An evaluation of current methods for the diagnostic histochemistry of amyloid

Six current histological methods for demonstrating amyloid (crystal violet, thioflavine-T fluorescence, Congo-red staining and fluorescence, Sirius-red staining, and Congo- or Sirius-red birefringence) were applied in 25 cases of amyloidosis of various types and 47 pseudo-amyloid lesions. The results were compared and were correlated with those of ancillary histochemical tests and clinico-pathological data and each method's sensitivity and specificity for amyloid was evaluated. Thioflavine-T and, to a lesser degree, Congo-red fluorescence and Sirius-red staining proved very sensitive but not specific. Green birefringence with Congo or Sirius red was specific but not completely sensitive. The coexistence of Congo-red (and Sirius-red) staining and a positive DMAB-nitrite reaction occurred in all amyloid specimens and appeared specific for amyloid.