Epidermolysis Bullosa Acquisita Research Articles

Current Knowledge on Nail Involvement in Autoimmune Bullous Disorders

<b><i>Background:</i></b> There are few studies, mainly case reports, on the involvement of the nail unit in autoimmune bullous disorders. <b><i>Summary:</i></b> Nail involvement in autoimmune bullous disorders is a significant clinical phenomenon, marked by a range of manifestations, most often not presenting with blisters like on the skin but rather with alterations of the nail unit such as paronychia, onychomadesis, or onycholysis. This involvement is particularly notable due to the unique immunological features of the nail unit, including the expression of various antigens and the presence of Langerhans cells. Conditions like pemphigus vulgaris, bullous pemphigoid, epidermolysis bullosa acquisita, linear IgA disease, and bullous systemic lupus erythematosus can lead to nail abnormalities. The prevalence of nail manifestations varies according to the disorder, and diagnosis often relies on histopathological and immunofluorescence testing. Nail involvement correlates with disease severity and duration, sometimes serving as a herald sign. Further research is needed to guide therapeutic approaches for nail involvement in autoimmune bullous diseases. <b><i>Key Messages:</i></b> Nail involvement in autoimmune bullous nail disorders may be confusing as there are almost never bullae. One should keep the diagnosis in mind when facing an atypical paronychia.

The pathological function of neutrophils in pemphigoid diseases

Abstract Pemphigoid diseases (PDs) are a group of autoimmune blistering diseases, including bullous pemphigoid, epidermolysis bullosa acquisita, mucous membrane pemphigoid, linear immunoglobulin A disease, and other rare variants. These diseases are characterized by the presence of autoantibodies that target proteins at the dermal-epidermal junction, resulting in the formation of tense blisters and erosions on the skin and/or mucosa. The current therapeutic approaches, such as systemic corticosteroid, are associated with significant adverse effects, highlighting that safer and more effective treatment options are an urgent clinical need. To address this unmet need, a comprehensive understanding of the detailed mechanisms underlying PDs is essential. Based on their histopathological infiltration in pemphigoid lesions, neutrophils have long been implicated as major contributors to the initiation and progression of the diseases. Numerous in vivo and in vitro studies have investigated the role of neutrophils in the pemphigoid pathology, revealing various pathological mechanisms induced by these cells, including the release of neutrophil elastase and matrix metalloproteinase-9, as well as the formation of neutrophil extracellular traps. The present review provides a comprehensive summary and critical evaluation of the current understanding regarding the role of neutrophils in PDs. In addition, it discusses the potential of targeting neutrophil-associated pathways as a novel therapeutic approach for the diseases.

The Need of Differential Diagnosis Between Vulvar Lichen Sclerosus and Autoimmune Dermatoses in Adolescent Girls.

Vulvar lichen sclerosus (VLS) is a chronic inflammatory condition affecting the anogenital region, which can manifest in prepubertal or adolescent patients. The prevailing theories point to autoimmune and genetic factors. The primary symptoms of VLS typically include vulvar itching, discomfort, dysuria, and constipation. Physical examination often reveals a characteristic figure8 pattern, involving the labia minora, clitoral hood, and perianal region. However, these symptoms and the age of onset are nonspecific and require differentiation from autoimmune dermatoses such as bullous diseases, pemphigus diseases, epidermolysis bullosa acquisita, and dermatitis herpetiformis. We performed this study to distinguish VLS from autoimmune dermatoses, and in doing so, uncover the underlying causes of chronic vulvar changes. This knowledge will enable healthcare providers to offer appropriate medical care to affected patients. The study was conducted between July 2020 and February 2021, with a sample of 55 girls aged 2-18years who did not have any systemic diseases. The study group was composed of 20 girls previously diagnosed with vulvar lichen sclerosus, while the control group included 35 girls without VLS. Questionnaires regarding the medical history of the children were completed by their legal guardians. Blood samples were collected and analyzed biochemically to assess human immunoglobulin A (IgA), IgG, and IgM antibodies against various substrates, including the desmosome of stratum spinosum, basement membrane zone, desmoglein 1 (DSG1), desmoglein 3 (DSG3), BP180-NC16A-4X, BP230gC, pemphigoid antigen, collagen type VII NC1, transitional epithelium, gliadin (GAF-3X), endomysium (EMA), and cellular nucleus (ANA). The analysis of the study group revealed that the most commonly observed signs and symptoms included: itching, soreness, burning sensations, and excoriation, as well as erythema or/and pallor of the skin and perineal mucosa. Among the assessed antibodies, only anti-GAF3x antibodies and ANA antibodies were detected. However, the results did not reach statistical significance (p > 0.5).

Rituximab in the Management of Autoimmune Bullous Diseases: A Treatment-Resistant Case Series from a Single Central European Referral Center.

Background and Objectives: Rituximab (RTX) has been the predominant treatment for autoimmune bullous diseases (AIBDs). The objective of this research was to assess the advantages and safety characteristics of RTX treatment in individuals with AIBD. This assessment focused on clinical remission and a reduction in glucocorticosteroid usage, its effect on the titers of autoantibodies targeting desmoglein-1 (DSG-1) and desmoglein-3 (DSG-3), and adverse occurrences during a 12-month follow-up period in a dermatology department within a Central European university context. Materials and Methods: Our case series involved eleven patients, including eight patients with pemphigus vulgaris, two with pemphigus foliaceus, and one with epidermolysis bullosa acquisita. They received a 1 g dose of rituximab, repeated over a two-week interval. Results: The reduction in a prednisone-equivalent dosage after 2, 6, and 12 months following the second RTX infusion was 65.05%, 73.99%, and 76.93%, in that order. The titers of antibodies against DSG-1 exhibited reductions of 43.29%, 75.86%, and 54.02% at 2, 6, and 12 months, respectively. By contrast, the antibody concentrations targeting DSG-3 displayed a decrease of 27.88%, 14.48%, and 5.09% at the corresponding time points. Over the course of the 12-month monitoring period, 18.18% of patients experienced disease relapse, while the remaining individuals achieved either complete or partial remission with minimal or no therapy. Adverse effects were noted in 36.36% of the patient population; they were mild, and no serious adverse effects were reported. Conclusions: RTX represents an efficacious and well-tolerated therapeutic option for the management of AIBD and merits consideration in cases of refractory AIBD. However, further research is imperative to delineate the most optimal dosage, dosing frequency, and total quantity of maintenance infusions required. Additionally, there is a compelling need for studies that explore the impact of RTX on individuals with AIBD who do not exhibit a significant reduction in anti-desmoglein autoantibody levels.

U-serrated and n-serrated patterns in bullous pemphigoid, epidermolysis bullosa acquisita, and bullous lupus: A retrospective observational study

U-serrated and n-serrated patterns in bullous pemphigoid, epidermolysis bullosa acquisita, and bullous lupus: A retrospective observational study

Clinical Features of Paediatric Inflammatory Epidermolysis Bullosa Acquisita: A Case Series Study.

Epidermolysis bullosa acquisita (EBA) rarely develops in childhood. This study retrospectively recruited paediatric patients with EBA (age ≤ 16 years), diagnosed by clinical and histopathological features and results of immunofluorescence, immunoblotting and enzyme-linked immunosorbent assay (ELISA), and reviews their clinical manifestations, histopathology, immunological features, and responses to various treatments. All 7 included patients presented with inflammatory EBA. Among them, 3 had a bullous pemphigoid-like phenotype. Pathologically, in addition to dermal-epidermal blistering, in all patients, the distribution of neutrophils was superficial perivascular or interstitial, or in the dermal papilla. Mixed neutrophils and eosinophils were detected in 2 of the 3 patients with bullous pemphigoid-like phenotypes. In addition to treatment with glucocorticoids, dapsone was administered in 4 patients, while thalidomide and sulfasalazine were administered in 1 patient. All patients responded to the these therapies. Relapse was mainly due to reduction and cessation of glucocorticoids. In conclusion, EBA in childhood may be unique, and thus distinct from its adult counterpart. Specific treatment and follow-up protocols are required for therapy of this rare autoimmune skin disease in children.

Patterns of Periodic Acid–Schiff Staining in Subepidermal Bullous Disorders with Emphasis on Bullous Pemphigoid

Abstract Background: Direct immunofluorescence (DIF) including salt split skin technique is quintessential in the diagnosis of subepidermal bullous disorders. These techniques are expensive and require technical expertise, limiting their diagnostic utility. The property of periodic-acid–Schiff to stain the basement membrane and the patterns produced by it was observed in a cohort of subepidermal bullous disorders, to see if it offers an alternative cost-effective testing method. Materials and Methods: This was a retrospective, observational study conducted in the department of general pathology, in a tertiary care medical center, over a period of 4 years. Only those cases for which paraffin sections, DIF and direct salt split skin immunofluorescence technique were available were included. The levels of anti-bullous pemphigoid (BP) antibodies were collected where available. Results: Of the 21 cases analyzed, 15 were BP, two each of epidermolysis bullosa acquisita (EBA) and lichen planus pemphigoides (LPP), one each of porphyria cutanea tarda (PCT), and bullous systemic lupus erythematosus (SLE). All the cases of BP, LPP and EBA showed a floor pattern of staining with periodic acid–Schiff (PAS) stain. Roof pattern of staining was observed in bullous SLE and PCT. PAS was found to be useful in diagnosing BP, especially in conjunction with an eosinophil rich bulla and anti-BP antibodies. Conclusion: We found that PAS stain could be an adjunct to hematoxylin and eosin stain when the diagnosis of BP is in doubt. However, larger sample size is needed to study its utility in other subepidermal bullous disorders.

Monocyte populations are involved in the pathogenesis of experimental epidermolysis bullosa acquisita.

Monocytes play a significant role in the pathogenesis of most inflammatory diseases, including autoimmune diseases. Herein, different subpopulations of monocytes often play differential, partially antagonistic roles, in the regulation of tissue populations. Pemphigoid diseases constitute a group of autoimmune blistering skin diseases featuring a marked infiltration of the dermis with immune cells, including monocytes. The monocyte subsets infiltrating the skin, however, have largely remained elusive. Monocyte adhesion and recruitment into the inflamed tissues are regulated by chemokine receptors, most prominently by CCR2 and CX3CR1. To delineate the involvement of monocyte populations in autoimmune blistering skin diseases, we spatiotemporally monitored the dynamic spectrum of monocyte populations that infiltrate the inflamed skin using multiphoton intravital imaging and reporter mice for chemokine receptors. Experimental epidermolysis bullosa acquisita (EBA) was induced by injection of anti-murine type VII collagen (amCOLVII) IgG into the Csf1rEGFP-reporter mice, where circulating myeloid cells, such as monocytes and neutrophils, express an EGFP. EGFP+ cells, including neutrophils and monocytes, were present in the skin, immediately after the deposition of the amCOLVII antibody at the dermal-epidermal junction. To investigate the recruitment and involvement of different monocyte-derived cell populations in the disease course further, EBA was induced in CCR2RFP/+-reporter and CX3CR1GFP/+-reporter mice. A comparable distribution of red fluorescent protein (RFP)+ or green fluorescent protein (GFP)+ was found in both diseased mice and their respective controls over time, indicating the similar recruitment of monocytes into the skin following the binding of autoantibodies. Experiments were extended to the CCR2RFP/RFP-deficient and CX3CR1GFP/GFP-deficient mice to determine whether monocyte recruitment and disease severity are compromised in the absence of the receptor. A comparable pattern was seen in the recruitment of monocytes into the skin in both reporter and deficient mice. However, in contrast to similar disease severity between CX3CR1-deficient and reporter mice, CCR2-deficient mice developed significantly less disease than CCR2-reporter mice, as indicated by the percentage of affected area of ears. Collectively, our observations indicate that while CCR2 and CX3CR1 receptors are not involved in the recruitment of monocytes into the skin, CCR2 deficiency is associated with improved disease outcomes in experimental EBA in mice.

Role of Human Leukocyte Antigen Class II in Antibody-Mediated Skin Disorders.

HLA class II molecules are key factors determining susceptibility to autoimmune disorders, and their role in immune-mediated skin conditions such as psoriasis has been extensively investigated. However, there is currently little understanding of their role in antibody-mediated skin diseases such as autoimmune blistering disorders. We researched the available literature using PubMed to narratively review the current knowledge on HLA associations in antibody-mediated blistering skin pathologies. Our results summarized the risk alleles that are identified in the literature, together with certain known protective alleles: in the pemphigus group, alleles HLA-DQB1*0503 and HLA-DRB1*0402 are most commonly associated with disease; in the pemphigoid group, the most studied allele is HLA-DQB1*0301; in epidermolysis bullosa acquisita, few genetic studies are available; in dermatitis herpetiformis, the association with haplotypes HLA-DQ2 and HLA-DQ8 is strongly established; finally, in linear IgA bullous disease, specific HLA alleles may be responsible for pediatric presentations. Our current pathogenic understanding of this group of disorders assigns a key role to predisposing HLA class II alleles that are able to bind disease autoantigens and therefore stimulate antigen-specific autoreactive T cells. The latter engage B lymphocytes that will produce pathogenic autoantibodies. The distribution of HLA alleles and their disease associations are variable across demographics, and an in-depth pathogenetic understanding is needed to support associations between HLA alleles and disease phenotypes. Additionally, in a personalized medicine approach, the identification of HLA alleles associated with the risk of disease may become clinically relevant in identifying susceptible subjects that should avoid exposure to known triggers, such as medication, when possible.

Rare variants of pemphigoid diseases

Pemphigoid diseases comprise aheterogeneous group of subepidermal autoimmune blistering dermatoses characterized by autoantibodies against structural proteins of the dermal-epidermal junction. Recent decades have witnessed asignificant surge in the incidence of these diseases, which, in addition to general aging of the population, can be attributed to the availability of precise diagnostic methods and improved knowledge of the clinical and immunopathological spectrum. While bullous pemphigoid, mucous membrane pemphigoid, and linear IgA disease account for most pemphigoid disorders, less frequent, presumably underdiagnosed variants are increasingly becoming relevant for clinicians. These include epidermolysis bullosa acquisita, anti-p200 pemphigoid, pemphigoid gestationis, lichen planus pemphigoides, and recently defined entities such as IgM pemphigoid and Orf-induced pemphigoid. Accurate characterization and differentiation of these subtypes are not only of diagnostic relevance but may also be associated with therapeutic and prognostic implications for affected individuals. Due to the rarity of these diseases, no controlled prospective clinical trials currently exist, making their diagnosis and therapy challenging.

Retrospective analysis of autoimmune bullous diseases in Middle Franconia.

Autoimmune bullous diseases (AIBDs) are a group of rare cutaneous disorders affecting cornified skin and mucous membranes. They are characterized by tense or flaccid blistering and erosions due to autoantibodies against desmosomal and hemidesmosomal structural proteins of the skin. This group of disorders can be divided into those of pemphigoid and those of pemphigus diseases. If left untreated, these autoimmune diseases can cause serious or even life-threatening complications such as loss of fluid, superinfections or impaired food intake. Due to modern standardized serological assays, the diagnosis of AIBDs can usually be confirmed in combination with their clinical appearance. Whereas for a long time corticosteroids were the major players in the treatment of these diseases, with the approval of rituximab and other immunosuppressive agents, the therapy has increasingly improved. In this study, we aimed to investigate epidemiologic and clinical features as well as diagnostics and therapy of bullous autoimmune diseases in Middle Franconia, a governorate within the German federal state of Bavaria. Patients diagnosed or treated because of a AIBDs between 01.04.2013 and 31.03.2019 at the dermatological department of the university hospital Erlangen were included in this retrospective study (n = 242). Patients were either diagnosed for the first time (n=176) or the diagnosis has been confirmed (n=66) at the department. The respective incidence was calculated among the 176 subjects who had been diagnosed at the center in this period. Data was taken from patient records and analyzed with Microsoft® Excel. The evaluation included the diagnoses of pemphigus vulgaris (PV), pemphigus foliaceus (PF), bullous pemphigoid (BP), mucous membrane pemphigoid (MMP), linear IgA dermatosis (LAD), epidermolysis bullosa acquisita (EBA), and dermatitis herpetiformis (DH). This study shows that the incidence of each AIBDs in Middle Franconia is low and comparable (PV, PF, LAD, EBA) or lower (BP, MMP, DH) than in other studies and regions. BP is the most common newly diagnosed AIBD in Middle Franconia. Due to the chronic and sometimes severe course of AIBDs, repeated in-house treatments are often necessary. To date, mainly topically and systemically applied corticosteroids in combination with immunomodulators are used as first-line therapy.

Involvement of palms and soles in patients with autoimmune bullous diseases: a comparative analysis of a diagnostically relevant localization.

The involvement of palms and soles is variable among disease entities belonging to autoimmune bullous diseases (AIBD). We present our own clinical-laboratory experience concerning presentations of skin lesions on palms and soles in the pemphigus diseases group, pemphigoid diseases group, epidermolysis bullosa acquisita (EBA), and lichen planus pemphigoides (LPP) and discuss the pertinent literature. Lesions on palms and soles were assessed retrospectively on the basis of just photographic archives from the beginning of 2014 to March 2023. We comparatively evaluated 462 Slavic patients with AIBD. Palmoplantar involvement was observed in only 21 patients with AIBD (12 females and 9 males). There was no statistically significant difference between palmoplantar involvement in the pemphigus diseases group compared to the pemphigoid diseases group and no statistically significant difference between the pemphigus diseases group compared to the subepithelial AIBD. Nevertheless, particularly in LPP and EBA, and occasionally in pemphigus diseases and pemphigoid diseases groups of AIBD, localization on palms and soles may be diagnostically important at the clinical level.

C-type lectin receptor expression is a hallmark of neutrophils infiltrating the skin in epidermolysis bullosa acquisita.

Inflammatory epidermolysis bullosa acquisita (EBA) is characterized by a neutrophilic response to anti-type VII collagen (COL7) antibodies resulting in the development of skin inflammation and blistering. The antibody transfer model of EBA closely mirrors this EBA phenotype. To better understand the changes induced in neutrophils upon recruitment from peripheral blood into lesional skin in EBA, we performed single-cell RNA-sequencing of whole blood and skin dissociate to capture minimally perturbed neutrophils and characterize their transcriptome. Through this approach, we identified clear distinctions between circulating activated neutrophils and intradermal neutrophils. Most strikingly, the gene expression of multiple C-type lectin receptors, which have previously been reported to orchestrate host defense against fungi and select bacteria, were markedly dysregulated. After confirming the upregulation of Clec4n, Clec4d, and Clec4e in experimental EBA as well as in lesional skin from patients with inflammatory EBA, we performed functional studies in globally deficient Clec4e-/- and Clec4d-/- mice as well as in neutrophil-specific Clec4n-/- mice. Deficiency in these genes did not reduce disease in the EBA model. Collectively, our results suggest that while the upregulation of Clec4n, Clec4d, and Clec4e is a hallmark of activated dermal neutrophil populations, their individual contribution to the pathogenesis of EBA is dispensable.

Post COVID-19 cutaneous infection caused by Scedoporium apiospermum in a patient with epidermolysis bullosa acquisita

Post COVID-19 cutaneous infection caused by <i>Scedoporium apiospermum</i> in a patient with epidermolysis bullosa acquisita

Luteolin peracetate and gossypolone inhibit immune complex-mediated neutrophil activation in vitro and dermal-epidermal separation in an ex vivo model of epidermolysis bullosa acquisita.

Natural products have been shown to an important source of therapeutics for human disease. In this study, we aimed to identify natural compounds as potential therapeutics for epidermolysis bullosa acquisita (EBA), an autoimmune disease caused by autoantibodies to type VII collagen (COL7). Utilizing an in vitro experimental system, we screened a natural product library composed of 800 pure compounds for their inhibitory effect on COL7-anti-COL7 IgG immune complex (IC)-mediated neutrophil activation and on neutrophil-mediated tissue damage. Three natural compounds, namely luteolin peracetate, gossypol, and gossypolone were capable in inhibiting the IC-induced neutrophil adhesion and oxygen burst in vitro. Furthermore, luteolin peracetate and gossypolone were able to inhibit the anti-COL7 IgG induced dermal-epidermal separation in an ex vivo model for EBA. In summary, this study demonstrates that luteolin peracetate and gossypolone are potential therapeutics for experimental EBA, which deserves further investigation.

44274 Direct immunofluorescence IgG autoantibody subclass analysis as a tool to differentiate between bullous systemic lupus erythematosus and epidermolysis bullosa acquisita

44274 Direct immunofluorescence IgG autoantibody subclass analysis as a tool to differentiate between bullous systemic lupus erythematosus and epidermolysis bullosa acquisita

183 Exploring the role of C5aR2 in neutrophil-driven autoimmune diseases: An often overlooked player in the pathogenesis of epidermolysis bullosa acquisita

183 Exploring the role of C5aR2 in neutrophil-driven autoimmune diseases: An often overlooked player in the pathogenesis of epidermolysis bullosa acquisita

P18 Epidermolysis bullosa acquisita in children: report of three cases

Abstract Epidermolysis bullosa acquisita (EBA) is an acquired, subepidermal blistering skin disease characterized by autoantibodies against type VII collagen, which links the epidermis to the dermis at the dermo-epidermal junction. Clinically, patients have skin fragility and blisters over trauma-prone sites, scarring, milia and onychodystrophy. The diagnosis can be challenging as it shares clinical and histopathological features with other immunobullous diseases. Although exceptionally rare in children, we report three paediatric patients with EBA and variable disease severity. The main clinical features were blisters (n = 3), milia (n = 3), scarring (n = 2), oral erosions (n = 2) and onychodystrophy (n = 1). Histological findings were nonspecific, showing a subepidermal blister with various inflammatory infiltrates. On direct immunofluorescence a bright deposit of IgG was seen, and the antibodies adhered to the dermal side of the salt-split in two cases. ELISA analysis confirmed circulating autoantibodies against type VII collagen in one patient. All received a course of oral corticosteroids alongside steroid-sparing agents such as dapsone, azathioprine and rituximab depending on clinical response and shared favourable prognosis. Early use of topical steroids can help but high-dose oral corticosteroids are often required as well as steroid-sparing agents such as dapsone, methotrexate, azathioprine, ciclosporin, mycophenolate mofetil, cyclophosphamide and rituximab. In our experience, although the treatment approaches have been different, all the patients had favourable outcomes.

Accuracy of serration pattern analysis by direct immunofluorescence in subepidermal autoimmune blistering diseases.

Background Direct immunofluorescence (DIF) is essential for the diagnosis of sub-epidermal immunobullous diseases (SIBD). Bullous pemphigoid (BP), a sub-epidermal immunobullous disease, shows linear IgG and C3 deposition along the dermo-epidermal junction by DIF. However, similar histological and DIF findings are also seen in epidermolysis bullosa acquisita (EBA). High-power examination of antibody deposition by DIF in a "u" or "n" serrated pattern can help differentiate these two entities. Aims/Objectives The aim of this study was to determine the diagnostic accuracy of serration patterns in IgG-mediated sub-epidermal immunobullous disease. Methods All cases of IgG-mediated sub-epidermal immunobullous disease diagnosed over the past 2 years and 9 months period and confirmed serologically, were included. Examination of the serration pattern in DIF was assessed on oil emersion. Salt split skin indirect immunofluorescence (SSS IIF), BP180 enzyme-linked immunosorbent assay (ELISA), profile ELISA and BIOCHIP mosaic were performed, wherever available. Results This study included 74 cases of bullous pemphigoid, eight cases of mucus membrane pemphigoid (MMP) and one case of epidermolysis bullosa acquisita. The characteristic zigzag "n" pattern was visualised in 66 out of 82 cases (80.5%) of the pemphigoid group (BP + MMP); the single epidermolysis bullosa acquisita case showed the "u" serrated pattern. No statistical correlation was seen between serration pattern and BP180 positivity by ELISA (P = 0.05). Limitations The study is limited by the single case of epidermolysis bullosa acquisita (which could be due to rarity of this disease in north Indian population due to genetic variation), lack of detailed serological investigations and immunoblot in all cases. Conclusion Serration pattern analysis is an easy-to-interpret and highly useful technique for characterisation of sub-epidermal immunobullous diseases.

Use of IgG4 Immunohistochemistry as a Diagnostic Tool for Pemphigus

Pemphigus belongs to the group of antibody mediated autoimmune vesiculobullous disease (AIBD) of skin and mucous membranes. Antibodies are directed against the desmosomal adhesion proteins and IgG4 is the predominant subclass. It is a rare disease associated with significant mortality and morbidity. DIF is the gold standard test for AIBD. It requires fresh frozen section which is a major technical issue in most centres. The aim of this research was to study the diagnostic accuracy of IgG4 immunohistochemistry in pemphigus. The study was conducted as a diagnostic test evaluation in a tertiary care hospital. Paraffin blocks of histopathologically diagnosed AIBD were used for doing immunohistochemistry. The findings were compared with DIF findings. Statistical analysis was performed using SPSS, version 20.0. 48 paraffin blocks of AIBD were selected, DIF of all cases were already done from outside centre. There were 21 cases of pemphigus, 25 cases of bullous pemphigoid and one case each of epidermolysis bullosa acquisita and dermatitis herpetiformis. The sensitivity of IgG4 IHC was found to be 85.7%, specificity 96.3%, positive predictive value of 94.7% and negative predictive value 89.7%. So, we conclude that IgG4 IHC done on paraffin sections can be used as a diagnostic tool for pemphigus.