DIAGNOSIS OF AMYLOIDOSIS

Q. 1. Using appropriate technical terminology, compare and contrast these sections with their normal counterparts, paying particular attention to the relationship between structure, function and pathology.

a) A comparison of tissue sections taken from kidney

Panel 1: Visualized Under Low-Polarized Light

(kidneyCRhighP)

(kidneyCRlow)

Panel 2. Visualized under High-Polarized light

(kidneyCRhighPpolar)

(kidney_Congo_Red_lowpolar)

The two images on the left panel show kidney tissue sections with amyloid depositions. They both have amorphous depositions in the glomeruli mesangia, which appear birefringent apple-green in color, as visualized in highly plane-polarized light. On contrary, the Congophilic deposits in same tissue-sections appear salmon-pink when visualized under low plane-polarized light. The birefringent apple-green coloration with high amyloid optical density confirms amyloid the presence of amyloid deposits, which indicates amyloidosis. Although the two tissue sections appear in different colorations, the location of amyloid deposits are clearly differentiated with similar structure (form) of the amorphous amyloid deposits.

Picken (2010) points out that, the pathophysiologic occurrence of amyloidosis in kidney tissues is largely systemic. Given that, various systemic amyloid depositions may occur separately away from the the kidney tissues, extra-renal amyloid depositions can be identified through subsequent staging, to establish whether they are systemic or localized. Yamase (n.d) agrees with (Biesbroeck, 2010) that deposition of amyloid fibrils in the glomerular mesagia forms the basis of pathophysiology of renal amyloidosis. Such amyloid depositions may render glomerular filters "leaky to plasma proteins" such as albumin.

Kidney sections with amyloid depositions

In the images shown above, the amyloid depositions occur around the glomerular mesangia, blood vessels' walls and the basement membranes of the glomerular cells. This makes the areas deposited with amyloid to have a "hyaline appearance." However, amyloid deposition does not lead to any cellular response, thus the area deposited with amyloid appear acellular (Yamase, n. d).

b) A comparison of tissue sections taken from liver

Figure 1 CR-stained light microscopy liver with amyloid

Figure 2 CR-stained high polar liver with amyloid

The above liver tissue section have Congophilic deposits, where figure one appear salmon-pink in color when visualized under light microscopy. Conversely, in figure two above, the liver tissue with amyloid deposits shows birefringent apple-green deposits when examined in highly plane-polarized light, confirming positive amyloidosis in the liver section. Although, the appearance of the Congo-stained tissue section differ in terms of visualized color in low and high-polarized light, it is clear that the location and form of the amyloid deposits perfectly map onto each other.

The normal liver below (figure 3) stained with Congo red show uniform absorption of the Congo red dye as opposed to deferential absorption as observed in liver sections deposited with amyloid.

Figure 3: Normal liver section stained with Congo red

Q. 2. Application of Congo Red-staining for the Diagnosis of Amyloidosis

Sen and Basdemir (2003) point out that routine Congo red staining histochemistry is useful in classification and differentiation of renal amyloid deposition that can lead to early diagnosis of amyloidosis. This concurs with Picken (2010) who say that Congo red is rapid technique for diagnosing early amyloidosis, with fair sensitivity.

Picken (2010) observes that, although the Congo red (CR) staining technique provides a quick diagnostic solution to amyloidosis, small deposits of amyloid proteins in thinner sections of the affected tissues and organs have poor clarity in bright microscopic fields. This implies that, the use of the CR staining technique in thin sections cannot be diagnostically conclusive for amyloidosis, and therefore more confirmatory tests may be required. However, to enhance precision in amyloidosis diagnosis, tissue slides stained with CR should be examined under plane-polarized light, where only the appearance of apple-green deposits should be considered positive amyloidosis.

Conversely, misinterpretation of collagen fibers for amyloid deposits is possible during examination of the CR-stained tissue slides (Nilsson, et al., 2010). Picken (2010) points out that, the success of CR-staining for amyloid detection, depend on how well the sample tissue slides are prepared in terms of fixation and CR-staining protocol. Mayo Medical Laboratories (2012) concur with Picken (2010) that a strong polarizing light source, which allows optical rotation of the polarized light, is very important in examining CR-stained tissues for amyloid deposits. To enhance precision of amyloidosis diagnosis, Donini and Linke (2004) emphasize on the use of Congo red fluorescence (CRF). Furthermore, given that CR-staining is not sufficient in quantifying the amyloid deposits effectively, CRF is an effective method for giving digitized tissue images, which can be used for amyloid quantification. Sen, Ertan and Basdemir (2001) observe that, while CR-staining has reduced sensitivity in frozen tissue sections, CRF has high sensitivity in frozen sections.

References

Biesbroeck, L. (2010, January). Amyloidosis, Nodular Localized Cutaneous: Pathophysiology . Retrieved January 12, 2012, from medscape.com: https://emedicine.medscape.com/ article/1102770-overview#a0104

Donini, U. Linke, R. P. (2004). Congo Red Fluorescence Circumvents Pitfalls in Morphometric Quantitation of Amyloid in Tissue Sections. In: Grateau, G., Kyle, R. A. & Skinner, M. Amyloid and Amyloidosis. Canada: Taylor and Francis Group. p82-84.

Mayo medical Laboratories. (2012). Diagnosis and Classification of Amyloidosis. Retrieved January 11, 2012, from mayomedicallaboratories.com: https://www.mayomedicallaboratories.com/articles/hottopics/transcripts/2009/ 2009-12a-amyloidosis/12a-3.html

Nilsson, K. P., Ikenberg, K., Åslund, A., Fransson, S., Konradsson, P., Röcken, C., et al. (2010). Structural Typing of Systemic Amyloidoses by Luminescent-Conjugated Polymer Spectroscopy. Amercan Journal of Pathololgy, 176(2): 563-574. doi: 10.2353/ajpath.2010.080797.

Picken, M. M. (2010). Amyloidosis-Where Are We Now and Where Are We Heading? Arch Pathol Lab Med, 134, 545-551. Retrieved from: https://www.amyloidosissupport.com/ Picken-amyloidosis4.pdf.

Sen, S., & Başdemir, G. (2003). Diagnosis of renal amyloidosis using Congo red fluorescence. Pathology International, 53(8), 534-538. Retrieved from: https://www.ncbi.nlm.nih.gov/pubmed/12895232 .

Sen, S., Ertan, Y. & Basdemir G. (2001). Congo red Fluorescence in Diagnosis of Renal Amyloid Deposits. Retrieved January 11, 2012, from: https://www.turkjpath.org/ summary_en.php3?id=38.

Yamase, H. (n.d). Renal Amyloidosis. Retrieved January 11, 2012, from: https://radiology.uchc.edu/eAtlas/GU/1518.htm.