The Use of Histopathology in Leprosy Diagnosis and Research

Abstract

THE USE OF HISTOPATHOLOGY IN LEPROSY DIAGNOSIS AND RESEARCH The way we think and talk about leprosy, using the terms 'tuberculoid' and 'lepromatous', is histopathologically orientated. In the most widely used system of leprosy classification-the Ridley-Jopling classification-histology plays the major role.' In clinical practice, there is no doubt that the histological assessment by an experienced pathologist of a representative skin (and/or nerve) biopsy and enumeration of bacilli provides information as significant as that derived from the clinical examination of a patient. Only a small proportion of the estimated 10+ million patients with leprosy have been biopsied. The current uses of tissue biopsy fa ll into two broad categories: diagnosis of leprosy and leprosy reactions; and research into inflammatory processes. Some aspects, particularly those with practical applications, are discussed here. Diagnosis of leprosy-early disease Early diagnosis of leprosy is a prerequisite for control as well as for effective therapy. Epidemiologically, the total number of cases of leprosy needs to be established for a region, and much underestimation may ensue from the poor detection of early cases. There is no independent 'gold standard' for the diagnosis of leprosy. Neither serological nor skin tests have sensitivity and specificity high enough to be useful in confirming or eliminating all suspect cases of leprosy. How useful is histopathology? The two cardinal histological fe atures of leprosy are appropriate patterns of inflammation involving certain sites in skin (e.g. nerves), and the demonstration of acid-fast baciUi (AFB) in appropriate sites. The degree of confidence that individual pathologists place in a diagnosis of early leprosy is variable. The importance of accurate histological assessment is emphasized by the widespread poor performance of slit-skin smear bacteriology: low densities of AFB in skin are underestimated or missed entirely, so that cases are missed as well as being misclassified.2 Only one systematic study has been published on the performance of pathologists on leprosy. Three experienced histopathologists examined the same 143 skin biopsies from leprosy suspects in Malawi, where 95% ofleprosy is paucibacillary.3 The results appear disturbing. The proportions of biopsies classed as showing strong or definite evidence of leprosy ranged from 39% to 58%. The proportions of biopsies thought to be 'possibly leprosy' ranged from 11•5% to 38'5%, reflecting an unexpectedly large variation in degree of uncertainty. Nonetheless, considering only the 82 cases that were clinically thought certain to be leprosy, the histopathologists did agree in 63% to 83% of cases.4 Much of the discrepancy in diagnostic certainty derived from differences in the interpretation of nerve involvement by granulomatous or nongranulomatous inflammation. AFB were uncommonly detected in the biopsies from this population.

A Clinico-Pathological Correlation Study of Leprosy in a Tertiary Care Teaching Institute in Northwest Punjab, India

“…Pathological examination not only helps in confirmation of the diagnosis but also helps in exact typing of the disease. [9,10] A reliable diagnosis hinges around a good histopathological diagnosis and demonstration of acid fast bacilli(AFB) in histopathological sections. [10,11] Modified Fite's procedure has proved to be the most valuable in demonstrating leprae bacilli in tissues sections.…”

“…[9,10] A reliable diagnosis hinges around a good histopathological diagnosis and demonstration of acid fast bacilli(AFB) in histopathological sections. [10,11] Modified Fite's procedure has proved to be the most valuable in demonstrating leprae bacilli in tissues sections. [12] Due to its clinical diversity as well as its ability to mimic other diseases, leprosy is sometimes difficult to diagnose clinically, making histopathological examination a helpful diagnostic tool to confirm the diagnosis.…”

Spectrum of Leprosy Patients with Clinico-Histopathological Correlation: A Hospital Based Study

“…5 The study of pathological changes in leprosy help in understanding of disease, complications and its exact typing. 6 Diagnosis of leprosy must be joint efforts of dermatologist, microbiologist and pathologist. Leprosy can be diagnosed by various methods including detail clinical examination of the skin lesions and peripheral nerves, 7,8 demonstration of the Acid Fast Bacilli (AFB) in slit skin smears by Ziehl-Neelsen staining, 9 Histopathological section, 6,10 demonstration of bacilli by modified Fite-Ferraco procedure 11 , and Fine Needle Aspiration Cytology (FNAC) of skin and nerves.…”

“…6 Diagnosis of leprosy must be joint efforts of dermatologist, microbiologist and pathologist. Leprosy can be diagnosed by various methods including detail clinical examination of the skin lesions and peripheral nerves, 7,8 demonstration of the Acid Fast Bacilli (AFB) in slit skin smears by Ziehl-Neelsen staining, 9 Histopathological section, 6,10 demonstration of bacilli by modified Fite-Ferraco procedure 11 , and Fine Needle Aspiration Cytology (FNAC) of skin and nerves. 12 Histopathological examination of skin provides confirmatory information in suspected case and gives indication of progression and regression of disease under treatment.…”

Histopathological Study of Skin Biopsies from Clinically Diagnosed Leprosy Patients – 1 yr Institutional Study

“…Hence histopathological examination of skin biopsies is important in leprosy patients to know the type of leprosy 8 . Exact categorisation of leprosy is important for management of patients 12,14 . Early treatment of patients is important to decrease the bacillary load and also to prevent physical disabilities occurring in leprosy patients.…”