Pathology of lung, upper airways and pleura

Pneumonias

• = infectious inflammation of lung
• 1. comm.- acq. acute pneumonia (bacteria)
• 2. atypical pneumonia (viruses, Mycoplasma, Chlamydia)
• 3. nosocomial pneumonia (gram-negative rods)
• 4. aspiration pneumonia (anaerobic oral flora)
• 5. chronic pneumonia (TBC)
• 6. necrotizing pneumonia / lung abscess
• anaerobic bacteria, S. aureus, K. pneumoniae
• 7. pneumonia in immunocompromised host
• CMV, P. carinii, atypical Mycobacteria, fungi

Bronchopneumonia

• Streptococci, Staphylococci, H. influenzae
• from lower airways  alveoli
• grossly
• patchy inflammatory consolidation
• bilateral basal localization
• 3-4 cm, red to yellow patches
• microscopically
• suppurative inflammation in bronchi + bronchioles + alveoli

Lobar pneumonia

• Streptococcus pneumoniae 1, 2, 3
• rapid spread within alveoli
• 1. congestion - heavy, red, boggy
• alveolar edema + neutrophils
• 2. red hepatization - liver-like consistency
• alveoli fulfilled by neutrophils, RBCs, fibrin
• fibrinous / fibrinopurulent pleuritis
• 3. gray hepatization - dry, firm
• RBCs lysis + fibrin persistance
• 4. resolution

Pneumonia - complications

• 1. lung abscess
• acute x chronic
• bronchogenic – S. aureus, K. pneumoniae
• x hematogenic (peripheral pyemia)
• bronchopleural fistulas – pneumothorax + empyema
• brain abscess + AA amyloidosis
• 2. empyema
• 3. lung fibrosis + pleural adhesions
• 4. bacteremia
• meningitis, arthritis, infective endocarditis

Atypical pneumonia

• viruses (influenza, adenovirus, RSV, CMV)
• Chlamydiae, Rickettsiae
• grossly
• patchy x segmental x lobular, red-blue, congested areas
• microscopically
• alveolar septa – edema + mononuclear infiltrate
• prognosis
• complete recovery
• bacterial superinfection
• ARDS