Fig. 4

Endomyocardial biopsy findings. Panoramic view showing replacement type fibrosis (Azan-Mallory, scale bar 500 micron) (a). Congo Red staining was negative without the classical apple-green birefringence under polarized light microscope (Congo Red, scale bar 200 micron) (b). Thioflavin T fluorescence assay was negative (thioflavin T, original magnification ×20) (c). At immunoelectron microscopy, TTR amyloid fibrils are evidenced in the interstitial space (immunoelectron microscopy, scale bar 500 nm) (d)