Sural nerve biopsy in leprosy patients after varying periods of treatment: histopathological and bacteriological findings on light microscopy.

As part of a larger study of nerve biopsies from leprosy patients in Ethiopia for the presence of muramidase (lysozyme), sections were also examined by light microscopy after staining with hematoxylin and eosin for cellular infiltrate and a modification of the Ziehl-Neelsen stain for leprosy bacilli. The muramidase findings will be reported separately. This paper describes the infiltrative and bacterial findings in a group of 18 patients, including four with nonlepromatous forms of leprosy who were suffering from delayed hypersensitivity reaction at the time of biopsy. The findings were unexpectedly interesting and revealing. Lepromatous and borderline-lepromatous patients all showed endoneurial and perineurial infiltration of considerable extent and, in several instances, bacilli were wide-spread from one end of the biopsy to the other; in two patients, solid-staining bacilli and globi were found, indicating relapse. In all except two of the nonlepromatous patients (mainly borderline-tuberculoid) there was an extensive and severe granulomatous infiltration, and in one case there was marked caseation in the endoneurial zone. Within the limits of the present study, the findings indicate that biopsy of a peripheral nerve, even when it is not obviously associated with a skin lesion, may reveal pathological changes which are greater in degree than those suggested by skin biopsy or clinical examination. These observations in a somewhat heterogeneous group of patients treated for varying periods of time, and in a study which was not prospectively planned, suggest that similar observations in a larger group of untreated and treated patients, including those who have relapsed, may be of value.