[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.

Neuropathological analysis of dementia in a Japanese leprosarium.

In a neuropathological study of consecutive autopsies, prevalence and cause of dementia in a Japanese leprosarium were investigated, where more than 95% of inpatients with a mean age of 70 years are now free from active leprosy. In 10 years (1983-1992), clinically overt dementia at death was 35/136 (25.7%) in the age group over 65 years (mean age 79.4). Autopsy was performed in 85 cases (mean age 81 years), and clinically overt dementia was seen in 25 subjects (29.4%). Neuropathologically, Alzheimer's disease (AD) was seen in 9 cases (10.6%), vascular dementia (VD) in 9 cases (10.6%), mixed type in 3 cases (3.5%) and unclassified in 4 cases (4.7%). In the age group of 65-84 years, AD was 5/58 (8.6%), VD was 4/58 (6.9%), mixed type was 2/58 (3.4%), and unclassified was 1/58 (1.7%). Compared with previous Japanese general population-based data, where VD was more frequent than AD, the rate of dementia in our leprosarium was high, and pathologically confirmed AD was as common as VD. Recently, a prophylactic effect of the antileprosy and anti-inflammatory drug DDS (dapsone, 4,4'-diaminodiphenyl sulfone) has been suggested. Lepromatous patients take more DDS (51.9%) than tuberculoid patients (11.5%), however, as the dementia rate of tuberculoid leprosy (17.9%) in those 65-84 years old is similar to lepromatous leprosy (15.9%) in our study, we do not support their viewpoint.