[Amyloidosis--diagnostic difficulties. A case report of localized amyloidosis]

Abstract

Amyloidosis consists of a group of clinical disorders caused by extracellular deposition of insoluble protein fibrils which present beta pleated sheets configuration. Such structure makes fibrils resistant to proteolysis. Amyloidosis can be of acquired or hereditary origin. Amyloid deposits can accumulate in locally (localized amyloidosis) or simultaneously in many organs (systemic amyloidosis). Unclear pathogenesis and varied etiology result in particular diagnostic difficulties. Current article attempts to discuss this problem. Presented clinical case of a patient with the amyloid tumor in nosopharynx and positive staining for amyloid in abdominal fat tissue biopsy serves as an example of the diagnostical proceedings in amyloidosis. Congo red staining and red-green birefringence under cross--polarized light of histological specimens still remains a standard procedure in amyloidosis diagnostics. Such methods, however, do not allow to determine the type of the precursor protein, and thus the type of amyloidosis. Thus immunohistochemical tests constitute the next diagnostic phase. Currently, expanded diagnostic capabilities of SAP scintigraphy and of DNA sequencing (establishing transthyretin and apolipoprotein mutations) are also available. Research is carried out on the usefulness of fluorescence spectroscopy in the diagnosis of secondary amyloidosis. Mass spectrometry is used in combination with two-dimensional gel electrophoresis techique for the analysis of protein profiles.