MORPHOLOGICAL FEATURES OF PNEUMONIA.....

This presentation provides a detailed exploration of the morphological and microscopic features of pneumonia, covering its histopathology, classification, and clinical significance. Designed for medical students, pathologists, and healthcare professionals, this lecture differentiates bacterial vs. viral pneumonia, explains lobar, bronchopneumonia, and interstitial pneumonia, and discusses diagnostic imaging patterns.

💡 Key Topics Covered:
✅ Normal lung histology vs. pneumonia-affected lung
✅ Morphological changes in lobar, bronchopneumonia, and interstitial pneumonia
✅ Microscopic features: Fibroblastic plugs, alveolar septal thickening, inflammatory cell infiltration
✅ Stages of lobar pneumonia: Congestion, Red hepatization, Gray hepatization, Resolution
✅ Common causative pathogens (Streptococcus pneumoniae, Klebsiella pneumoniae, Mycoplasma, etc.)
✅ Clinical case study with diagnostic approach and differentials

🔬 Who Should Watch?
This is an essential resource for medical students, pathology trainees, and respiratory health professionals looking to enhance their understanding of pneumonia’s morphological aspects.

1. MORPHOLOGICAL FEATURES OF
PNEUMONIA
By: Dr. Maheen Mazhar Ali

2. LEARNING OBJECTIVES
At the end of this session, students should be able to:
Differentiate between normal lung histology and
histology in pneumonia.
Correlate clinical features to diagnose pneumonia.
Identify the morphological and microscopic
features of pneumonia.
Differentiate between bacterial and viral
pneumonia.

3. NORMAL LUNG
The lungs are a pair of primary organs of respiration,
present in the thoracic cavity beside the
mediastinum. They are covered by a thin double-
layered serous membrane called the pleura.

4. ALVEOLI
The alveoli are cup shaped structures having very thin
walls through which gaseous exchange takes place.
The pulmonary alveoli are lined by two types of
epithelial cell:
Type I Alveolar cells.
Type II Alveolar cells.

5. ALVEOLI

6. ALVEOLI

7. PNEUMONIA
Infection of the lung parenchyma.
Occurs when normal defenses are impaired (e.g.,
impaired cough reflex, damage to mucociliary
escalator, or mucus plugging)

8. TYPES OF PNEUMONIA
SYNDROME
Community Acquired Acute Pneumonia
Health Care Associated Pneumonia
Hospital Acquired Pneumonia
Aspiration Pneumonia
Chronic Pneumonia
Necrotizing Pneumonia & Lung abscess
Pneumonia in the immunocompromised host

9. TYPES OF PNEUMONIA
SYNDROME

10. TYPES OF PNEUMONIA
SYNDROME

11. TYPES OF PNEUMONIA
SYNDROME

12. TYPES OF PNEUMONIA
SYNDROME

13. CASE SCENARIO
A 35-year-old male presents with high grade fever
and cough. He was well until 3 days earlier, when he
suffered the onset of nasal stuffiness, mild sore throat,
and a cough productive of small amounts of clear
sputum.

14. CASE SCENARIO
Give your provisional diagnosis?
How will you investigate?
Give differential diagnosis?
What can be the complications of this disease?

15. MICROSCOPIC FEATURES
Fibroblastic plugs in alveolar sacs and ducts
(organizing pneumonia) and bronchiolar lumen.
Formed by spindled fibroblasts in pale staining
matrix of immature loose collagen with polypoid
shape (Masson body).
Thickened alveolar septa with lymphocytes,
plasma cells and histiocytes.

16. PNEUMONIA MORPHOLOGY
Three patterns are classically seen on chest x-rays:
Lobar pneumonia
Bronchopneumonia
Interstitial pneumonia

17. LOBAR PNEUMONIA
Characterized by consolidation of an entire lobe
of the lung.
Usually bacterial; most common causes are
Streptococcus pneumoniae (95%) and Klebsiella
pneumoniae.

18. LOBAR PNEUMONIA

19. LOBAR PNEUMONIA
Classic gross phases of lobar pneumonia:
1. Congestion- due to congested vessels and edema.
2. Red hepatization-due to exudate, neutrophils, and
hemorrhage filling the alveolar air spaces, giving the
normally spongy lung a solid consistency.
3. Gray hepatization-due to degradation of red cells
within the exudate.
4. Resolution.

20. LOBAR PNEUMONIA

21. LOBAR PNEUMONIA
Red hepatization Gray hepatization

22. BRONCHOPNEUMONIA
Characterized by scattered patchy consolidation
centered around bronchioles; often multifocal
and bilateral.
Caused by a variety of bacterial organisms
(Staphylococcus aureus, Haemophilus influenzae,
Pseudomonas aeruginosa, Moraxella catarrhalis,
Legionella pneumophila)

23. LOBAR PNEUMONIA
VS
BRONCHOPNEUMONIA

24. BRONCHOPNEUMONIA

25. BRONCHOPNEUMONIA

26. INTERSTITIAL (ATYPICAL)
PNEUMONIA
Characterized by diffuse interstitial infiltrates.
Presents with relatively mild upper respiratory
symptoms (minimal sputum and low fever);
'atypical' presentation.
Caused by bacteria or viruses (Mycoplasma
pneumoniae, Chlamydia pneumoniae, Respiratory
syncytial virus (RSV), Cytomegalovirus (CMV),
Influenza virus, Coxiella burnetii)

27. INTERSTITIAL (ATYPICAL)
PNEUMONIA

28. BACTERIAL VS VIRAL PNEUMONIA
Bacterial pneumonias are characterized by
predominantly intra-alveolar neutrophilic inflammation,
while viral pneumonia shows interstitial lymphocytic
inflammation.

29. PNEUMONIA
Clinical features include fever and chills,
productive cough with yellow-green (pus) or rusty
(bloody) sputum, tachypnea with pleuritic chest
pain, decreased breath sounds, dullness to
percussion, and elevated WBC count.
Diagnosis is made by chest x-ray, sputum gram
stain and culture, and blood cultures.

30. THANK YOU