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Pathology A - General Pathology > [A] 1.59 Tuberculum. Predominantly exudative and predominantly proliferative tuberculosis > Flashcards

[A] 1.59 Tuberculum. Predominantly exudative and predominantly proliferative tuberculosis Flashcards

1
Q

During tuberculosis infection, which specific lesions appear?

A

Tubercles (small granulomas)

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2
Q

Tuberculosis:

  • Phylum
  • Order
  • Suborder
  • Family
  • Genus
A
  • Phylum: Actinobacteria
  • Order: Actinomycetales
  • Suborder: Corynebacterinae
  • Family: Mycobacteriaceae
  • Genus: Mycobacterium
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3
Q

Mycobacterium bovis affects which species?

A
  • Cattle
  • Deer
  • Goat
  • Swine
  • Dog
  • Cat
  • Humans
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4
Q

M. tuberculosis affects which species?

A
  • Cattle
  • Swine
  • Dog
  • Cat
  • Humans
  • Monkeys
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5
Q

M. avium affects which species?

A
  • Cattle
  • Swine
  • Monkeys
  • Birds
  • Sheep
  • Horses
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6
Q

Mycobacterium under the microscope

A
  • Acid & alcohol fast coccoid rods
  • Ziehl-Neelsen +
  • Gram +
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7
Q

TB: General bacteriology

A
  • Specific, resistant cell wall
  • Replicates inside macrophages
  • Obligatory pathogens, only in hosts
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8
Q

TB infection: Initial stages

A
  1. Macrophages phagocytose bacteria
  2. Fusion of lysosome & phagosome is blocked
  3. Primary TB - Replication within macrophages

*Three weeks later*

IL-12 activates TH1 response →​ Sensitisation phase

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9
Q

IL-12 is produced by…

A
  • AP cells
  • Toll-like-receptor-2 (TLR2)
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10
Q

TB infection: Sensitisation phase

A
  1. CD4+TH1 cells release IL-2 for further proliferation of T-lymphocytes
  2. Effector phase
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11
Q

TB infection: Effector phase

A

INFγ secretion → Macrophage activation

  • Formation of phagolysosome
  • Expression of NOS
  • Formation of NO
  • Damage of the Mycobacteria

Activated macrophages secrete TNFα & IL-1

  • Fusion of langhans type giant cells
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12
Q

TB infection: Langhans type giant cell fusion causes…

A

Granuloma (tubercle) formation

  • Type IV (delayed) hypersensitivity
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13
Q

TB infection: Summarise the steps

A
  1. Mycobacteria → Macrophages
  2. *3 weeks pass*
  3. IL-12 activates TH1 response
  4. Sensitisation phase
  5. Effector phase
  6. Activated macrophages → TNFα, IL-1
  7. Langhans type giant cells fuse
  8. Granuloma formation
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14
Q

Tubercle formtion can start with which processes?

A

Either:

  • Exsudative process
  • Proliferative process
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15
Q

Tuberculum: Starting with an exsudative process

A
  • Exsudation, infiltration, regressive changes
  • Necrosis of the central & serum infiltrated area
  • Epitheloid cells & Langhans-type giant cells appear
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16
Q

Tuberculum: Starting with a proliferative process

A
  • Proliferation
  • Epitheloid cells, Langhans-type giant cells
  • Epitheloid cells necrotise in the centre of the lesion
17
Q

Both tuberculi starting with exudative and proliferative process both end with a…

A

A similar structure

18
Q

Timeline of events of a TB infection in cattle

A
  1. 7 days: Early lesions - Intraalveolar macrophages, giant cells, neutrophils
  2. 14 days: In the tubercles, central neutrophil aggregates surrounded by epithelioid cells
  3. 21 days: Central necrosis in the tubercles
  4. 35 days: First mineralised lesions
19
Q

Histological structure of the tubercle

A
  • Central coagulative necrosis
  • Karyolysis (Ø Nucleus)
    • Proper vascularisation
    • Calcification
  • Macrophages - Epitheloid cells & Langhans-type giant cells
  • A capsule containing lymphocytes & collagenous connective tissue with fibrocytes
20
Q

Tubercle: Morphology

A
  • Pinhead size, grey-white, shining foci →
  • Necrosis: larger, opaque, yellowish in the centre
  • Surrounded by granulation tissue
  • Calcification in the centre
21
Q

Different tubercle structures formed by TB

A
  • Tuberculous cold abscess (Pyogenic bacteria)
  • Tuberculous caverns (Histolysis followed by discharge via airways)
  • Miliary TB (Multiple millet seed-sized lesions)
  • Ulcers
22
Q

Tuberculosis in birds: Granuloma structure

A

Foreign body type:

  1. Necrotic area is surrounded by foreign body giant cells radially → Palisade formation, Ø Central calcification
  2. Next zone: Histiocytes
  3. Only few lymphocytes
  4. Peripheral connective tissue
23
Q

Tuberculosis in birds: Macroscopic morphology

A
  • Tubercule
  • Resorptive tubercles
  • Tubercloconglomerates
  • Larger nodules
24
Q

Predominantly exudative & proliferative TB: Overview

A

Lack of the Th1-type response: Ø Granuloma formation

  • Ø:
    • Necrosis
    • Calcification
    • Foci (tuberculum)
  • Larger, tumour-like lesions (fibrosarcoma) produced
25
Q

Predominantly exudative & proliferative TB: Stages of development

A
  1. Granulation tissue proliferates
  2. Scattered connective tissue cells + Histiocytes + giant cells in foci →
  3. Tuberculous granulation tissue

If there are only histiocytes + Giant cells → Great cell granulation

26
Q

TB fibrosarcoma: Description

A
  • Greyish
  • Homogenous
  • Infiltrative lesion
  • No sharp demarcation
27
Q

What is shown?

A

Predominantly proliferative tuberculosis in a dog

M. avium subsp. hominissuis

  • Note:
    • Enlarged Peyer’s patches
    • Enlarged mesenteric lymph node
28
Q

Predominantly exudative TB

A

A disadvantage of the higher organism

  • Exudation → Ø Cellular reaction
  • Coagulation & necrosis → Caseation → Demarcation
29
Q

Predominantly exudative TB affects which organs?

A

Those with a loose structure:

  • Lungs
  • Udder
  • Lymph nodes
  • Uterus
  • Kidneys

Pathology A - General Pathology (85 decks)

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