ACP L18 Pathology of Lung infections Flashcards
State the differences between broncho-/lobar pneumonia interstitial pneumonia. (3)
- Site
Bronchopneumonia: alveoli
Interstitial pneumonia: interstitium - Causative agents
Bronchopneumonia: Bacteria, fungi
Interstitial pneumonia: Virus, protozoa, Mycoplasma - Inflammatory cells
Bronchopneumonia: Neutrophils, then macrophages
Interstitial pneumonia: Lymphocytes, eosinophils, macrophages
What is the difference in site between bronchopneumonia and lobar pneumonia?
Bronchopneumonia:
- starts at bronchi/bronchioles, then alveoli
- focal and patchy consolidation affecting more than one lobes
Lobar pneumonia
- complete consolidation of one lobe
What happens in the following timeslots in the natural course in pneumonia?
Briefly describe what happens in the event.
- 24h
- Congestion
- vascular response
What happens in the following timeslots in the natural course in pneumonia?
Briefly describe what happens in the event.
2. 2-4 days
- 2-4 days: Red hepatisation
- alveolar cells filled with RBC, fibrin, neutrophils
- acute inflammation
What happens in the following timeslots in the natural course in pneumonia?
Briefly describe what happens in the event.
3. 4-8 days
- 4-8 days: Grey hepatisation
- Red cells lysed by macrophages
- fibrinosuppurative exudate persists
- chronic inflammation
What happens in the following timeslots in the natural course in pneumonia?
Briefly describe what happens in the event.
- > 8 days
> 8 days
- Resolution
- Exudate is digested to debris > ingested by mmacrophages or organised by fibroblasts
- repair by fibrosis - Complications (if any)
- abscess: collection of pus in a newly formed cavity
- empyema: collection of pus in pleura
- sepsis
What is the important negative: nodular lesion in pneumonia?
Tumor
Important negative: cystic lesion in pneumonia?
Usual interstitial pneumonia (honeycombing)
important negative: pleural lesion in pneumonia?
occupation: asbestosis
What are the 4 clinically classified pneumonia?
- Community-acquired acute
- Community-acquired atypical
- Nosocomial
- Aspiration
Give examples of causative agents in community-acquired acute pneumonia. (5)
- Streptococcus pneumoniae (MC)
- Haemophilus influenzae
- MC in acute exacerbation in COPD - Moraxella catarrhalis
- Staph. Aureus
- secondary infection to viral infection, IVDA (IV drug abuse) , high incidence of complications (abscess, empyemia) - Klebsiella pneumoniae
- High grade fever
- Productive cough, purulent (pus containing) sputum
- WBC increased
- Consolidation in CXR
D(x)?
Any other clinical manesfistations ?
Community acquired acute pneumonia
- Abrupt onset
- CXR consolidation due to alveolar exudate
- Non-productive cough, non-purulent sputum
- Patchy infiltrates, no consolidation in CXR
- Low grade fever
D(x)?
Any other clinical manesfistations ?
Community acquired atypical pneumonia
- WBC normal
Causative agents of community-acquired atypical pneumonia? (4)
- Mycoplasma pneumoniae (MC)
- Chlamydophila pneumoniae
- Legionella pneumophilia
- artificial aquatic environment, organ transplant - Virus: SARS, H5N1
Causative agents of nosocomia pneumonia? (4)
- Pseudomonas aeruginosa
- immunocompromised
- e.g. neutropenia, burns, mechanical ventilation - Enterobacteriaceae
- S. aureus
Anaerobic oral flora, stroke, unconsciousness and repeated vomiting, necrotising pneumonia and abscess - related to which type of pneumonia?
Aspiration pnuemonia
Which side of the lung is more usually involved in aspiration pneumonia? why?
Right: shorter and straighter RMB
State the pathology of SARS - coronavirus.
infection of the lung epithelial cells
- Interstitial inflammation - diffuse alveolar damage (DAD) (pink hyaline membranes line the alveolar walls)
- Cytopathic effect - Multinucleated giant cells formed by pneumocytes and macrophages
- Organization - fibrosis and macrophages
Which of the following about Avian flu (H5N1) is correct?
A. Most fatal cases seen in young children and physically fit adults
B. it is airborne rather than by droplets
C. associated with hemophagocytic syndrome, an overeactive immun respone
All of the above
Which of the following about pulmonary tuberculosis is incorrect?
A. it is caused by mycobacterium tuberculosis B. fever C. diarrhea D. drenching night sweat E. weight gain
C, not mentioned
What kind of response granulomatous inflammation in TB belongs to?
T cell mediated hypersensitivity response
What are the 3 important microscopic features of granulomatous inflammation in TB?
- Collection of epitheloid histiocytes surrounding
- Caseous necrotic center
- Langhan’s giant cells
- lymphocytes (outer rim of epitheloid histiocytes)
> > > cavity
What is primary TB?
subpleral lesion with Ghon focus and Ghon complex (Ghon focus + ipsilateral hilar lymph nodes)
State the 3 fates of primary TB.
- Resolve - healed scar
- Progress to hematogenous dissemination (miliary TB)
- Latent - reactivate as secondary TB
Secondary TB characteristics?
= reactivation of a previous primary TB site when immunocompromised
- lung- localised, caseating, cavitatory lesions
- upper zone due to highest ventilation (M tuberculosis is a strict aerobe)
- may progress to miliary TB
State all the fungal causative agents of pneumonia in immunocompromised hosts.
- Candidia
- Aspergillus
- Cryptococcus
- Pneumocystis jirovecii
Candidia albicans resembles pneumocystis pneumonia, with?
bilateral nodular infiltrates
Pneumocytis jiroveci infects mostly immunocompromised patients, e.g. ?
HIV patients
Which are the 3 types of aspergillus fungal infections? briefly describe.
- Aspergilloma
- growth of aspergillus in pre-existing pulmonary cavities - Invasive aspergillosis
- necrotizing pneumonia, fungal hyphae: invasion of blood vessels, systemic dissemination - Allergic bronchopulmonary aspergillosis
- hypersensitivity reaction against aspergillus in the bronchi, increase IgE and eosinophil
What is the viral causative agents in pneumonia?
Results in patients?
Cytomegalovirus (CMV)
- CMV mononucleosis > fever, lymphadenopathy in immunocompetent patients
- in immunocompromised patients: disseminated diseases, life-threatening, nuclear and cytoplasmic inclusions in lungs
List 4 mechanisms of entry of lung abscesses.
ABCS
Aspiration: anaerobes, more common on right lung
Bronchiol obstruction: bronchiectasis, CA lung
Complication of bacterial pneumonia/mycotic infection
Septic embolism: IE
