Respiratory system,pneumonias

1. The Lung
(Pulmonary infections – pneumonias)
Dr. Jyoti M.D.
Assistant Professor
Department of Pathology,
AIMSR, chittoor.

2. Pulmonary Infections
• Pneumonia is inflammation and consolidation of
the lung parenchyma.
• Result from impaired defense mechanisms or
lowered host resistance in general.
• One type of pneumonia sometimes predisposes
to another, especially in debilitated patients.
2

3. Factors Predisposing to Bacterial
Pneumonia
• Loss of cough reflex (e.g.,
from coma, anesthesia)
• Injury to mucociliary apparatus (e.g.,
from smoke, viral infections or genetic
disturbances; immotile cilia syndrome)
• Interference with phagocytic or bactericidal
action of alveolar macrophages
(e.g., from alcohol, smoke)
• Pulmonary edema and congestion
• Accumulated secretions (e.g.
from cystic fibrosis, bronchial obstruction)

4. Pneumonia syndromes
Dept of pathology, CHRI 4

5. Pneumonia Syndromes
Community-Acquired Acute Pneumonia
 Streptococcus pneumoniae (pneumococcus)
 Haemophilus influenzae
 Legionella pneumophila
 Klebsiella pneumoniae
Community-Acquired atypical pneumonia
 Mycoplasma pneumoniae
 Chlamydia spp
 Viruses: RSV, parainfluenza (children);
influenza A & B (adults); SARS virus
5

6. Pneumonia Syndromes (Contd)
Nosocomial Pneumonia ( hospital acquired)
 Gram-negative rods (Klebsiella spp) &
Pseudomonas spp
 Staphylococcus aureus (methicillin-resistant)
Aspiration Pneumonia
 Anaerobic oral flora (Bacteroides,
fusobacterium) admixed with aerobic bacteria
(Streptococcus pneumoniae, H.influenzae &
pseudomonas)
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7. Pneumonia Syndromes (Contd)
Chronic Pneumonia
 Nocardia, Actinomyces
• Granulomatous: M.tuberculosis & atypical
mycobacteria, Histoplasma capsulatum
Necrotizing Pneumonia & Lung Abscess
 Anaerobic bacteria (common) with or without
mixed aerobic infection
 Staphylococcus aureus, Klebsiella pneumoniae,
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8. Pneumonia Syndromes (Contd)
Pneumonia in Immunocompromised Host
 Cytomegalovirus (CMV)
 Pneumocystis carinii
 Mycobacterium avium-intracellulare (MAI)
 Invasive aspergillosis
 Invasive candidiasis
8

9. Community acquired
pneumonia
• Definition:
refers to lung infection in otherwise healthy
individuals that is acquired from the
environment ( contrast to hospital acquired
pneumonia)
May be bacterial or viral
Bacterial invasion of lung parenchyma
causes inflammatory exudate in alveoli-
causing consolidation of lung
Dept of pathology, CHRI 9

10. • Pathogenesis
Microbes enter lungs through:
a) inhalation of microbes from air
b) aspiration of organisms from
nasopharynx or oropharynx
c) hematogenous spread
d) direct spread from an adjoining site.
Dept of pathology, CHRI 10

11. Bacterial Pneumonia (Two types)
Bronchopneumonia
refers to patchy
consolidation
in one or more lobes
Usually basal.
Lobar pneumonia
refers to
consolidation
of an entire lobe.

12. Stages in lobar pneumonia
• Congestion
• Red hepatisation
• Grey hepatisation
• Resolution
Dept of pathology, CHRI 12

13. Four stages in Lobar
pneumonia
1)Congestion – early inflammatory response
gross : lung is heavy, boggy & red.
microscopy: vascular engorgement(congested
capillaries) & some edema fluid in alveoli along
few intra alveolar neutrophils , & RBC, bacteria.
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14. • 2) RED HEPATIZATION –( early
consolidation)
Gross : Red firm and airless lung with liver
like consistency.
Microscopy:
Numerous neutrophils, red cells ,
fibrin material in alveoli ( odema fluid is
replaced)
Dept of pathology, CHRI 14

15. 3)GREY HEPATIZATION – ( late consolidation)
Gross : greyish brown, dry lung surface, liver like
consistency.
Microscopy:
Progressive disintegration of red cells &
inflammatory cells.
. Persistence of fibrinosuppurative exudate
separated from alveolar walls by a space
Macrophages appear
Fewer organisms .
Dept of pathology, CHRI 15

16. 4)RESOLUTION –
• exudate undergoes enzymatic digestion to form
debris that is removed by macrophages.
• 8th or 9th day.
• If antibiotics are given- starts on 3rd day .
• Microscopy: Macrophages- contain debris,
neutrophils.
Broken fibrin strands
Progressive removal of debris and fluid content by
expectoration and lymphatics.
Dept of pathology, CHRI 16

17. Lobar Pneumonia
17
Grey hepatization.
The lower lobe is
Uniformly
Consolidated.

18. Dept of pathology, CHRI 18

19. Bronchopneumonia
• Infection of terminal bronchioles that
extends into the surrounding alveoli,
results in patchy consolidation.
• Condition is frequent in extremes of life.
Dept of pathology, CHRI 19

20. Bronchopneumonia( lobular
pneumonia)
20

21. • Gross :
Lung shows patches of consolidation ( 3
to 4cm),
Dry,granular,firm,red or grey in clour
Microscopy: acute Suppurative
inflammation ( neutrophils) in
peribronchiolar alveoli.
Thick alveolar septa due to congested
capillaries & leucocyte infiltration.
Dept of pathology, CHRI 21

22. Common Clinical Manifestation of
Bacterial Pneumonia
• Fever and chills
• Malaise
• Productive cough, occasionally
hemoptysis
• Pleuritic chest pain (if pleuritis is present)
• Tachycardia
• Tachypnea
22

23. Complications of Bacterial
Pneumonia
1. Abscess
2. Empyema
3. Organization of exudate with fibrosis
4. Bacteraemia with dissemination of
organisms to heart valves, brain, etc.
5. Pleuritis
6. Pleural effusion
7. Bronchopleural fistula
23

24. Identification of the organism causing the
disease and
Identifying the extent of disease
are most important from a clinical aspect.
Dept of pathology, CHRI 24

25. Bacterial Pneumonia
Diagnostic Techniques
1. Gram stain of sputum (expectorated specimen
or transtracheal aspirate)
2. Chest x-ray
3. Sputum culture and sensitivity
4. Blood cultures (may detect bacteraemia)
5. Other body fluids may also be cultured if
present and indicated
6. Blood gases if there is significant hypoxemia
7. CBC
25

26. Community-Acquired
Pneumonia
1. Mild to moderate disease – treat with
appropriate antibiotics as out patients
2. Indications for hospitalization include:
a) Severe dyspnea or hypoxemia
b) Empyema or extra-pulmonary foci of
infection
c) Other significant underlying disease, such
as CHF, COPD, etc.
d) Severe systemic manifestations, such as
delirium
26

27. Community acquired atypical
pneumonias
• Seen in early childhood; or in
immunocompromised patients of any age
• Patchy or lobar areas of congestion( no
consolidation)
• Inflammation is confined to alveolar septa &
pulmonary interstitium
27

28. Organisms causing atypical
pneumonia
• Mycoplasma pneumoniae
• Chlamydiae
• RSV
• Parainfluenza virus
• CMV
• HSV
Dept of pathology, CHRI 28

29. Microscopy
• Interstitial inflammation.
• Lobar or patchy congestion .( no
consolidation) No alveolar exudate
Hence , atypical
• Necrotising bronchiolitis- necrosis of the
bronchiolar epithelium, mononuclear cell
infiltration.
• Reactive proliferation of the epithelium of
bronchioles & alveoli.
Dept of pathology, CHRI 29

30. Viral Pneumonia
30

31. Cytomegalovirus Pneumonia
• Occurs predominantly in immuno-
compromised patients
• Clinical presentation: fever, dyspnea, non-
productive cough and diffuse lung
infiltrates
31

32. CMV Pneumonia
32

33. Pneumocystis Pneumonia
• Occurs in immunocompromised individual
• Characteristic pathologic feature is the intra-
alveolar foamy exudate containing organisms
and an interstitial pneumonia
• Variable clinical presentation:
1) May have minimal symptoms
2) Fever, dyspnea, dry cough
3) May progress to respiratory failure
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34. Pneumocystis Pneumonia
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35. Pulmonary Fungal Infections
1. Histoplasmosis
2. Coccidiodomycosis
3. Cryptococcosis
4. North American Blastomycosis
5. Aspergillosis
35

36. Histoplasmosis
1. Endemic in- Mississippi + Ohio Valleys,&
Carribean islands.
2. Acquired by inhalation of soil
contaminated with bird/ bat droppings
with spores.
3. Intracellular pathogen( like mycobacteria)
4.Pathology: Granulomatous disease ,
undergo caseating necrosis
Variable clinical presentation.
36

37. Histoplasmosis
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38. Pulmonary Aspergillosis
1. Allergic bronchopulmonary
aspergillosis- hypersensitivity
reaction associated with asthma
2. Aspergilloma
3. Invasive aspergillosis
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39. Aspergilloma
Fungal growth
in pre-existent
cavity
(as fungus ball)
39

40. Invasive Pulmonary
Aspergillosis
• Usually an opportunistic infection in
immuno-compromised patients
• Often have vascular invasion 
thrombosis + infarct
• Necrotising pneumonia- target lesions are
seen( sharply delineated gray foci with
hemorrhagic borders)
40

41. Invasive Pulmonary
Aspergillosis
41

42. Cryptococcosis
1. Natural habitat is soil, pigeon
droppings
2. Capsulated organism- red colour
with mucicarmine.
3. Meningoencephalitis in
immunocompromised individuals.
4. Pathology: varies from no reaction
to necrotizing granulomas;
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43. Cryptococcosis
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44. Coccidiodomycosis
1. Coccidiodes immitis
2. Endemic in Southwest &western US
3. Caused by inhalation of spores-soil
4. Variable clinical presentation
5. Pathology: Necrotizing
granulomatous inflammation
44

45. Coccidiodomycosis
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46. Lung abscess
• Localised area of necrotic tissue with
suppuration.
Dept of pathology, CHRI 46

47. Mechanisms for Lung abscess
1. Aspiration of infective material, usually in
the setting of altered consciousness
(most frequent)
2. Post-pneumonia abscess (especially
seen with staph. aureus, Klebsiella
pneumoniae, and type 3 pneumococcus)
3. Septic embolism
4. Neoplasm with secondary infection
5. Misc. such as direct penetration, etc.
47

48. Lung Abscess
48
Abscess

49. • Gross :
Destruction of lung parenchyma with
suppurative exudate in the lung cavity.
Microscopy: few mm to several cm in
diameter;
surrounded by area of acute inflammation.
Later , chronic inflammatory cells
Fibrous wall develops after a long time.
Dept of pathology, CHRI 49

50. Clinical features
• Fever,
• Malaise,
• Weight loss
• Cough
• Purulent expectoration
• Hemoptysis
• Clubbing .
Dept of pathology, CHRI 50

51. Thank you
Dept of pathology, CHRI 51