Classification

Pneumonia can be classified according to etiology, location acquired, clinical features, and the area of the lung affected by the pathology.

• Primary pneumonia: no apparent preexisting conditions that may predispose to pneumonia

• Secondary pneumonia

  • Bronchial asthma, COPD, heart failure, cystic fibrosis

  • Viral upper respiratory tract infections with bacterial superinfection

  • Anatomical abnormalities such as tubercular caverns, bronchial tumors, or stenosis (postobstructive pneumonia) [9]

  • Aspiration pneumonia

• Community-acquired pneumonia (CAP): pneumonia that is acquired outside of a healthcare establishment

• Hospital-acquired pneumonia (HAP): nosocomial pneumonia, with onset > 48 hours after admission

  • Ventilator-associated pneumonia (VAP): pneumonia occurring in patients who are on mechanical ventilation breathing machines in hospitals (typically in the intensive care unit)

• Healthcare-associated pneumonia (HCAP): pneumonia that is acquired in healthcare facilities (e.g., hospital, nursing homes, hemodialysis centers, and outpatient clinics); this terminology is no longer recommended but is included for historical purposes.

• Typical pneumonia

  • Pneumonia featuring classic symptoms (typical findings on auscultation and percussion)

  • Manifests as lobar pneumonia or bronchopneumonia

• Atypical pneumonia

  • Pneumonia with less distinct classical symptoms and often unremarkable findings on auscultation and percussion

  • Manifests as interstitial pneumonia

Area of lung affected by the pathol

• Lobar pneumonia: pneumonia affecting one lobe of a lung

  • Multilobar pneumonia refers to the involvement of multiple lobes in a single lung or both lungs.

  • Panlobar pneumonia involves all the lobes of a single lung.

• Bronchial pneumonia: pneumonia affecting the tissue around the bronchi and/or bronchioles

• Interstitial pneumonia: pneumonia affecting the tissue between the alveoli

• Cryptogenic organizing pneumonia (formerly known as bronchiolitis obliterans organizing pneumonia): a noninfectious pneumonia of unknown etiology characterized by the involvement of the bronchioles, alveoli, and surrounding tissue