Peripheral nerve involvement in leprosy: Quantitative histologic aspects

1. Nerve biopsies in three lepromatous and three dimorphous leprosy patients are reported. Bacilli were found in all three lepromatous nerves, and in one dimorphous nerve. Bacilli were present in cutaneous nerve twigs in all six patients. 2. Myelinated fiber counts were severly reduced in four patients. Large fibers were affected to a greater extent than small fibers. 3. Evidence of widespread segmental demyelination with remyelination was present. Wallerian degeneration was not found. 4. Schwann cell involvement with subsequent segmental demyelination appears to be an important event in the pathogenesis of leprous neuritis.