[A morphological study of nerve biopsies in leprous neuropathy]

Peripheral nerve biopsies from 10 leprosy patients(6 tuberculoid patients and 4 lepromatous patients) were studied morphological aspect. Light microscopical examination showed that the perineurium was markedly thickened by infiltrated cell in tuberculoid type and Mycobacterium leprae in lepromatous type. Schwann cell markedly decreased in number, and nerve fiber disappeared without regeneration in severe cases. In mild cases, subperineurial edema was present. The nerve fiber density was normal or mild decreasing. Ultrastructural examination showed abnormality of basal lamina on perineurial cells. The basal lamina of the perineurium completely disappeared in severe cases, and showed splitting even if the perineurium had normal structure in light microscopy. Both type of leprous neuropathy had same pathological changes in regard to abnormality of the basal lamina. There were many M. leprae presented in Schwann cells, fibroblasts and perineurial cells on the nerve of lepromatous patients, although few M. leprae in the nerve of tuberculoid patients. This study provides that these abnormality of perineurium is characteristic in both types of leprous neuropathy.