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From questions on page 35

1. DESCRIBE THE HISTOLOGICAL FINDINGS (FIGS 1, 2). WHAT OTHER TEST IS REQUIRED TO MAKE THE FINAL DIAGNOSIS?

Paraffin sections from the sural nerve biopsy specimen demonstrated a reduction in nerve fibres and Schwann cells. Congo red staining of the sural nerve specimen and the vitrectomy fluid showed red-green birefringence when viewed under cross-polarised light, confirming the presence of amyloid. (Figure 1a, b, Figure 2). Resin sections showed bands of Bungner, indicating myelinated axon loss (Figure 1c). Teased preparations showed active axonal degeneration without evidence of remyelination (Figure 1d). Electron microscopy of medium sized fascicles showed short, straight, randomly orientated 8 to 10 nm diameter fibrils, near endomysial capillaries and between Schwann cell subunits, causing distortion of cells and focal disruption of the basal laminae (Figure 1e, f). The amyloid deposits stained uniquely and specifically with antibodies to TTR and staining was completely abolished by prior absorption of the antiserum with an excess of …