HISTOPATHOLOGIC STUDY OF HANSEN'S DISEASE

Histopathologic Study of Hansen's Disease. Ramesh Dhakhwa, Samir Majagaiyan, Sailesh Pradhan. BJHS 2021;6(3)16. 1606-1610. Introduc on Hansen's disease is a chronic infec ous disease caused by Mycobacterium leprae. Accurate clinical and histopathological diagnosis forms the backbone for appropriate treatment and preven ng deformi es and drug resistance. Several studies have been conducted on clinical presenta on of leprosy however there is a paucity of leprosy related histopathological data from Nepal.


Introduc on
Hansen's disease is a chronic infec ous disease caused by Mycobacterium leprae. Accurate clinical and histopathological diagnosis forms the backbone for appropriate treatment and preven ng deformi es and drug resistance. Several studies have been conducted on clinical presenta on of leprosy however there is a paucity of leprosy related histopathological data from Nepal.

Objec ves
The objec ves of this study were to evaluate histopathological features of leprosy in skin biopsies, categorize them into various types based on Ridley Jopling classifica on and to correlate them with clinical presenta ons.

Methodology
Ninety six skin biopsies histologically diagnosed cases of th leprosy from 16 October 2020 to 15th April 2021 were included in the study. Ethical consent was taken from the Ins tu onal Review Commi ee of Kathmandu Medical College Public Limited (Ref.: 011020202005). Hematoxylin and Eosin stain was used to study histopathological details. Wade-Fite stain was used to evaluate Bacillary index. The lesions were classified as per the Ridley-Jopling classifica on. Histopathologic findings were correlated with clinical diagnosis.

INTRODUCTION
Hansen's disease or leprosy is one of the leading causes of physical disabili es, which contribute to intense social s gma resul ng in discrimina on of pa ents and their families, especially in low-economic communi es. It is a chronic infec ous disease caused by Mycobacterium leprae, principally affec ng the cooler parts of the body, mainly skin and peripheral nerves; it also involves muscles, eyes, bones, 1 tes s and internal organs. The causa ve agent of leprosy, M. leprae, was discovered in 1873 by Armauer Hansen. Even though it was discovered early, it has not been cultured as 2 yet. Leprosy is an important public health problem in most of the developing countries including Nepal. Prevalence of leprosy in Nepal was reported to be 0.99/10,000 popula on in 2017/18 according to sta s cs of Department of health 3,4 services (DoHS) Nepal. The clinical manifesta ons of leprosy are so diverse and can mimic a variety of unrelated diseases. Presenta on may vary from an insignificant skin 5 lesion to extensive disease. Lack of accurate diagnosis and treatment of leprosy can cause permanent damage to skin, 6 nerves, limbs and eyes leading to deformi es. In most of the cases, diagnosis of leprosy is based on different clinical parameters which involve detailed examina on of skin 7 lesion and peripheral nerve and skin smear examina on. In some early and borderline cases of leprosy, it is difficult to diagnose only on clinical basis, hence histopathological examina on is a must for confirma on of diagnosis in doub ul cases of leprosy. Clinico-histopathological correla on of [8][9][10][11][12] leprosy assumes a pivotal role for definite diagnosis. Examina on of a biopsy specimen for histopathology can also be valuable to evaluate prognosis of the disease and provide appropriate treatment. It may also help to assess 13,14 regression of the disease in pa ents under treatment. In our ins tu on, skin biopsy is commonly performed in order to confirm the diagnosis of leprosy. However, no study has been done regarding the diversity of histopathologic features. We aim to study the histopathological features of leprosy in skin biopsies and to categorize them into various types based on Ridley Jopling classifica on and to correlate with clinical presenta ons whenever possible. There was a male preponderance with a male: female ra o of 2.3:1 (Fig. 1). Age of the pa ents ranged from 12 to 79 years with most of the cases falling in the third decade of life (39.6%). Skin lesions presented clinically as nodules and papules (31%) and hypoesthe c patches (69%). Most cases of Lepromatous leprosy presented clinically as nodular and papular lesions whereas tuberculoid spectrum of disease presented as hypoesthe c patches. Histopathologic examina on revealed epidermal and dermal changes in skin biopsies. Epidermal changes included presence of atrophy, hyperplasia, spongiosis and acanthosis. Dermal changes noted were presence or absence of Grenz zone, perineural and perivascular lymphocy c infiltrate, granulomas, aggregates of foamy macrophages and mul nucleated giant cells. Perineural lymphocy c infiltrate and granulomas were noted in tuberculoid spectrum of disease whereas Grenz zone and foamy his ocytes were noted in lepromatous spectrum. (Fig. 3-5      is the most widely used classica on system for Leprosy. Histopathologic diagnosis is considered the gold standard for diagnosis. Histomorphologic features considered for the diagnosis and classifica on of leprosy includes epidermal [8][9][10][11][12] and dermal changes.

METHODOLOGY
We conducted a prospec ve study in 96 skin biopsies which were clinically and histopathologically diagnosed as Hansen's disease and classified into various subtypes based on histopathologic features. Our study showed a male predominance with male to female ra o of 2.4:1. Other studies [13][14][15][16] have also reported male preponderance. Increased incidence of Hansen's disease in male could be due to increased chance of contact in males and occupa onal 14 factors. Vasaikar et al however found a higher number of 17 female pa ents with male to female ra o being 0.8:1. Leprosy can occur at any age. Age of the pa ents in our study ranged from 12 to 79 years. Most of the cases were seen in the third decade (39.6%) followed by fourth (14.6%) and second decade (13.5%). Roy et al also reported 16 maximum number of cases in third decade. Kadam et al 18 found most of their cases in 35-55 years age group. Presence of Leprosy in a wide age range points towards the endemic nature of the disease in our community. Moreover increased incidence in a produc ve age group is a ma er of concern for the na on. Hypopigmented patches over skin surface with loss of temperature sense and numbness is a characteris c feature 16 of leprosy. We also observed hypoesthe c lesion as the most common presen ng feature of leprosy (65/96) followed by papules and nodules (31/96). Similar findings were observed in studies done by Manandhar et al and Roy 13,16 et al.
Hypoesthe c patches were more commonly no ced in tuberculoid spectrum of disease which is likely due to increased incidence of nerve damage. The most common subtype of leprosy in our study was borderline tuberculoid BT (31/96) which is in contrast to the studies done by Sinha et al. who reported Borderline Lepromatous BL to be the most frequent type and Kaur et al 6,15 who observed LL to be the commonest type. Manandhar et al and Roy et al have however found BT to be the commonest sub type. This varia on could be due to the regional differences, socioeconomic and immune status of 19 the study popula on. Borderline tuberculoid BT and tuberculoid TT type leprosy typically show nerve oblitera on and erosion with infiltra on of neurovascular bundles and sweat glands. Diagnosis of Lepromatous spectrum of Leprosy is rela vely easy. Lepromatous leprosy LL type showed typically presence of grenz zone and aggregates of foamy his ocytes in the dermis with high Bacillary Index (4+ to 6+). In our study, poorly formed granulomas were observed in Borderline Leprosy (BL). Bacilli were readily demonstrable with Bacillary Index ranging from 3+ to 6+. Epidermal changes were variable ranging from atrophy, hypertrophy, spongiosis and non specific changes in both tuberculoid and lepromatous spectrum and were not of much help in classifying into subtypes. In midborderline (BB) leprosy, macrophages are uniformly ac vated to epithelioid cells but are not localized in to dis nct granulomas, and lymphocytes are scanty. There are 21 no Langhan's giant cells. BI ranges from 3 to 4. In our study also there were presence of ill defined granulomas in mid borderline (BB) leprosy. BI however ranged from 1 to 3. The term indeterminate leprosy is used to describe pa ents presen ng with very early leprosy lesions that cannot be categorized definitely along the immunopathologic 21 spectrum (eg; cannot be determined as BT or LL). In our study we came across three cases where there were mild lymphocy c and macrophage accumula on around neurovascular bundles. No well formed granulomas were seen. Bacilli could not be iden fied, however clinical features were sugges ve of leprosy. Hence a presump ve diagnosis of IL was made. Clinicohistopathologic correla on of Hansen's disease is 22 challenging especially in early lesions.
In our study the overall clinicohistological correla on was 39.58% only and highest correla on was observed in LL (75%) and lowest in BL(27.78%). Twenty six cases were clinically diagnosed as Hansen's disease only without any clinical classifica on and were not counted for correla on. Clinicohistologic correla on showed a wide varia on ranging from 33 to 81% in various studies (Table 3) Table 3: Clinico-histopathological correla on by different authors.
This may be due to several factors like different criteria used to select the cases, number of cases of each type, age of the lesion, nature and depth of the biopsy, quality of the sec on, number of acid-fast stained sec ons examined, immunological and treatment status of the pa ent at the me of diagnosis, retrospec ve and prospec ve studies etc. There is also a possibility of inter observer bias both clinically 26 and histopathologically. Nadkarmi et al found the highest clinicohistological correla on (81.8%) taking into 24 considera on a larger sample size of 2640 cases. Our study is limited by a small number of cases in a single ins tute for a