Lecture 9: Pathology of Pulmonary Infection Flashcards
Five ways the defense mechanisms of the lung could be damaged (predisposing infection)
Decreased cough, injury to mucociliary apparatus, interference with macrophages, pulmonary congestion, secretion accumulation
Two patterns of bacterial pneumonia
Bronchopneumonia (patchy, neutrophils, surrounds airways) vs Lobar (less common)
T/F: Any organism that can cause broncho can cause lobar pneumonia
True
Two most common bacterial causes of pneumona
Step pneumoniae, staph aureus
Pseudomonas is associated with what disease? Where do we see this infection histologically?
Cystic fibrosis; tend to center around blood vessels
Primary characteristic of bacterial pneumonia
Neutrophils in alveolar spaces
Who is at risk for community-acquired acute pneumonia?
Extremes of age, chronic disease, immune def, splenic problems
Community acquired bacterial pneumonia pathogens (5)
Strep pneumoniae, staph aureus, haemophilus influenzae, klebsiella, legionalla
Four risk factors for acquiring a nosocomial pneumonia
Severe disease, immunosuppression, prolonged antibiotic therapy, invasive devices (catheter/ventilator)
Nosocomial bacterial pneumonia pathogens (4)
Pseudomonas, staph aureus (MRSA), e coli, enterobacter
Outcomes of pneumonia (6)
Resolution, pleural effusion, empyema (pus in pleural space), fibrosis, abscess, bacteremia
Where is aspiration induced abscesses more common?
Right lung
Symptoms of lung abscess (5)
Cough, fever, foul-smelling sputum, chest pain, weight loss
Treatment of abscess
Antibiotics, but may require surgery
Gross features of lung abscess
Thick fibrotic wall surrounding lung pus
Microscopic features of lung abscess
Sea of neutrophils
What does atypical pneumonia mean?
Inflammation is alveolar septa and pulmonary interstitium (NOT in alveolar space)
What are the most common two causes of atypical pneumonia? Where in the community do we find atypical pneumonias?
Mycoplasm or viruses; schools/military camps
What is the atypical infiltrate?
Mononuclear inflammatory cells (lymphocytes)
Common pulmonary viruses (4)
Cytomegalovirus, herpes, adenovirus, influenza
CMV looks like…
Typically involves type 2 pneumocytes; intranuclear inclusions and cytoplasmic inclusions within megalocells
Herpes looks like…
Multinucleated together with intranuclear inclusions
Adenovirus looks like…
Slightly enlarged cells with a basophilic, large intranuclear inclusion
Primary TB infection is characterized by
Necrotizing granulomas
Define Gohn complex
Pulmonary granuloma + hilar lymph nodes
Secondary TB (often) involves…
Lung apex
Miliary TB involves…
Disseminated disease: granulomas all over the place (can be primary or secondary)
Histological appearance of necrotizing granulomas
Giant cells/lymphocytes surround necrotizing center, neutrophils outside of this
Mycobacteria (stain)
Acid-fast organisms –> stain red
Mycobacterium avium occurs in which two situations
- HIV/Immunocompromised with granulomas or mycobacterial pseudotumor; 2. Right middle lobe syndrome in small, old ladies, bronchiectasis of right middle lobe secondary to poor clearance of secretions
Describe histoplasma identification. What does histo look like grossly?
Small, unequal budding (bowling pins), silver stain; necrotizing granuloma similar to TB
Coccidiodomycosis identification
Large organisms with thick walled spherules, silver/PAS/H&E staining
Blastomycosis identification. Special clinical presentation? Special histological presentation?
Single based broad bud; presents w/ skin disease; large granulomas with necrosis that contains neutrophils
Aspergillus identification
Hyphae, narrow angle branching, septate; large organism
Invasive aspergillus looks like what?
Bulls-eye parttern (target lesion)
T/F: Cryptococcus can occur in healthy people
True
What other presentation do we worry about with crypto?
Meningitis
Cryptococcus identification
Halo due to mucoid capsule: stain w/ mucoid stains (can also use silver stain), narrow-base buddings
Pneumocystis identification (hint: what does it do to the alveolar spaces?)
Fills alvealor spaces with pink, foamy material and must use silver stain; dense rim w/ dot in middle and DO NOT BUD
