Histological assessment of dermal nerve damage occurring during multidrug therapy for leprosy

This is a prospective histomorphological assessment of dermal innervation in biopsies taken before and after multidrug therapy (MDT) from 41 leprosy patients: 35 borderline tuberculoid (BT), 3 borderline lepromatous (BL), 3 lepromatous (LL). Biopsies of the same lesions taken before commencement (diagnostic therapy) and at the end of therapy (check biopsy) were compared. Hematoxylin and eosin, immunoperoxidase stain for S-100 protein, and the Holmes' silver impregnation method for nerve cells and fibers were used. Skin biopsies were classified as having detectable or undetectable nerves. Of 35 patients with BT leprosy, 17 had no detectable nerves in their diagnostic biopsies; in the check biopsies of 13 of these 17, dermal nerves remained undetectable, in 2 they were S-100 positive but were Holmes negative. Identifiable dermal nerves were present in diagnostic biopsies from 18 patients; in the check biopsies 5 of these 18 had no detectable nerves while in the remaining 13 nerve branches could be detected. The study provides histological documentation of complete damage to dermal innervation in 62.85% (22/35) of patients with BT leprosy, of which 14.28% (5/35) occurred during MDT. Of the patients with detectable dermal innervation at the onset of MDT, 27.7% (5/18) suffered continuing damage during MDT.