Pneumonia.
• How to failed lungs defense mechanism.
• Textbook of pathology (Harsh Mohan ) 7th edition.

Pneumonias (Lobular pneumonia)

Bronchopneumonia (Lobular Pneumonia)

Definition : Lobular pneumonia is the infection of the terminal bronchioles that extends into the surrounding alveoli resulting in patchy consolidation of the lung. Founds in extreme of ages ( infants and old age).

Etiology : The common organism that responsible for bronchopneumonia is -

1. Staphylococci

2. Streptococci

3. Pneumococci

4. Klebsiella pneumoniae

5. Haemophilus influenzae

6. Gran-negative bacilli ( pseudomonas and caliform bacteria ).

MORPHOLOGICAL FEATURES :

Grossly : Lobular pneumonia is identified by patchy areas of red and grey consolidation at the affected part. Frequently found bilaterally and more common in lower zone of the lungs. Cut surface shows patchy, consolidated lesions are dry, granular, firm, red or grey in color, 3-4 cm in diameter, slightly elevated over the surface and are commonly centred around a bronchiole. 
Histologically : 
i. Acute bronchiolitis.
ii. Suppurative exudate, consisting specially neutrophils in the peribronchiolar alveoli.
iii. Thickening of the alveolar septa by congested capillaries and leucocytic infiltration.
iv. Less involved alveoli contain oedema fluid.

Features	Lobar Pneumonia	Lobular Pneumonia	Interstitial Pneumonia
Definition	It is an acute bacterial infection of a part of lobe or entire lobe or even two lobes of one or both the lungs.	It is the infection of terminal bronchioles that extend into the surrounding alveoli resulting in patchy consolidation of lung.	It is characterized by patchy inflammatory changes generally confined to interstitial tissue without any alveolar exudates.
Etiology	Pneumococci, Staphylococcal pneumonia.	Staphylococci, Streptococci etc.	Respiratory Syncytial Virus (RSV), Mycoplasma pneumoniae.
Morphology	Stage of congestion (1-2 days), Red hepatisation  (2-4 days), Grey hepatisation (4-8 days), Resolution (8-9 days)	Patchy consolidation with central granularity, alveolar exudate, thickened septa.	Patchy to massive and widespread consolidation of one or both the lungs.
Clinical features	Shaking, Chills, Fever, Malaise, Chest pain, Dyspnoea, Tachycardia, Tachypnoea and Cyanosis.	Shaking, Chills, Fever, Malaise, Chest pain, Dyspnoea, Tachycardia, Tachypnoea and Cyanosis, Mottled patches lung in X-rays.	Initially – Fever, Headache, Muscles pain. Later – Dry, Hacking, Cough with retrosternal burning.
Complications	Organisation, Pleural effusion, Empyema, Lung abscess, Metastatic infection.	Organisation, Pleural effusion, Lung abscess, Empyema.	Interstitial fibrosis and permanent damage.

COMPLICATIONS : Resolution of bronchopneumonia is uncommon. There is generally some amount of bronchioles are destructed resulting in foci of bronchiolar fibrosis that may cause bronchiectasis, pleural effusion, empyema, lung abscess and organisation.

CLINICAL FEATURES : Lobular pneumonia are common in infants or elder age persons.
i. There may be history of preceding bedridden illness, chronic debility (weakness), flu, measles, aspiration of gastric contents or upper respiratory infection.
ii. There is initial (2-3 days) appearance of features of acute bronchitis.
iii. Blood examination usually shows neutrophilic leucocytosis.
iv. Chest X-rays shows mottled, focal opacity (lack transparency) in both the lungs, specially in the lower zones.

Source : Textbook of pathology (Harsh Mohan) 7th edition

Related Post -

• Pneumonia
• Lobar Pneumonia.
• Lobular Pneumonia or Bronchopneumonia.
• Interstitial Pneumonia
• Legionella Pneumonia.
• How to failed lungs defense mechanism.
• Textbook of pathology (Harsh Mohan ) 7th edition.

Pneumonias (Lobar Pneumonia)

Pneumonias 

Definition : It is an acute inflammation of lungs parenchyma with consolidation distal to terminal bronchioles ( consisting of the respiratory bronchiole, alveolar ducts, alveolar sacs and alveoli ).It may be infective and non-infective.

Pathogenesis : Microorganism can enter into the lungs by following route after failure of defensive mechanism -
i. Inhalation of air microbes.
ii. Aspiration of the microbes from the nasopharynx or oropharynx.
iii. Haematogenous spread from a distant focus of infection such as - vector population, environmental characteristics.
iv. Direct spread from a adjoining site of infection.

Classification :
1. On the basis of anatomical regions -

• Lobar Pneumonia
• Bronchopneumonia or Lobular Pneumonia
• Interstitial Pneumonia

Features of lobar and lobular pneumonia

2. On the basis of clinical aspects -

• Community-acquire Pneumonia
• Health care-associated Pneumonia (Hospital acquired Pneumonia)
• Ventilator-associated Pneumonia

3. On the basis of etiology and pathogenesis -

• Bacterial Pneumonia (Lobar pneumonia, Lobular pneumonia )
• Viral Pneumonia (Primary atypical pneumonia)
• Fungal pneumonia ( Pneumocystis pneumonia, Aspergillosis, Mucormycosis, Candidiasis, Histoplasmosis, Cryptococcosis, Coccidioidomycosis, Blastomycosis)
• Non infective pneumonias ( Aspiration pneumonia, Hypostatic pneumonia, Lipid pneumonia)

LOBAR PNEUMONIA

How To Failed Lungs Defense Mechanism

How To Failed Lungs Defense Mechanism

The lungs are bacteria free in normal condition because presence of high defense mechanism such as-

1.  Nasopharyngeal filtering action
2. Mucociliary action of the lower respiratory airways
3. The presence of alveolar macrophages and immunoglobulins. 

Failure of these defense mechanism in certain conditions and may developed pneumonia -
1. Altered consciousness : The oropharyngeal contents may be aspirated and causing unconsciousness such as in -

• Coma
• Cranial Trauma
• Seizures
• Cerebrovascular accidents
• Drugs overdose
• Alcoholism

2. Depressed cough and glottic reflexes : In this condition aspirated gastric contents in to the lungs such as in -

• Old age
• Traumatic pain or Thoracoabdominal surgery
• Neuromuscular disease
• Weakness due to malnutrition
• Kyphoscoliosis
• Severe Obstructive Pulmonary Disease
• Endotracheal intubation
• Tracheostomy

3. Impaired mucociliary transport : The normal protection offered by mucus covered ciliated epithelium in the airways from the larynx to terminal bronchioles. It is impaired or destroyed in many conditions i.e.

• Cigarette smoking
• Viral respiratory infections
• Immotile cilia syndrome
• Inhalation of hot or corrosive gases
• Old age

4. Impaired alveolar macrophage function : Alveolar macrophages function are impaired in such conditions that cause pneumonia -

• Cigarette smoking
• Hypoxia
• Starvation
• Anaemia
• Pulmonary Oedema
• Viral respiratory infections

5. Endobronchial obstruction : Endobronchial obstruction may cause pneumonia that may occurs in such conditions -

• Tumour
• Foreign body
• Cystic fibrosis
• Chronic bronchitis

6. Immunocompromised conditions : Disorders of lymphocytes including congenital and acquired immunodeficiencies -

• AIDS
• Debility
• Senility
• Immunosuppressive therapy
• Granulocyte abnormalities

Related Posts :-

• Pneumonia
• Lobar Pneumonia.
• Lobular Pneumonia or Bronchopneumonia.
• Interstitial Pneumonia
• Legionella Pneumonia.
• How to failed lungs defense mechanism.
• Textbook of pathology (Harsh Mohan ) 7th edition.

Source : Textbook of pathology (Harsh Mohan) 7th edition

Pneumothorax

Pneumothorax

An accumulation of air in the pleural cavity called pneumothorax.

Classification : 

1. Spontaneous pneumothorax

2. Traumatic pneumothorax

3. Therapeutic or artificial pneumothorax

1. Spontaneous Pneumothorax : It occur due to spontaneous rupture of alveoli in any disease of lungs.

Causes : Most commonly associated with - 

i. Emphysema

ii. Asthma

iii. Tuberculosis

Other causes are : 

i. Chronic bronchitis, Bronchiectasis, Pulmonary infarction and Bronchial cancer ( in old patient).

ii. Recurrent spontaneous rupture of peripheral subpleural blebs without any cause called Spontaneous Idiopathic Pneumothorax ( in young patient ).

2. Traumatic Pneumothorax : It is occur due to traumatic cause called traumatic pneumothorax.

Causes : 

i. Chest wall or lungs trauma.

ii. Ruptured oesophagus or stomach.

iii. Surgical operation of the thorax.

3. Therapeutic or artificial Pneumothorax : It is the first positive treatment of tuberculosis in which air was introduced into the pleural sac so as to collapse the lungs and limit its respiratory movement. That is now replaced by chemotherapy.

Clinical Features : If the quantity of air in the pleura is small, it is reabsorbed but if the quantity of air is in large amount that cause -

i. Dyspnoea

ii. Chest pain.

iii. Lung collapse

iv. Push the mediastinum to the unaffected side.

v. Lungs act as a flap-valve and create Tension Pneumothorax (it  allows entry of air during inspiration but does not permit its escape during expiration).

vi. Circulatory failure.

Source : Textbook of pathology (Harsh Mohan) 7th edition

Chylothorax

Chylothorax

Accumulation of milky fluid of lymphatic origin into the pleural cavity called chylothorax. It is occur mostly left side. Chylous effusion is milky due to high content of finely emulsified fats in the chyle. 

Causes : 

i. Most common cause are rupture of the thoracic duct by trauma.

ii. Obstruction of the thoracic duct by malignant tumors and malignant lymphomas.

Source : Textbook of pathology (Harsh Mohan) 7th edition

Haemothorax

Haemothorax

Accumulation of pure blood in the pleural cavity called haemothorax.

Causes : 

i. Trauma to the chest wall or thoracic viscera.

ii. Rupture of aortic aneurysm.

ANEURYSM : an excessive localized enlargement of an artery cause by weakening of the artery wall.

Complications : Remove the blood from the pleural cavity early as soon as possible. Otherwise the blood will be clot and organise, resulting in fibrous adhesions and obliteration of the pleural cavity.

Source : Textbook of pathology ( Harsh Mohan) 7th edition 

Hydrothorax

Hydrothorax

Accumulation of serous fluid within the pleural cavities called hydrothorax. It may be unilateral or bilateral depending upon the causes.

Causes :

i. Congestive heart failure (most common cause of bilateral hydrothorax).

ii. Renal failure

iii. Cirrhosis of liver

iv. Meig's syndrome (triad of benign Ovarian tumor with Ascites and Pleural effusion)

v. Pulmonary Oedema

vi. Primary and secondary tumours of the lungs.

On Examination :

i. color of serous fluid are clear and straw-colored with characteristically  transudate.

ii. Specific gravity is under 1.012

iii. Protein contents below 1gm/dl and find little cellular content also.

Clinical Features : 

• If the fluid collection in pleural cavity is less than 300 ml ( normal less than 15 ml) no signs or symptoms are produced and may be appear in chest X-rays in standing posture as obliterated costodiaphragmatic angle.
• If fluid collection in pleural cavity is more than 300 ml that is the part of characteristic opaque radiographic appearance to the affected side with deviation of trachea to the opposite side.
• Respiratory embarrassment (rapid shallow breathing with inspiratory dyspnoea) and dyspnoea are also produced.

Source : Textbook of pathology (Harsh Mohan) 7th edition

Pleuritis

Pleuritis or Pleurisy

Definition : Inflammation of the pleura ( covering of the lungs) called pleuritis or pleurisy.

Classification :

1. Serous, Fibrinous and Serofibrinous Pleuritis
2. Suppurative Pleuritis (Empyema Thoracis)
3. Haemorrhagic Pleuritis

1. Serous, Fibrinous and Serofibrinous Pleuritis : Acute inflammatin of the pleural sac (acute pleuritis) can results in serous, serofibrinous and fibrinous exudate.

Causes : 

INFECTIOUS CAUSE :

i. Tuberculosis

ii. Pneumonias

iii. Pulmonary infarcts

iv. Lung abscess

v. Bronchiectasis

OTHER CAUSES :

i. Collagen diseases - rheumatoid arthritis and disseminated lupus erythematous.

ii. Uraemia ( increase level of urea in blood)

iii. Diffuse systemic infections - typhoid fever, tularaemia, blastomycosis and coccidioidomycosis.

iv. Irradiation of lung tumours

Clinical Features : 

i. Chest pain on breathing

ii. Friction rub is audible on auscultation

iii. After resolution, exudate become reabsorbed or minimized

Complications : Repeated attacks of pleurisy may leads fibrous adhesions and oblitreration of the pleural cavity.

2. Suppurative Pleuritis ( Empyema Thoracis) : Serofibrinous effusion converts into purulent exudate due to bacterial or mycotic infections called suppurative pleuritis or empyema thoracis.

Causes : 

i. Direct spread of pyogenic infection from the lungs ( most common cause)

ii. Direct extension from subdiaphragmatic abscess or liver abscess.

iii. Penetrating injuries to the chest wall.

iv. Haematogenous or lymphatic routes (occasionally)

On Examination : 
i. In empyema, the exudate is yellow green, creamy pus that accumulates in large quantity.
ii. Empyema is finally replaced by granulation tissue and fibrous tissue.

Complications : 
i. When tough fibrocollagenic adhesions develop which obliterate the cavity.
ii. In later stage calcification may occur.
iii. Finally develop serious respiratory difficulty due inadequate pulmonary expansion.

3. Haemorrhagic Pleuritis : It is different from haemothorax because it have inflammatory cells or exfoliated tumour cells in the exudate.

Causes : 
i. Metastatic involvement of the pleura.
ii. Bleeding disorders.
iii. Rickettsial diseases - spotted fever, typhus fever rickettsioses, scrub typhus, anaplasmosis and ehrlichioses.

Source : Textbook of pathology (Harsh Mohan) 7th edition