title: S-100 protein in the diagnosis of tuberculoid/borderline tuberculoid leprosy.
abstract: BACKGROUND
  A definitive diagnosis of tuberculoid and borderline tuberculoid leprosy is based on a demonstration of either acid-fast bacilli or nerve elements within the granulomas. On routine hematoxylin and eosin stains, the nerve fibers are not easily identifiable. In this study, we used S-100 protein to highlight the nerve elements and to count their numbers in leprosy and non-leprosy granulomas.
  
  
  METHODS
  Skin biopsy specimens from 15 cases of tuberculoid/borderline tuberculoid leprosy and 14 cases belonging to other granulomatous diseases of the skin were stained with S-100 protein. The surface area of all the biopsies was calculated and the number of nerve bundles stained with S-100 protein were counted in each specimen.
  
  
  RESULTS
  The nerve bundles were 15 per cm 2 in leprosy cases, and 9.2 per cm2 in non-leprosy cases. In addition, the leprosy cases showed longer nerve twigs that were perpendicularly oriented to the skin surface.
  
  
  CONCLUSIONS
  Immunostaining with S-100 facilitated detection of nerve elements in tuberculoid/borderline tuberculoid leprosy. Also, an increased number of nerve elements were found in leprosy granulomas when compared with non-leprosy granulomas (P=<0.05).
authors.affiliation: Department of Pathology, College of Medicine, King Saud University, Abha, Saudi Arabia.
authors.forename: A R
authors.initials: AR
authors.lastname: Khan