Tropical medicine rounds: Histopathological study of apparently normal skin of patients with leprosy

Background: Several clinical and laboratory observations point to the possible microscopical affection of normal-looking skin in leprosy. Objective: This study was carried out to verify the microscopical affection of apparently normal-looking skin in different types of leprosy. Patients and methods: The study included 50 patients with different clinical types of leprosy. Biopsies from both skin lesions and normal-looking skin were obtained from each patient and examined for microscopical evidence of leprosy. Results: Microscopical affection of normal-looking skin was detected in 52% of our cases, with higher incidence of affection towards the lepromatous end of the disease. Conclusion: Our findings underscore that the incidence of microscopical affection of normal-looking skin in leprosy is much higher on the lepromatous end of the spectrum of leprosy than on the tuberculoid end; during treatment, the leprosy granulomas may disappear from the normal skin before the clinical lesions. Moreover, the microscopic picture of indeterminate leprosy can be observed in the normal-looking skin of patients with tuberculoid leprosy or lepromatous leprosy, and this description appears not to be confined to the entity known as indeterminate leprosy.