Idiopathic Amyloidosis Due to AA Protein: A Report of 2 Cases

Abstract

Two cases of idiopathic amyloidosis are described. AA protein was found to be the major constituent of tissue amyloid in both, based on sensitivity of Congo red birefringence to pretreatment of slides with potassium permanganate and immunoperoxidase staining with a monospecific antiserum. However, an underlying inflammatory, infectious or neoplastic disorder was not identified. The occurrence of AA amyloidosis without clearcut underlying disease is rare, having been described in only thirteen previous instances. Recent clinical series suggest that such cases may have a different course and response to therapy from “primary” amyloidosis due to systemic light chain deposition. Such cases may also underscore the importance of genetic factors in the pathogenesis of AA amyloid and the importance of characterizing the amyloidoses biochemically, as well as clinically. (The J Histotechnol 12:137, 1989.)

Keywords:

• amyloid A
• idiopathic amyloidosis