Staining with Congo Red (CR) is a qualitative method used for the identification of amyloids in vitro and in tissue sections. However, the drawbacks and artefacts obtained when using this dye can be found both in vitro and in vivo.

Congo red is a direct diazo dye used for staining amyloid in tissue sections (Biosci Rep 2019;39:BSR20181415) This organic compound forms complexes with the misfolded proteins deposited in amyloidosis; analysis of the emission spectra from these complexes reveals the optical reactivity under polarized light, described as apple green ...

We present a case in which systemic amyloidosis was suspected; however, biopsies of the bone marrow, an osteosclerotic bone lesion, arterial and venous vessels, and the fat pad were all negative for the diagnostic Congo red stain.

Congo red staining of a bone marrow biopsy specimen demonstrates amyloid deposits in half of the patients with this disorder; a subcutaneous fat aspirate demonstrates amyloid deposits in 80%.

Congo-red highlights the deposits, and under polarization takes on a bright apple-green birefringence (figure 5). There are significant limitations in the special stains for this condition. A positive reaction with this stain is not always readily seen, and …

2023年7月16日 · The biochemical properties that lead to positive staining in Congo Red are poorly understood. It is thought that a properly made, appropriately linear molecule of Congo Red has affinity for the beta pleated sheets that are the common make up of amyloid. Images: Artifacts: Heat from surgical cautery may cause fringe false positive staining

Congo red special stain performed on 10 μm thick sections is gold standard for diagnosis. Amyloid will show red-orange positive staining under non-polarized light. Under polarized light, best viewed in a darkened room, a positive Congo red stain will demonstrate the characteristic “apple green” birefringence.

2019年6月14日 · Congo red, despite having lower sensitivity, is the standard agent used to identify amyloid in tissues. While the apple-green birefringence seen under crossed polarized light is specific for amyloid material, staining with Congo red is technically difficult resulting in inconsistent staining.

2019年1月15日 · Staining with Congo Red (CR) is a qualitative method used for the identification of amyloids in vitro and in tissue sections. However, the drawbacks and artefacts obtained when using this dye can be found both <i>in vitro</i> and <i>in vivo</i> Analysis of scientific data from previous studie …

Lastly, some atypical amyloidosis cases have been reported to be lack of Congo red staining. 9 Nevertheless, electron microscopy can discern amyloid fibrils even in the absence of positive Congo red staining, thus serving as an adjunctive diagnostic approach for suspected cases of amyloidosis that do not yield to traditional Congo red staining ...