Approach to the Diagnosis of Amyloidosis

Abstract

Amyloidosis is heterogeneous group of disorder characterized by extracellular deposition of misfolded insoluble proteinaceous material with cross beta pleated sheet structure leading to organ dysfunction. This disease is rare and indeed heterogeneous, as it may be hereditary (familial amyloidosis), secondary to spectrum of inflammatory conditions (AA amyloidosis) or member of plasma cell neoplasm family (AL amyloidosis). AL amyloidosis is the most common type of amyloid, however, is rarely accompanied by multiple myeloma or other lymphoproliferative disorder. This disparity in its origin and presentation needs to be addressed by exhaustive battery of investigation tools, to arrive at right diagnosis with correct typing. This is of utmost importance in guiding the treating physicians to choose appropriate therapeutic options. This review deals with diagnostic approach to amyloidosis and its various subtypes.

Keywords: AA amyloid; AL amyloid; Amyloidosis; Cross beta pleated; Multiple myeloma; Proteinaceous.

Fig. 1

a H & E staining showing amorphous, extracellular, eosinophilic material (×100). b Congo red stain showing deep pink to red colored perivascular amyloid (×400). c Amyloid deposits showing apple green birefringence under polarized light (×400)

Fig. 2

Electron microscopy picture of randomly-oriented, non-branching amyloid fibrils, 7.5–10 nm in diameter, of indeterminate length

Fig. 3

Diagnostic approach to amyloidosis. *Test for amyloid typing should be chosen depending on availability of tissue and technique