Mechanism of nerve destruction in tuberculoid-borderline leprosy: An electron-microscopic study

Abstract

The ultrastructural changes in radial cutaneous nerve biopsies from 3 tuberculoid and 14 tuberculoid-borderline patients were studied. In tuberculoid leprosy the nerve parenchyma was almost entirely replaced by tuberculoid granuloma. In nerves from borderline-tuberculoid leprosy many axons showed segmental demyelination and Wallerian degeneration. The nerve tissue was gradually replaced by proliferating collagen fibrils and inflammatory granulomata. M. leprae were rare and when present they were found in phagolysosomes of Schwann cells and macrophages. Schwann cells were surrounded and occasionally infiltrated by lymphocytes and macrophages. It was suggested that “sensitized Schwann cells” were the target of a hypersensitivity reaction resulting in their degeneration or death which in turn produced segmental demyelination or Wallerian degeneration.