Generic Diagnosis of Amyloid: A Summary of Current Recommendations and the Editor’s Comments on Chapters 13–16

Abstract

This chapter provides a brief summary of recommendations regarding current standards for the generic diagnosis of amyloidosis and outlines practical considerations and advice on the available options. Congo red stain continues to be the generally accepted standard in amyloid detection. It has been recently officially acknowledged that, besides apple-green birefringence, other anomalous colors, yellow or orange, are diagnostic of amyloid. However, successful application of the Congo red stain is dependent on many variables, including: preanalytic steps, technical issues associated with stain performance, and its interpretation, which also requires considerable experience on the part of the observer. All of these factors make the routine use of Congo red stain in general surgical pathology difficult and error-prone. In this chapter, technical issues associated with the Congo red stain and polarization, including the thickness of the sections, are summarized. Advantages and disadvantages of the use of other stains, in particular, Congo red fluorescence and Thioflavin stains, are also discussed. Finally, technical issues associated with the utilization of fat biopsy for amyloid detection and staging are considered. The detection of amyloid in tissue sections, which is considered to be the initial and the most critical step in the management of patients with amyloidosis, is entirely dependent upon the skill of the pathologist. Hence, there is an urgent need to increase the level of expertise applied in the diagnosis of amyloidosis among surgical pathologists and a need to concentrate on early detection.