Amyloidosis_ Lecture_Audio_29th Batch- Prof. Bimalka Seneviratne.pptx

Amyloidosis lecture

1. Amyloidosis Prof. Bimalka Seneviratne Consultant Pathologist/ Senior Lecturer

2. Definition Amyloidosis is the term used for a group of diseases characterized by extracellular deposition of fibrillar, proteinaceous substance called amyloid. There are different types of amyloid protein. Hence the biochemical composition is variable.

3. Identification All types of amyloid have similar morphological appearance & staining properties. Routine tissue stain ( H& E)- amyloid appear as amorphous,eosinophilic, hyaline like extracellular deposits. Confirmation- Special stain(congo red) amyloid gives a red colour and shows apple green birefringence on polarising microscopy.

4. Amyloid deposits Congo red stain : amyloid stains red

5. Structure of amyloid Complex structure Amyloid is composed of 2 main types of proteins 95%- fibril protein 5% - non-fibrillar component (P-component)

6. Cont………. Fibril protein- non- branching fibrils, 8-10nm in diameter and has a β -pleated configuration. Non-fibrillar protein- pentagonal or doughnut shaped ( P- component)

7. Confirmation of Amyloid

8. Classification of Amyloidosis Amyloidosis can be divided into 2 major Categories - (a) Systemic amyloidosis (b) Localized amyloidosis

9. Pathogenesis of amyloidosis Stimulus Soluble precursor protein Partial degradation Insoluble fibril protein

10. Main types of Amyloidosis

11. Pathological changes of amyloidosis Kidney Renal involvement is the dominating and most life- threatening feature of systemic amyloidosis. Amyloid deposition occurs on the basement membrane of the glomeruli, mesangium, tubular basement membrane and vessels. Leads to proteinuria & impaired renal functions.

12. Amyloidosis of kidney

13. Spleen Causes moderate to marked splenomegaly Two patterns- sago spleen lardaceous spleen

14. Liver Causes hepatomegaly Amyloid appears first in the space of disse. There is pressure atrophy of adjacent parenchymal cells

15. Liver Amyloid deposits in the liver (histology section – H&E stain)

16. Heart Involved in both localized & systemic amyloidosis Amyloid is deposited sub endocardially and inbetween myocardial fibres Can produce restrictive cardiomyopathy & conduction defects

17. Heart Amyloid deposits in the heart (congo red stain)

18. GIT Can involve any site from the oral cavity to the anal canal. Deposits are usually seen in blood vessels of the submucosa. May give rise to macroglossia, malabsorption, diarrhoea.

19. Macroglossia Amyloidosis of the tongue

20. Brain Amyloid deposits are seen in patient’s with Alzheimer’s disease