Reproducibility of histology in leprosy lesions

The variability of three commonly used histological parameters in leprosy histology was examined within and between lesions on individual patients by taking two biopsies, either from opposing edges of the same lesion or from the edge of two separate lesions. There was little variation in granuloma fraction (GF), bacterial index (BI), or histological classification on the Ridley-Jopling scale between biopsies from opposing edges of the same lesion, but there was considerable variation in the GF between biopsies from the edge of different lesions. A lesser degree of variation was seen in the BI between different lesions, and there was little difference in histological classification between established lesions. Thus, it appears that local factors influence the size of the leprosy granuloma, but its histological composition and bacterial load are determined systemically.