Pulmonary I Flashcards
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Chronic Inflammation
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Acute Inflammation
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Polymorphonuclear cell (PMN) - Acute inflammation
Neutrophils
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Mononuclear Cells - Chronic Inflammation
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What is a granuloma composed of?
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Th1 cells, B cells on outside, Multinucleated giant cells surrounding necrotic core and persistent antigens
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Granulomatous inflammation
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Granulomatous inflammation
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Normal Alveolar Tissue
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Normal lung histology
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Normal lung histo
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Normal Lung
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Acute Bronchopneumonia
Patchy infiltrates
Typical organisms: Streptococcus pneumoniae, Staphylococcus aureus, Pseudomonas aeruginosa, Hemophilus influenzae, and Klebsiella pneumoniae (among others)
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Acute Bronchopneumonia (lobular)
Areas of tan-yellow consolidation, firmer and more raised than surrounding lung
Remaining lung is dark due to pulmonary congestion
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Acute bronchopneumonia
Higher magnification, pattern of patchy distribution seen
Consolidated areas closely match pattern of lung lobules (“lobular pneumonia”)
Bronchopneumonia is classically hospital acquired.
Typical organisms: S. aureus, Klebsiella, E. coli, Pseudomonas
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Acute Bronchopneumonia
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Acute Bronchopneumonia Histology
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Acute lobar pneumonia
More extensive than bronchopneumonia, all of one lobe is consolidated
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Lobar pneumonia + fibrinous pleuritis
If there’s exudate on the surface, may become empyema
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Lobar pneumonia + fibrinous pleuritis
May result in empyema (collection of pus in pleural space)
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Lobar pneumonia + Gray-white hepatization of lower lobe
Filled with leukocytes
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Lobar pneumonia + gray-white hepatization
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Acute pneumonia
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Acute Bronchopneumonia
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Lobar pneumonia
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Bronchopneumonia
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Lobar pneumonia
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Lobar pneumonia
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Acute lobar pneumonia
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Aspiration pneumonia
Usually mixed infection & right airways more vertical, so more common in R. lung
Contains multinucleated giant cells
Contains neutrophilic exudate and dark blue bacterial colonies suggests aspiration or hematogenous spread of infection to lung. Aspirated material from oral-pharyngeal region has bacterial flora. Hematogenous spread of infection to lungs could occur from septicemia or infective endocarditis involving right side of heart
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Aspiration pneumonia
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Aspiration Pneumonia
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Aspiration Pneumonia
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2 lung abscesses (one in upper, one in lower lobe)
Adjacent areas of tan consolidation w/ bronchopneumonia
Abscess = complication of severe pneumonia, most typically from virulent organisms (S. aureus)
Usually a complication of aspiration, more frequent in R. posterior lung
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Lung Abscess + bronchopneumonia
Several abscesses w/ irregular, rough-surfaced walls seen w/in areas of tan consolidation
If large enough, abscesses will contain liquefied necrotic material & purulent exudate that often results in air-fluid level by chest radiograph in abscess
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Lung Abscess
Purulent exudate has drained following sectioning to reveal abscess cavities
Abscesses can be source for septicemia and difficult to treat
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Lung Abscess
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Lung Abscess
More virulent bacteria and/or more severe pneumonias can be assoc. w/ destruction of lung tissue & hemorrhage
Alveolar walls no longer visible because early abscess formation (also hemorrhage)
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Timeline of Tuberculosis
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Ghon Complex
Small tan-yellow sub-pleural granuloma in mid-lung field on right. In hilum, small yellow-tan granuloma in hilar lymph node next to bronchus (Gohn Complex) - characteristic of primary TB. In most people, granulomatous disease doesn't progress. Over time, decreases in size & can calcify, leaving focal calcified spot on chest radiograph, suggesting remote granulomatous disease.
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Gohn Complex
Closer Gohn Complex. Primary TB is pattern seen with initial infection w/ TB in kids. Reactivation (secondary) TB more common in adults.
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Secondary (reactivation) tuberculosis
Most commonly involves apex of lungs (contain higher O2 content, and mycobacterium is aerobic)
Granulomas have areas of caseous necrosis. This is very extensive granulomatous disease. This pattern of mutliple caseating granlumonas primarily in upper lobes most characteristic of secondary (reactivation) TB. However, fungal granulomas (histoplasmosis, crytococcosis, coccidioidomycosis) can mimic pattern.
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Secondary (Reactivation) Tuberculosis
When there is extensive caseation & granulomas involve larger bronchus, it's possible for much of soft, necrotic center to drain out and leave behind a cavity. Cavitation is typical for large granulomas with TB. Cavitation more common in upper lobes.
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Miliary TB
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Miliary TB
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Miliary TB
When immune response poor or overwhelmed by extensive infection, can see "miliary" pattern because there are many small tan granulomas 2-4 mm scattered throughout lung parenchyma. Called miliary because looks like small millet seeds.
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Miliary TB
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Miliary TB
At closer range, miliary pattern seen throughout lung. Dissemination of infectious agent (M. tuberculosis, fungi) may produce a similar pattern in other organs
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Miliary TB
Low power magnification, multiple granulomas.
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Langhans-type giant cell in granulomatous inflammation
At high magnification, granuloma demonstrates that eptihelioid macrophages elongated with long, pale nuclei and pink cytoplasm. Macrophages organize into committees called giant cells. Typical giant cell for infection = Langhan's cell and has nuclei lined up along one edge of cell (Horseshoe). Process of granulomatous inflammation takes place over months to years.
Granulomas are composed of transformed macrophages (epithelioid cells) along with lymphocytes, occasional PMNs, Plasma cells, and fibroblasts.
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Epithelioid response in granuloma
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Caseous necrosis in TB
Edge of granuloma shown here at high magnification. At upper right is amorphous pink caseous material composed of necrotic elements of granuloma as well as infectious organisms. Area ringed by inflammatory component with epithelioid cells, lymphocytes, and fibroblasts.
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Acid-Fast Bacilli on Ziehl-Neilson Stain
In order to find the mycobacteria in a tissue section, a stain for acid fast bacilli is done (AFB). The mycobacteria stain as red rods (seen here).
Gold standard is a culture, but that could take weeks.
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Fungal abscess
Here is a fungal granuloma. Note the sharply demarcated borders to this granuloma, which give it a discrete, spherical appearance both grossly and radiographically.
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Fungal Hyphae of Aspergillus
Hyphae = mold form with filament structures, branch at 45 degree angles (but not the only fungus that does so)
Has propensity to invade blood vessels
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What is a dimorphic fungus?
Grows usually as mold in environment, but as yeast in the body (often due to bird/bat feces)
2 examples: Coccidioidomycosis (More common in SW) and Histoplasmosis (more common in Midwest)
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Coccidioides immitis spherules
Well-formed granuloma has large Langhans giant cell in center. Two small spherules of Coccidiodes immitis are seen in the giant cell.
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Coccidioides immitis spherules
At high magnification, thick wall of C. immitis spherule is seen in giant cell in center of image. Spherule contains endospores. In nature C. immitis exists in hyphal form with characteristic alternating arthrospores.
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Coccidioides immitis spherules high magnification
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Histoplasma granuloma (calcified)
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Histoplasmosis within macrophages
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What are the differences between acute and chronic inflammation?
* Duration, inflammatory cells, vascular changes, Edema, Fibrosis, Systemic manifestation?
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What is granulomatous inflammation?
What is a granuloma?
Special form of chronic inflammation seen in response to particular organisms (i.e. Mycobacterium tuberculosis & certain fungi)
Granuloma = discrete collectio of epithelioid histiocytes (macrophages) surrounded by a rim of lymphocytes and fibrous tissue. Multinucleated giant cells may also be present.
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What is bronchopneumonia? How does it present?
What organisms cause it?
Patchy consolidation of multiple small areas of lung adjacent to inflamed bronchi and bronchioles ("lobular"). Areas of consolidation appear tan & may be raised.
Organisms: S. pneumoniae, S. aureus, E. coli, Klebsiella, Pseudomonas, Haemophilus
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What is lobar pneumonia? How does it present? What organisms cause it?
Large, confluent areas of consolidation (i.e. entire lobes)
Much less common pattern than bronchopneumonia
Organisms: Streptococcus pneumoniae (pneumococcus) and Klebsiella
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What is the pathophysiology of lobar pneumonia due to pneumococcus?
Inhalation -\> Edema -\> Red hepatization -\> Grey hepatization -\> Resolution
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Compare bronchopneumonia and lobar pneumonia microscopically
Appear similar microscopically. Both characterized by massive infiltration of alveolar spaces by neutrophils, along with proteinaceous material, vascular congestion, and occasionally visible bacterial organisms.
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What is aspiration pneumonia characterized by?
Fairly localized inflammation centered around airways and/or small foci within alveolar tissue
Presence of foreign material in association with foreign body giant cell reaction
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What are 4 complications of pneumonia?
Abscess formation
Empyema: purulent exudates w/in pleural cavity
Organization of exudates with pulmonary fibrosis
Sepsis
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What is an abscess?
Focal area of inflammation & necrosis, typically forming a pus-filled cavity due to parenchymal destruction
* Uncommon complication bacteria (usually anaerobes)
* Abscess may contain liquefied, necrotic material and result in "air-fluid level" on x-rays
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Describe the progression of TB
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Primary TB:
* Usually asymptomatic or mild flu-like illness
* in 95% of cases, immunity halts disease progression
* "Gohn Complex" (parenchymal lung lesion plus nodal involvement)
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Secondary TB:
* 5% develop complications
* Almost always symptomatic (chronic cough, hemoptysis, weight loss, low grade fever, night sweats)
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What is another type of tuberculosis?
Progressive/miliary TB
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Describe the significant microscopic findings in TB
Granulomatous inflammation
1. Necrotizing granulomas with "caseous" necrosis
2. Langhans-type giant cells (multinucleated cells with horseshoe arrangement of nuclei)
3. Acid-fast bacilli
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What are common organisms that cause community-acquired acute pneumonia?
Streptococcus pneumoniae
Haemophilus influenzae
Moraxella catarrhalis
Staphylococcus aureus
Legionella pneumophila
Enterobacteriaceae (Klebsiella pneumoniae) and Pseudomonas spp.
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Organisms that cause community-acquired atypical pneumonia
Mycoplasma pneumoniae
Chlamydia spp
Coxiella burnetti
Viruses: RSV, parainfluenza virus (kids), influenza A/B (adults), adenovirus (military recruits), SARS virus
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Organisms that cause nosocomial pneumonia
Gram negative rods belonging to enterobacteriaceae (Klebsiella, Serratia marcescens, E. coli) & Pseudomonas
Staphylococcus aureus (usually penicillin resistant)
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Organisms that cause aspiration pneumonia
Anaerobic oral flora (Bacteriodes, Prevotella, Fusobacterium, Peptostreptococcus) PLUS aerobic bacteria (S. pneumoniae, S. aureus, H. influenzae, P. aeruginosa)
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Organisms that cause chronic pneumonia
Nocardia
Actinomyces
Granulomatous: Mycobacterium tuberculosis, atypical mycobacteria, Histoplasma capsulatum, Coccidioides immitis, Blastomyces dermatitidis
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Organisms that cause necrotizing pneumonia and lung abscess
Anaerobic bacteria (extremely common) with or w/o mixed aerobic infection
S. aureus, K.pneumoniae, S. pyogenes, type 3 pneumococcus (uncommon)
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Organisms that cause pneumonia in the immunocompromised host
Cytomegalovirus
Pneumocytis carinii
Mycobacterium avium-intracellulare
Invasive aspergillosis
Invasive candidiasis
"Usual" bacterial, viral, and fungal organisms (see other cards)
