Background: Although major progresses have been made in the diagnostic approaches of peripheral neuropathy in past ten years, 25 to 40% of patients remain undiagnosed. Recently, with use of immunohistochemical (IHC) and ultrastructural techniques, the diagnostic yield has enhanced. The aim of this study was to study the diagnostic utility of incorporating myelin stain, antiNeurofilament (NF) immunostain and ultrastructural evaluation in comparison with routine histological stains, to establish an optimal diagnostic protocol for workup of neuropathies. Methods: Thirty four nerve biopsies received from patients with neuropathies were included with relevant clinical and electrophysiological information. In all the cases, nerve biopsy tissue submitted for evaluation was processed for light microscopic (LM), histochemistry using Luxolfast blue (LFB) myelin stain, and IHC using antiNF antibody. In 15 cases, an additional bit was received in saline/3% glutaraldehyde for electron microscopic (EM) examination. Statistical analysis was performed using Epi Info 3.5.3 software (CDC, Atlanta, 2008) for definitive correlation. Results: Overall the diagnostic yield was 46.7% with morphology alone but when combined with LFB stain combined was 73.3% (p<0.05). Combined diagnostic yield of H&E with NF was 17 cases (56.7%) (p>0.05). On evaluating the combined efficacy of LFB, NFIHC and EM in comparison to routine staining using hematoxylin and eosin, it was observed that 21 biopsies (70%) were abnormal of which 10 were missed on routine examination (p<0.05). Conclusion: This study highlights that large number of cases and the spectrum of nerve pathologies that were otherwise missed owing to evaluation by routine histology alone can be diagnosed using a protocol which combines myelin stain, IHC with NF, and at least assessing semithin sections, for optimal workup of nerve biopsies. Since proper evaluation and accurate diagnosis have direct therapeutic and prognostic connotations, it is imperative that diagnostic centres evolve diagnostic protocol combining the above methodologies.

Keywords: Diagnostic Yield; Immunohistochemistry; Nerve Biopsy; Ultrastructure.