Ultrastructural study of the dermal nerves in the cutaneous macular lesions of patients with early leprosy

ABSTRACT

Thirteen biopsies of macular lesions of early leprosy patients were studied ultrastructurally with transmission electron microscopy (TEM). All of the biopsies displayed at least one dermal nerve partially or completely encircled by mononuclear cells in the conventional histopathological study with light microscopy. The patients'diagnosis varied from indeterminate leprosy to borderline tuberculoide (BT). In the ultrastructural study, twenty-seven dermal nerve branches were found in the thirteen biopsies. Twenty dermal nerve branches in eleven biopsies were found to display no inflammatory involvement. Seven nerves in seven biopsies were morphologically associated with mononuclear leukocytic cells. Four biopsies exhibited nerves with and without inflammatory involvement concomitantly. Three nerves showed morphological evidence of endoneurial fibrosis, not morphologically associated with the inflammatory process at least in the sections examined. No detectable axional and Schwann cell ultra strutural changes even in the twenty-seven nerves were found. The sensorial loss exhibited by the patients before the institution of treatment was completely reversed in eight patients after the end of multidrug therapy regimen. These findings suggest that sensory loss in the early stages of leprosy may be caused by reversible pathological mechanisms, rather than anatomical damage. It is also possible, concerning the mechanisms of nerve damage in leprosy, to speculate on the existence of a pathological process which may precede the inflammation.