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.