A19 - Tuberculum. Predominantly exudative and predominantly proliferative tuberculosis Flashcards
What is a tuberculum?
A tuberculum is a clinical manifestation of tuberculosis which conglomerates tubercles into a firm lump, and so can mimic cancer tumors of many types in medical imaging studies
Cellular pathogenesis of a tuberculum:
1. The mycobacterium enters the macrophages, which are not able to kill them Because the bacteria has different molecules which are able to prevent the fusion of the phagosome and the lysosome
2. 3 weeks post infection, the sensitization phase takes place = IL-12 is produced by the Antigen Presenting cells, upong activation of Toll-Like-Receptor 2 and T-Helper cell 1 which is responsible for the cellular immunity
3. Effector phase takes place = The CD4 and the T-helper cell 1 release IL-2 for further proliferation of T-lymphocytes
4. The Inter-Feral gamma secretion causes activation of the macrophages, which have been sleeping for 3 weeks. The macrophages are forced to fuse the phagocytes and the lysosome = Phgaolysosome. The formation of NO leads to the damaginf of the bacteria
5. The activated macrophages, called epitheloid cells, secrete the IL-1, which will actovate the cell and immune system
6. Langhans type giant cells will be developed due to the cytokines forcing the fusion of epitheloid cells
7. There is a granuloma formtation, which can be developed in two ways
The process is a type IV hypersensitivity
Name the developmental ways of a granuloma:
1. Exudative process =
2. Proliferative process =
The outcome is the same !! = tuberculum with the same structure
Time points of the formation of a granuloma:
1. After 7 days: Early lesions and macrophages in the lungs appear
2. After 14 days: Central neutrophils aggregates, which are sorrounded by the epitheloid cells
3. After 21 days: Central necrosis is evident
4. After 35 days: We can already see mineralized lesions, which is calcium deprecation in the necrotized area
Histological structure of the tubercule
IMPORTANT !!!
1. layer: Central cogaluative necrosis
2. layer: We see macrophages: They are called epitheloid cells and langhans type giant cells
3. layer: The capsule. Which containts lymphocytes that shows the secondary adaptive immune response. Collagenous connective tisse surrounds the tubercule formed with fibrocytes predominantly
What is the morphology of the tuberculum?
Can be seen as small grey-ish white, with a small shiny foci. It is dry and might be surorunded by granulation tissue.
Upon healing we might see fibrotic tubercules due to treatment or the immunity. When healed, the tubercules is replaced by connective tissue.
Tuberculous caverns can also happen
What is tuberculous caverns?
When the content of tubercules are emptied into the airways
Tuberculosis in birds
In birds there is a lack of central calcification, so we will never find calcium in the atrial zone.
Zones:
1. Central necrotic zone
2. Rim of foreign body giant cells radially
3. Histiocytes and a few lymphocytes
4. Connective tissue
What is proliferative tuberculosis?
1. Lack of Th1 type response
2. There is no granuloma formation, because there is no central necrosis
3. There is a proliferation of the tubercultic granulation with connective tissue cels, fibroblasts, histiocytes and sometimes giant cells = Tuberculosis granulation tisse
What is exudative tuberculosis?
1. We see severe exudation and necrosis
2. There is fibrinogen and exudate rich in firbrinogen
3. There is a major necrosis, demaracting by tubercuotic tissu
4. typically happens in: Lungs, udder, uterus, kidneys Organs with loose structure
