Stains used in amyloidosis-

The histologic diagnosis of amyloid is based almost entirely on its staining characteristics. The most commonly used staining technique uses the dye Congo red, which under ordinary light impas a pink or red color to amyloid deposits. Under polarized light the Congo red-stained amyloid shows so- called apple-green birefringence . This reaction is shared by all forms of amyloid and is caused by the crossed b-pleated configuration of amyloid fibrils. Confirmation can be obtained by electron microscopy, which reveals amorphous nonoriented thin fibrils. AA, AL, and ATTR types of amyloid also can be distinguished from one another by specific immunohistochemical staining. Robbins 9 th edition page no. 156