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Exposure to external environmental stimuli can lead to skin aging, pigmentation, hair loss, and various immune-mediated as well as connective tissue diseases. Although conventional treatments are routinely used and favoured, they fail to achieve an adequate balance between clinical and cosmetic outcomes. Exosomes are vesicles with a lipid bilayer released by several cell types. These bioactive vesicles play a crucial role in intercellular communication and in several other physiological and pathological processes. They serve as vehicles for bioactive substances including lipids, nucleic acids, and proteins, making them appealing as cell-free treatments. According to studies, exosomes play a vital role in preventing scarring, and senescence, and promoting wound healing. Moreover, research on the biology of exosomes is growing, which has enabled the creation of specific guidelines and quality control methodologies to support their potential implementation in the future. In this review, we have mainly focused on the role of exosomes in various dermatological diseases, their clinical applications, and the potential for further research pertaining to this.

Background: Atopic dermatitis (AD) has a complex etiology that includes Th2 polarization, which is accompanied by the cytokines IL4, IL-5, IL-13, and IL-31, as well as Th17 and Th22, and in chronic lesions, Th1 cells. Tofacitinib inhibits Th1-, Th2-, and Th17-associated cytokines by selectively blocking JAK1 and JAK3 receptors. We conducted a multicentric, retrospective chart analysis to study the efficacy and safety of tofacitinib in patients with moderate to severe refractory AD. Materials and Methods: We included 16 adult patients (aged >18 years) with moderate to severe AD who had previously undergone systemic therapy with inadequate response. In the baseline, demographic data, previous treatment history, severity scores (eczema area and severity index [EASI] and SCORing Atopic Dermatitis [SCORAD]), and quality of life score (Dermatology Life Quality Index [DLQI]) were noted. Baseline blood investigations, including complete blood count, liver function test, renal function test, lipid profile, and interferon gamma release assay for tuberculosis, were done. Patients were followed up every month for 6 months that included documentation of severity scores, blood investigations, and DLQI. Any adverse events, if reported, were noted. Result: All 16 patients completed the 6-month trial. Our patients were previously treated with cyclosporine (n = 10), methotrexate (n = 3), or both (n = 3). The mean EASI scores improved from 23.38 ± 9.56 at baseline to 8.50 ± 7.57 at the end of 6 months. The mean SCORAD score improved from 41.25 ± 8.69 at baseline to 14.93 ± 7.82 at the end of 6 months. Quality of life also improved as the mean DLQI improved from 15.18 ± 2.73 at baseline to 5.31 ± 4.11 at the end of the study period. No severe adverse reactions were noted, but 3 patients experienced dyslipidemia and 2 patients had altered bleeding time. Conclusion: Tofacitinib is a safe and effective treatment option for recalcitrant moderate to severe adult AD.

Introduction: The treatment options for chronic spontaneous urticaria (CSU) primarily include second generation non-sedative antihistamine (SGAHs). Bilastine is a newer, nonsedating SGAH approved for urticaria in February 2019 by the Drugs Controller General of India. Its major advantages are in terms of superior efficacy, lack of drug interactions and adverse effects, including sedation, compared to conventional SGAHs. The role of cytokines in the pathogenesis of CSU is well known. However, there is a shortage of data regarding the change in serum levels of proinflammatory cytokines following H1 antihistamines. We conducted this trial to evaluate the role of bilastine in cytokine modulation and autoimmunity, thereby explaining its role in modifying the disease process in CSU. Materials and Methods: This prospective study was conducted in a tertiary institute in Kolkata on patients aged 12 years and above with a CSU >6 months. These patients had an unsatisfactory response, as per the Urticaria Activity Score 7 (UAS7), to previous antihistamine therapies in standard doses. Treatment effectiveness was determined by comparing the UAS7 at baseline with that at weeks 4, 8 and 12. Also, baseline serum interleukin-6 (IL-6) and IL-17 were compared with those at the end of the study, that is, 12 weeks. Results: Thirty patients who matched the inclusion criteria and signed informed consent were included in the study. At the end of 12 weeks, 10% of patients (n = 3) achieved a complete treatment response (UAS = 0), whereas 43.33% of patients (n = 13) were labelled as having well-controlled urticaria (UAS

Psoriasis is a chronic inflammatory skin condition affecting millions of individuals worldwide. Over the years, various treatment modalities have been explored to alleviate the symptoms and improve the quality of life for patients with psoriasis. Among these treatment options, lasers and lights have emerged as promising non-invasive approaches with significant efficacy. This review aims to provide an overview of the current understanding and clinical applications of lasers and lights in the management of psoriasis. We have discussed the mechanisms of action behind different laser and light therapies and their impact on psoriatic plaques. Additionally, we discuss the various types of lasers and lights utilized, including excimer lasers, pulsed dye lasers, and narrowband ultraviolet B (NB-UVB) phototherapy, highlighting their unique properties and clinical outcomes. Moreover, we have addressed important considerations related to patient selection, treatment protocols, and potential side effects associated with lasers and lights. We emphasize the need for proper evaluation, monitoring, and customization of treatment plans to ensure optimal outcomes and minimize adverse events.

Pattern recognition receptors (PRRs), which are found in microorganisms but not in hosts, allow Leprae bacilli to be recognized as foreign. Several kinds of pattern recognition receptors, such as toll-like receptors (TLRs), NOD-like receptors (NLRs) and RIG-1-like receptors (RLRs), are present in the innate immune system. Sen and Baltimore (1986) discovered the transcription factor nuclear factor kappa-B (NF-B), employed by eukaryotic cells to regulate immunity, cell differentiation and proliferation. This study aimed to evaluate the role of the nuclear factor kappa B (NF-B) pathway in controlling the cytokine cascade in leprosy due to a lack of understanding of the link between cytokines and the severity of leprosy. Clinically suspected Hansen’s patients were analysed for 4 years. Newly diagnosed leprosy patients were considered to have leprosy disease control (LDC). The cases with active or new lesions and an increase in BI by at least 2+, 12 months after completion of MDT were considered leprosy disease relapse (LDR) cases. Age- and sex-matched healthy individuals served as our control group (HC). An ELISA was performed to measure the concentration of five human cytokines. By qRT-PCR, the quantitative expression of receptor genes (NOD1 and NOD2), cytokine genes and the expression of the transcription factor NFκβ were evaluated. This was followed by a transcription factor NFκβ assay to see its expression in the monocytes of study subjects. Nuclear factor NF-κβ was found to have a pronounced response in monocytes of HC and LDC patients and LDR cases when treated with NOD1 and NOD2 ligands. Our study concludes that the NF-kB pathway is involved in the induction and regulation of the cytokine cascade that contributes to chronic inflammation in leprosy.

Introduction: Vitiligo is a multifactorial disorder, most often explained by the autoimmune hypothesis. The objective of this study is to measure the levels of cytokines IL-6, TNF-α, and IFN-γ in the blood and skin (lesional and uninvolved) of vitiligo patients and to compare it with that of age-matched controls. Methods: IL-6, TNF-alpha, and IFN-gamma cytokines were measured with a BioRad 6110 ELISA reader. We compared the levels of these cytokines in generalized versus localized vitiligo and stable versus unstable vitiligo. We also correlated cytokine levels in blood/lesion/uninvolved skin with body surface area (BSA) involvement and Vitiligo Disease Activity (VIDA) scoring. Result: Forty-three participants, each with vitiligo and control, were analyzed. The values of TNF-α and IL 6 in sera were significantly higher in the vitiligo group compared with the controls (p < 0.001), whereas INF-γ was significantly lower in the vitiligo group than the control group. TNF-α, INF-γ levels when compared between blood, lesional skin, and normal skin in all vitiligo patients were found to be significant (p < 0.001). Conclusion: We conclude vitiligo is strongly associated with increased levels of TNF-α and IL 6.

Introduction: Second-generation H1-antihistamines (SGAHs) are the mainstay of treatment of chronic spontaneous urticaria (CSU). Bilastine, newer non-sedating SGAHs, was recently introduced in India after the approval of the Drugs Controller General of India. There is a paucity of evidence about the long-term efficacy and safety of Bilastine in Indian patients. We undertook this study to find the long-term efficacy and tolerability of Bilastine in patients with CSU in India. Materials and Methods: This retrospective chart analysis was conducted by analyzing electronic medical records from May 1, 2019, to March 20, 2020, to identify patients of CSU who were prescribed Bilastine. Adult patients, with CSU >6 months were included, who had an unsatisfactory response as per Urticaria Activity Score 7 (UAS7) to previous antihistamine therapies, and who continued treatment for at least 6 months were included. Treatment effectiveness was determined by retrospectively reviewing their UAS7 scores from their medical records and evaluating their scores at weeks 4, 8, 12, 16, 20, and 24. Also, DLQI was assessed and compared at baseline and week 24. Result: Forty-nine patients were found to fulfill the criteria and included in the study. At the end of 24 weeks, 51% of patients (n = 25) achieved complete treatment response (UAS = 0), whereas 49% of patients (n = 24) were labeled as well-controlled urticaria (UAS

Several biologic agents have been approved for use in dermatology and other disciplines of medicine. However, based on the mechanism of action and a track record of the response, these agents are being increasingly used for off-label purposes to garner control of more remote and difficult disease processes. Herein, we present three difficult to treat patients where innovative uses of biologics beyond their approved indications have yielded good responses. Our first patient was a case of bullous pemphigoid, who showed excellent response to omalizumab. The second case was a patient of lepromatous leprosy with tenosynovitis and erythema nodosum leprosum, who was treated effectively with infliximab. Our third case was a treatment-resistant pyoderma gangrenosum, where infliximab showed a very good response. In the present study, we report the cases to highlight the usefulness of biologics that can expand much beyond the routine FDA approved indications.

Introduction: Psoriasis is an immune-mediated inflammatory skin disorder, which follows a chronic course. Apremilast is a novel phosphodiesterase 4 (PDE4) inhibitor, approved by US-FDA for the treatment of moderate to severe plaque psoriasis and psoriatic arthritis. A majority of the data related to the effectivity and safety of apremilast use in psoriasis is extracted from clinical trials. The present study was planned to get an insight into real-world experience with the use of apremilast in patients with moderate-to-severe plaque psoriasis related to its effectiveness and safety in India. Materials and Methods: The present study was a retrospective one, wherein a review of the medical records of patients with psoriasis was conducted at one center in Kolkata, who were prescribed apremilast for 16 weeks in a community dermatology practice, from December 2017 to May 2018. Results: Out of 39 patients, two patients discontinued treatment due to diarrhea. Only three patients were treatment naïve; the rest had taken some form of systemic therapy before apremilast. At the end of 16 weeks of treatment with apremilast, PASI 100 was achieved in one patient (2.7%), PASI 90 in one (2.7%), PASI 75 in 18 patients (48%), while 14 patients (38%) achieved PASI 50. Eighteen (46%) experienced adverse events, diarrhea being the most common (29.7%). Conclusion: The findings of the present study indicate that apremilast is effective in a real-world setting, as compared with clinical trials in achieving certain endpoints like PASI 75, as was found in other real-world studies in other countries, as well.

Artificial intelligence (AI) has emerged as a major frontier in computer science research. Although AI has been available for some time and found its application in many fields of medicine, its use in dermatology is comparatively new and limited. A sound understanding of the concepts of AI is essential for dermatologists as skin conditions with their abundant clinical and dermatoscopic data and images can potentially be the next big thing in the application of AI in medicine. There are already a number of artificial intelligence studies focusing on skin disorders, such as skin cancer, psoriasis, atopic dermatitis and onychomycosis. This article presents an overview of AI and new developments relevant to dermatology, examining both its current applications and future potential.

Background: Leprosy is a chronic infectious disease caused by Mycobacterium leprae affecting the skin, peripheral nervous system, and other tissues. The disease is associated with social stigma, and the patients sometimes suffer social discrimination because it often leads to visible physical deformities. Hence, leprosy may have severe impact on the quality of life (QoL) of patients. Aims and Objectives: The aim of this study was to assess the effect of leprosy on the QoL of the affected patients and to find out whether there is some association with certain demographic and clinical factors. Materials and Methods: The Dermatology Life Quality Index (DLQI) questionnaire was used to assess the QoL of 114 patients with leprosy who attended dermatology outpatient department of a tertiary care center of eastern India. This was a cross-sectional study. Results: Among a total of 114 patients, leprosy had no impact on the QoL of 15 (13.16%) patients. There was a mild impact in 23 (20.18%) of the patients. There was moderate impact in 37 (32.46%) of the patients. The disease had severe impact in the QoL of 39 (34.21%) patients. None of the patients had a very severe impact. Several of the clinical aspects such as nerve involvement, systemic features, deformity, disability grade, and type of leprosy have significant impact on QoL. Among the demographic factors, gender had some effects on QoL. Conclusion: Leprosy adversely affects the QoL of those affected. Although it is considered a social disease, at least in our part of the country, demographics have minimal effect on the QoL. Rather, important clinical aspects such as systemic features, nerve involvement, reaction, deformity, and disability have profound impact on the QoL of the patients.

Background: Atopic dermatitis (AD) is a common and chronic, pruritic inflammatory skin condition that affects all age groups. There was a dearth of consensus document on AD for Indian practitioners. This article aims to provide an evidence-based consensus statement for the management of AD with a special reference to the Indian context. This guideline includes updated definition, etiological factors, classification, and management of atopic dermatitis. Methodology: The preparation of guidelines was done in multiple phases. Indian Dermatology Expert Board Members (DEBM), recommended by the Skin Allergy Society of India, prepared 26 evidence-based recommendations for AD. An extensive literature search was done in MEDLINE, Google scholar, Cochrane, and other resources. Articles published in the past 10 years were reviewed and recommendations were graded based on the quality of evidence as per GRADE. After forming the initial structure, DEBM met in Mumbai and gave their decisions on an agree and disagree scale with an Indian perspective. Finally, their suggestions were compiled for preparing the article. After DEBM finalized the draft, a treatment algorithm was formulated for the management of AD. Results: DEBM suggested a working definition for AD. The panel agreed that moisturizers should be used as mainstay of therapy and should be continued in all lines of therapy and in maintenance phase. Topical corticosteroids and topical calcineurin inhibitors should be considered as the first line of treatment. Among systemic therapies, cyclosporin should be considered first line, followed by azathioprine, methotrexate, and mycophenolate mofetil. Phototherapy can be an effecive alternative. Empirical food restriction was recommended against. Conclusion: These guidelines should form a reference for the management of patients with AD in an evidence-based manner.

Introduction: Primary cutaneous amyloidosis (PCA) can be classified into four principal categories: macular amyloidosis, lichen amyloidosis, biphasic, and nodular amyloidosis. Some unusual variants such as widespread diffuse hyperpigmentation without papules, poikiloderma like involvement, lesions following Blaschko's line, etc., have also been reported. However, not much data are available regarding the demography, epidemiology, clinical patterns, and distribution and histopathological findings, especially from the eastern part of India. Aims: We conducted a cross-sectional, institution-based study to evaluate clinicopathological pattern and factors of PCA in eastern India. Materials and Methods: We recorded clinical and histopathological findings of 100 consecutive patients of PCA presenting to a tertiary care institution of Kolkata in eastern India. Results: We found female patients of PCA outnumber male (M:F =1:1.9) with majority of patients being young adults (56%) between 20 and 40 years of age. More than half (54%) of the patients were pruritic. The severity of pruritus is significantly more associated with lichenoid and biphasic variants over macular amyloidosis. Positive family history was recorded in 17% of cases. Macular variant was the most common variant constituting 48% of the total PCA. We also found that the association with history of friction and scrubbing and photo-exposure were statistically insignificant. However, duration of the disease has statistically significant association with the disease morphology. Congo red stain showed these deposits as reddish orange substance in 28 patients out of 64 patients' samples on which Congo red could be performed. Conclusion: Our study revealed that many concepts of pathogenesis of PCA including friction and photoexposure might have lesser importance. However, morphological types were significantly associated with the duration of the disease and symptom severity.

Drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome, is also known as drug induced hypersensitivity syndrome and by various other names. It is now recognised as one of the severe cutaneous adverse reaction (SCAR) and can be potentially life-threatening. Historically, it was most frequently linked with phenytoin and was initially described as phenytoin hypersensitivity syndrome. However, it was later found to be caused by various other medications. Anticonvulsants and sulfonamides are the most common offender. Characteristically DRESS has a latent period of 2 to 6 weeks. The pathophysiology remains incompletely understood but involves reactivation of viruses and activation of lymphocyte. It is manifested most commonly with a morbilliform cutaneous eruption with fever and lymphadenopathy. The severity of this syndrome is related to the systemic involvement, which can result in multi-organ failure. Most important step in the management of DRESS is early diagnosis and immediate cessation of the suspected offending drug. Patients of DRESS syndrome should be managed in an intensive care set up for appropriate supportive care and infection control. Topical corticosteroids can give symptomatic relief, but systemic therapy with steroid and other immunosuppressant is usually required.

Introduction: Mycobacterium leprae has a small genome and a tendency of persisting as a very low-grade infection. The authors have shown earlier, that the changes in TTC repeats, in M. leprae genome may contribute to the restriction of the pathogenicity of the bacterium and its survival strategy in case of pure neural Hansen's disease. We suspect, that a similar genomic reduction if happens in treated cases of Hansen's disease, can be a determining factor for developing persisters and relapse. Aim: The present study aimed to find out if there was any evidence of genomic reduction in treated cases of Hansen's disease that showed microbiological nonresponse. Methods: Skin biopsies were taken from treated cases of Hansen's disease at tertiary centers in Kolkata and at Raipur who had bacterial index (BI) unchanged or increased compared to their pretreatment BI. Analysis for the mutation in rpoB gene and folP1 gene were done to rule out rifampicin and dapsone resistance, respectively. The entire TTC repeat region of the bacteria was amplified by polymerase chain reaction and was subjected to sequencing. The obtained sequences were then analyzed by CLUSTALW. Results: A total of 127 patients were included in the study of which in 52 the BI remained same and 75 had an increase in BI, even after 6 months of completion of multidrug therapy. Among the samples, 2 had positive rpoB gene mutation. No mutation was found in the folP1 gene. The TTC repeat of both the rpoB-resistant samples was found to have 17 copies, which matched their pretreatment copy number. In other 125 cases, 60 cases showed no change from their pretreatment TTC number. Of those 65 samples that showed evidence of genomic reduction, 11 samples showed one copy, 41 showed 2 copies, and 13 showed 3 copies deletion. We also observed a significant regional variation. Conclusion: We concluded that there was evidence of genomic reduction, which might lead to microbiological nonresponse in treated cases of Hansen's disease. This indicated a possibility of future persistence and relapse.

Acute generalised exanthematous pustulosis (AGEP) is a severe cutaneous adverse reaction and is attributed to drugs in more than 90% of cases. It is a rare disease, with an estimated incidence of 1–5 patients per million per year. The clinical manifestations characterised by the rapid development of sterile pustular lesions, fever and leucocytosis. Number of drugs has been reported to be associated with AGEP, most common being the antibiotics. Histopathologically there is intraepidermal pustules and papillary dermal oedema with neutrophilic and eosinophilic infiltrations. Systemic involvement can be present in more severe cases. Early diagnosis with withdrawal of the causative drug is the most important step in the management. Treatment includes supportive care, prevention of antibiotics and use of a potent topical steroid.

Some cutaneous adverse drug reactions (CADRs) are severe life-threatening conditions due to multisystem involvements with a high morbidity and mortality rates ranging from 25 - 70% and require immediate medical care. But there are huge controversies regarding the management because large clinical trials are lacking. Most frequent discussion and division occur regarding the use of systemic corticosteroid as early intervention with corticosteroids controls inflammation. Corticosteroids are potent agents that target several intracellular processes to modify almost all components of inflammatory and immune responses but their impact on the long term disease course is not known. Controlled relapses of rash and hepatitis may occur as corticosteroids are tapered. A chronic HHV6 activation promoted by systemic steroids could explain these relapses. Second important issue is the use of antitubercular drugs (ATD) in case of CADR due to multidrug therapy of ATD. As both the tuberculosis and CADR are life threatening conditions and we can not spare treatment of tuberculosis for CADR, we should come to a conclusion which is not yet decided. In the same way the use of antileprotic MDT in CADR due to MDT raises a similar controversy. So, here we focus on those controversies and discuss the issues.

Psoriasis is a chronic immune-mediated inflammatory condition, affecting 2–3% of the population. In recent years, advent of biologics, including secukinumab, have been a major advancement in the management of difficult-to-treat plaque psoriasis. However, high cost of biologics is often a deterrent, especially for Indian socioeconomic condition. Apremilast is an oral phosphodiesterase 4 inhibitor that is safe for use along with many other systemic therapies of psoriasis, including biologics. We report two cases of psoriasis on secukinumab therapy for long duration with good response to therapy. Later, addition of apremilast, allowed halving the dose of secukinumab with maintenance of improvement.

Background: Pure neural leprosy (PNL) still remains a diagnostic challenge because of the absence of sine qua non skin lesions of leprosy and a confirmatory diagnostic method. The authors had earlier described a simple yet objective technique of combining fine needle aspiration cytology (FNAC) coupled with a multiplex polymerase chain reaction (PCR) in a pilot study, wherein the technique showed promise of a reliable diagnostic tool. In the pursuit of further evidence, the authors carried out a 4-year study with PNL cases to find the efficacy and reliability of the said method in a larger sample size. Aim: This study was conducted to find the efficacy, reliability, and reproducibility of FNAC coupled with multiplex PCR and Ziehl-Neelsen (ZN) staining in identifying the cases of PNL. Materials and Methods: All cases that were suspected to be suffering from PNL, following evaluation by two independent observers were included in the study and were subjected to FNAC from the affected nerve, and the aspirates were evaluated for cytology, ZN staining, and multiplex PCR for Mycobacterium leprae genome. In addition, serum anti-PGL1 levels were also performed in all the study subjects. Fifteen non-PNL cases were also included in the control arm. Results: A total of 47 cases were included in the test arm and subjected to FNAC. Conventional ZN staining could demonstrate acid-fast bacilli (AFB) in only 15 out of 47 cases (31.91%) while M. leprae DNA could be elicited in 37 (78.72%) cases by the multiplex PCR. Only 13 (27.65%) out of 47 cases showed anti-PGLI-1 antibody positivity. On cytological examination of the nerve aspirates, only 11 (23.40%) cases showed epithelioid cells whereas nonspecific inflammation was seen in 26 (75.60%) cases. Conclusion: The results of this study conducted over a larger sample size corroborate with the findings of our pilot study. In a resource poor set up, FNAC in combination with ZN staining and multiplex PCR is a rapid, simple, and easily performed test, which can give a reproducible and objective diagnosis in cases of PNL.

One 2-year-old undernourished girl presented to our outpatient with large erythematous scaly plaques in arm along with multiple bony swellings over nose, fingers, left foot, and back for the past 1 year. Apart from skin and bone lesions the girl was also had intermittent fever, pallor, irritability, and malnourishment. Her parents gave a history of incomplete healing at the BCG vaccination site. The case was diagnosed to be case of disseminated mycobacterial infection skin and bone with the help of histopathology, radiological examination, and DNA polymerase chain reaction (PCR). DNA PCR from the skin lesion came positive for mycobacteria tuberculosis complex. The girl was treated with 6 months of standard antitubercular drug treatment with very good improvement not only of her cutaneous and bone changes but also of her general health and growth. We report the case because paucity of similar infection in literature and for greater recognition of potential epidemiological threat.

Therapeutics of autoimmune bullous disease has seen a major shift of focus from more global immunosuppression to targeted immunotherapy. Anti CD 20 monoclonal antibody Rituximab revolutionized the therapeutics of autoimmune bullous disease particularly pemphigus. Though it is still being practiced off-label, evidences in the form of RCT and meta analysis are now available. Other novel anti CD 20 monoclonal antibodies like ofatumumab, veltuzumab, and ocrelizumab, tositumomab or obinutuzumab/GA101 may add to the therapeutic options in coming days. Beyond anti CD 20 monoclonal antibodies other options that show promise at least in select scenario are omalizumab, TNF inhibitors plasmapheresis and intravenous immunoglobulin. The present article will discuss the role of rituximab and other newer therapeutics in the treatment of autoimmune blistering disease, especially pemphigus and suggests their positions in the therapeutic ladder.

Background: Genomic reduction helps obligate intracellular microbes to survive difficult host niches. Adaptation of Mycobacterium leprae in cases of pure neural leprosy (PNL) in the intracellular niche of peripheral nerves can be associated with some gene loss. Recently, a stable but variable number of tandem repefzats (TTC) have been reported in strains of M. leprae. FolP and rpoB genes are the two common mutation sites which deal with the susceptibility of the bacteria to drugs. Aim: We attempted to find if genomic reduction of M. leprae in context of these TTC repeats or mutations in folP1 and rpoB can be the reason for the restriction of M. leprae in the nerves in PNL. Materials and Methods: DNA extracts taken from fine needle aspiration of affected nerves of 24 PNL cases were studied for tandem repeats with 21TTC primer in multiplex-PCR. Mutations were also studied by PCR Amplification of SRDR (Sulphone Resistance Determining Region) of the folP1 and multiple primer PCR amplification refractory mutation system (MARS) of the rpoB. Results: Of the 24 PNL, only 1 patient showed mutation in the rpoB gene and none in the folp1 gene. Studying the mutation in TTC region of the M. leprae gene we found that all the cases have a loss of a few bases in the sequence. Conclusion: We can conclude that there is consistent loss in the bases in the TTC region in all cases of pure neural Hansen and we postulate that it may be an adaptive response of the bacteria to survive host niche resulting in its restriction to peripheral nerves.