Diagnostic value of immunohistochemistry on formalin-fixed, paraffin-embedded skin biopsy specimens for bullous pemphigoid

Utility of C3d and C4d immunohistochemical staining in formalin-fixed skin or mucosal biopsy specimens in diagnosis of bullous pemphigoid and mucous membrane pemphigoid

Bullous pemphigoid (BP) and mucous membrane pemphigoid (MMP) sometimes have overlapping clinical, histopathological, and direct immunofluorescence (DIF) features in the early stages. Complement deposition is an intrinsic component of the patho-mechanism of BP in contrast to MMP. Hence immunohistochemistry (IHC) for C3d and C4d may be helpful in differentiating the two disorders. Seventy-four patients of BP and 18 patients of MMP along with 10 negative controls were enrolled in this study. C3d and C4d IHC was performed in formalin-fixed skin biopsy specimens. C3d IHC staining in BP/MMP had a sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 59.2%/41.2%, 100%/100%, 100%/100%, 25.6%/50.0%, respectively. C4d IHC staining in BP/MMP had a sensitivity, specificity, PPV and NPV of 26.8%/17.6%, 100%/100%, 100%/100% and 16.1%/41.7%, respectively. Receiver operator analysis showed utility of C3d in diagnosing both BP [Area under curve (AUC) = 0.8, p = 0.0001] and MMP (AUC = 0.71; p = 0.001). C4d was useful in diagnosis of BP (AUC = 0.5; p = 0.0001), but not MMP (AUC = 0.6; p = 0.064). Hence, C3d is a better diagnostic modality for BP as compared to C4d, whereas C3d and C4d have lower diagnostic importance in MMP. C3d IHC can be employed in diagnosing BP when a second biopsy for direct immunofluorescence (DIF) is not possible or where a facility for IF microscopy does not exist.

Direct Immunofluorescence of IgG on Formalin-Fixed Paraffin-Embedded Tissue by Heat-Induced Antigen Retrieval as a Sensitive Method for the Diagnosis of Pemphigus

Purpose

Direct immunofluorescence (DIF) on frozen sections (DIF-F) plays a key role in the identification and differential diagnosis of bullous dermatoses, which are a group of critical autoimmune diseases that include pemphigus, bullous pemphigoid (BP), and epidermolysis bullosa acquisita (EBA). However, this technique requires specialized laboratory equipment conditions, sample acquisition and sample preservation. In this study, the application value of DIF on paraffin-embedded tissue sections (DIF-P) detecting IgG using heat-induced antigen retrieval (HIAR) in the diagnosis of bullous dermatosis was explored.

Patients and Methods

Samples from 12 patients with pemphigus vulgaris (PV), 10 patients with pemphigus foliaceus (PF), 17 patients with BP, and 4 patients with EBA were retrospectively studied for DIF-P IgG detection. Formalin-fixed, paraffin-embedded tissue (FFPE) was used, and the antigen retrieval method used in the experiment was HIAR. All patients were diagnosed with the autoimmune bullous disease (AIBD) based on clinical presentation, histopathology, DIF-F, and enzyme-linked immunosorbent assay (ELISA).

Results

Intercellular staining for IgG in the epidermis was successful in paraffin-embedded tissue sections in 11 of 12 PV samples and in all 10 PF samples. IgG at the basement membrane zone (BMZ) was not detected by immunofluorescent staining in 17 BP samples and 4 EBA samples.

Conclusion

The detection of IgG by DIF-P using HIAR can be used for the diagnosis of pemphigus as an alternative method to DIF-F.

Bullous pemphigoid diagnosis: the role of routine formalin-fixed paraffin-embedded skin tissue immunochemistry

The gold standard for diagnosing bullous pemphigoid (BP) is the detection of linear deposition of IgG and/or C3 at the dermoepidermal junction using direct immunofluorescence (DIF). Because DIF has several disadvantages, primarily the requirement for frozen specimens, we assessed the diagnostic value of immunohistochemical (IHC) staining for BP detection. Eighty-eight patients with bullous lesions were included in this study. IHC staining for C3d, C4d, and IgG was performed on 88 samples, which included specimens from patients with DIF-confirmed BP (n = 43), clinicopathologically suspected BP with negative DIF results (n = 9), and other bullous diseases (n = 36). Diagnosis based on positive results for C3d, C4d, or IgG in IHC staining detected 86% of DIF-confirmed BP cases. The sensitivity of IHC staining for the detection of DIF-confirmed BP cases and clinicopathologically suspected BP cases was similar to that of DIF (80.8% vs. 84.3%), but the specificity was higher (83.3% vs. 75.0%). Five of the nine clinicopathologically suspected BP cases were diagnosed using IHC staining. Thus, IHC staining of routine biopsy material could be an alternative method for diagnosing BP. IHC staining has considerable diagnostic potential, especially in cases with a high suspicion of BP, but negative or suboptimal DIF results.Please check and confirm the author names and initials are correct. Author 2: Given name: [Chul Hwan] Family name: [Kim], Author 3: Given name: [Yoo Jin] Family name: [Lee].Checked it.

Immunoglobulin and Complement Immunohistochemistry on Paraffin Sections in Autoimmune Bullous Diseases: A Systematic Review and Meta-analysis

ABSTRACT

Immunohistochemistry (IHC) on formalin-fixed, paraffin-embedded tissue has been proposed as a potential tool in the diagnosis of autoimmune bullous diseases (AIBDs) in lieu of standard direct immunofluorescence (DIF) microscopy. To comprehensively determine the diagnostic accuracy of immunoglobulin and complement IHC for diagnosis of AIBDs, we conducted a systematic review and multivariate Bayesian model-based meta-analysis of the literature. Quality and heterogeneity assessment of studies was performed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) checklist and the I2 index, respectively. Electronic searches using PubMed from April 1964 to July 2020 identified 14 articles meeting predetermined inclusion and exclusion criteria. Median sensitivities with 95% credible intervals in pemphigus and pemphigoid were 0.24 (0.01-0.89) and 0.22 (0.02-0.77) with immunoglobulin G (IgG), 0.77 (0.39-0.95) and 0.25 (0.02-0.85) with IgG4, 0.11 (0.02-0.32) and 0.86 (0.56-0.98) with C3d, and 0.84 (0.56-0.97) and 0.75 (0.37-0.94) with C4d, respectively. Specificities were 1.00 (0.00-1.00) with IgG, 0.98 (0.89-1.00) with IgG4, 0.99 (0.97-1.00) with C3d, and 0.99 (0.97-1.00) with C4d. The risk of bias and heterogeneity among studies was a serious problem, decreasing the level of evidence. Our work suggests that, in selected cases, paraffin-based IHC may be a helpful procedure to screen for AIBDs, especially when specialized laboratories and/or biopsy specimens for DIF do not exist. Nevertheless, more studies with a refined quality design are needed to explore the true usefulness of this diagnostic method in AIBDs.

Immunoglobulin M pemphigoid

BACKGROUND

Pemphigoid diseases are a heterogeneous group of autoimmune blistering disorders characterized by predominant deposition of immunoglobulin G or immunoglobulin A autoantibodies against structural proteins of the dermoepidermal junction (DEJ). Sole linear immunoglobulin M (IgM) deposits at the DEJ in pemphigoid diseases have been observed; however, IgM-specific target antigens have not been identified.

OBJECTIVE

Characterization of patients with IgM pemphigoid.

METHODS

Skin biopsy specimens and sera from IgM-positive patients were assessed using histopathology, direct and indirect immunofluorescence microscopy, enzyme-linked immunosorbent assays, immunoblotting, cryosection assay, complement fixation test, and internalization assays.

RESULTS

Tissue-bound linear IgM deposits along the DEJ and circulating IgM autoantibodies against type XVII collagen (Col17) were detected. These circulating IgM autoantibodies showed no complement activating or blister inducing capacity, but the ability of Col17 internalization ex vivo.

LIMITATIONS

Limited number of patients.

CONCLUSION

This study provides further evidence for the role of IgM autoantibodies in pemphigoid disease and highlights Col17 as a target antigen in IgM pemphigoid.

[Modern diagnostics of autoimmune bullous diseases]

Blisters and erosions of skin and mucous membranes are key features of the clinically heterogeneous group of autoimmune bullous diseases (AIBDs). These can be divided into pemphigoid diseases with autoantibodies against structural proteins of the dermal-epidermal junction, pemphigus diseases with autoantibodies against desmosomal proteins, and dermatitis herpetiformis with autoantibodies against transglutaminases 1 and 2. A differentiation based only on clinical features is often not sufficient. After researching the literature in PubMed, the current diagnostic tools for AIBDs are summarized.AIBD diagnostics are performed using histology, direct and indirect immunofluorescence, as well as ELISA and immunoblotting. For serological diagnosis, the conventional multistep approach or multivariant assays for the analysis of autoantibodies against several target antigens in parallel can be applied. These allow a precise classification of AIBD and therefore a tailored use of different therapeutic regimens, e.g., for bullous pemphigoid or pemphigus foliaceus/vulgaris, as well as identification of disease entities with a known association with neoplasia.Direct immunofluorescence is still the diagnostic mainstay of AIBDs. However, novel serological assays, such as target-antigen-specific ELISA or indirect immunofluorescence systems using BIOCHIP™ mosaic technology, allow serologic diagnosis in most AIBD patients and the exact classification of the disease entity at the molecular level.

Comparison of C3d immunohistochemical staining to enzyme-linked immunosorbent assay and immunofluorescence for diagnosis of bullous pemphigoid

BACKGROUND

Bullous pemphigoid (BP), the most common autoimmune blistering disease, may be diagnostically challenging. Direct immunofluorescence (DIF), indirect immunofluorescence (IIF), enzyme-linked immunosorbent assay (ELISA), and recently, C3d immunohistochemistry (IHC), are used as adjuncts to diagnosis.

OBJECTIVE

To compare C3d IHC to DIF, IIF, and ELISA testing in BP diagnosis.

METHODS

C3d IHC was performed on skin biopsy specimens from 51 patients (27 with BP and 24 with other blistering diseases) and compared to DIF and IIF, with anti-BP180 or anti-BP230 ELISA results used as the gold standard.

RESULTS

We found C3d IHC, DIF, and IIF had similar sensitivity (74.1%, 63.1%, and 70.4%), specificity (95.8%, 100%, and 100%), positive predictive value (95.2%, 100%, and 100%), and negative predictive value (76.7%, 70.6%, and 75%) for BP. Cases with positive C3d IHC, DIF, and IIF had significantly higher anti-BP180 and anti-BP230 by ELISA than cases with negative testing (P < .0001). False-negative IIF results were associated with lower BP230 compared with true-positive results (P = .03).

LIMITATIONS

This was a single-center, retrospective study.

CONCLUSION

Our study compared C3d IHC to DIF and IIF in BP diagnosis, demonstrating C3d IHC on fixed tissue provides similar diagnostic utility to immunofluorescence and ELISA.

Diagnosis of autoimmune bullous diseases

Autoimmune bullous disorders (AIBDs) are a heterogeneous group of rare diseases clinically characterized by erosions and/or blisters on the skin and mucous membranes. AIBDs can be categorized into two groups: pemphigus diseases, characterized by intraepidermal blistering and autoantibodies against desmosomal proteins such as desmoglein (Dsg) 1, Dsg3, members of the plakin family, and subepidermal AIBDs, comprised of pemphigoid diseases and dermatitis herpetiformis. Autoantibodies in dermatitis herpetiformis target transglutaminases 2 and 3, while in pemphigoid disease, autoantibodies are directed against structural proteins of the dermal-epidermal junction. Although analysis of a perilesional biopsy with direct immunofluorescence (IF) microscopy is still the diagnostic gold standard, several assays have become widely available that allow serological diagnosis in the majority of patients. Standard serological diagnosis includes indirect IF on monkey esophagus and salt-split human skin. Assays to further characterize autoantibody specificity include ELISA systems based on recombinant forms of the immunodominant regions of the target antigens as well as multivariant indirect IF microscopy tests with several miniature substrates. These serological assays are complemented by various in-house assays using immunoblotting and ELISA, which are only available in specialized laboratories. Here we review new developments in the diagnosis of AIBDs and describe state-of-the-art diagnostic procedures for this group of diseases.

Diagnostik blasenbildender Autoimmundermatosen

Blasenbildende Autoimmundermatosen (BAIDs) sind eine heterogene Gruppe seltener Erkrankungen, die klinisch durch Erosionen und/oder Blasen an Haut und Schleimhäuten charakterisiert sind. BAIDs können in zwei Gruppen eingeteilt werden: Pemphigus-Erkrankungen, die durch intraepidermale Blasenbildung und Autoantikörper gegen desmosomale Proteine wie Desmoglein (Dsg) 1, Dsg3 und Mitglieder der Plakin-Familie charakterisiert sind, sowie subepidermale BAIDs, die Pemphigoid-Erkrankungen und die Dermatitis herpetiformis umfassen. Bei der Dermatitis herpetiformis greifen die Autoantikörper die Transglutaminasen 2 und 3 an, während sie bei Pemphigoid-Erkrankungen gegen Strukturproteine der dermoepidermalen Junktionszone gerichtet sind. Die Analyse einer periläsionalen Biopsie mittels direkter Immunfluoreszenzmikroskopie (IF-Mikroskopie) stellt zwar nach wie vor den diagnostischen Goldstandard dar, mittlerweile sind jedoch verschiedene Tests allgemein verfügbar, die eine serologische Diagnosefindung für den Großteil der Patienten ermöglichen. Zur serologischen Standarddiagnostik gehört die indirekte IF auf Affenösophagus und NaCl-separierter Spalthaut. Die Spezifität der Autoantikörper kann mit ELISA-Systemen, die auf rekombinanten Formen der immundominanten Regionen der Zielantigene basieren, sowie indirekter IF-Mikroskopie anhand multivarianter Tests mit mehreren multivariate näher charakterisiert werden. Diese serologischen Tests werden durch verschiedene hauseigene Immunoblotting- und ELISA-Systeme ergänzt, die nur in spezialisierten Laboratorien verfügbar sind. In diesem Review geben wir einen Überblick über neue Entwicklungen bei der Diagnose von BAIDs und beschreiben moderne Diagnoseverfahren für diese Krankheitsgruppe.

Immunological methods for the diagnosis of oral mucosal diseases

Immunological methods, which have been widely used in autoimmune blistering diseases (AIBDs) of the oral mucosa, can also be adopted as auxiliary diagnostic tools in oral lichen planus (OLP) and discoid lupus erythematosus (DLE). AIBDs, characterized by autoantibodies against structural proteins of keratinocytes or the basement membrane zone, clinically present as blisters and erosions of the oral mucosa. When atypical lesions occur, OLP or DLE may be confused with AIBDs. The improvement of diagnostic accuracy is necessary due to the significant differences in treatment and prognosis among these diseases. A variety of immunological methods are used for qualitative and quantitative detection of target antigens and autoantibodies. These methods can evaluate efficacy of treatment, monitor diseases and guide treatment decisions. In this review, we discuss the application of immunofluorescence, biochemical tests, and protein microarrays for AIBDs, OLP and DLE, as well as the differential diagnostic methods using immunological tests.

Autoimmune Subepidermal Bullous Diseases of the Skin and Mucosae: Clinical Features, Diagnosis, and Management

Autoimmune subepidermal blistering diseases of the skin and mucosae constitute a large group of sometimes devastating diseases, encompassing bullous pemphigoid, gestational pemphigoid, mucous membrane pemphigoid, epidermolysis bullosa acquisita, and anti-p200 pemphigoid. Their clinical presentation is polymorphic. These autoimmune blistering diseases are associated with autoantibodies that target distinct components of the basement membrane zone of stratified epithelia. These autoantigens represent structural proteins important for maintenance of dermo-epidermal integrity. Bullous pemphigoid (BP) is the most common subepidermal autoimmune blistering disease of the skin and mucosae. Although the disease typically presents with a generalized blistering eruption associated with itch, atypical variants with either localized bullous lesions or "non-bullous" presentations are observed in approximately 20% of patients. A peculiar form of BP typically associated with pregnancy is pemphigoid gestationis. In anti-p200 pemphigoid, patients present with tense blisters on erythematosus or normal skin resembling BP, with a predilection for acral surfaces. These patients have antibodies targeting the 200-kDa basement membrane protein. Epidermolysis bullosa is a rare autoimmune blistering disease associated with autoantibodies against type VII collagen that can have several phenotypes including a classical form mimicking dystrophic epidermolysis bullosa, an inflammatory presentation mimicking BP, or mucous membrane pemphigoid-like lesions. Mucous membrane pemphigoid (MMP) is the term agreed upon by international consensus for an autoimmune blistering disorder, which affects one or more mucous membrane and may involve the skin. The condition involves a number of different autoantigens in the basement membrane zone. It may result in severe complications from scarring, such as blindness and strictures. Diagnosis of these diseases relies on direct immunofluorescence microscopy studies and immunoserological assays. Management of affected patients is often challenging. We will here review the clinical and immunopathological features as well as the pathophysiology of this group of organ-specific autoimmune diseases. Finally, we will discuss the diagnostic approach and the principles of management in clinical practice.

Diagnostic value of autoantibody titres in patients with bullous pemphigoid

BACKGROUND

Bullous pemphigoid (BP) is the most common autoimmune blistering disease of the skin requiring skin and serum tests for a precise diagnosis.

OBJECTIVES

We analysed the sensitivity and specificity of BP-relevant parameters and the value of autoantibody titres during follow-up of BP patients.

MATERIALS & METHODS

In a retrospective single-centre study, we included 200 consecutive patients with BP and 400 non-BP patients, and evaluated the test results of patients' serum and skin. In addition, we followed patients' autoantibody titres and clinical characteristics.

RESULTS

BP180-ELISA revealed the highest sensitivity (85.0%; specificity: 93.9%), while BP230-ELISA demonstrated the lowest sensitivity (55.5%; specificity: 92.9%). Direct and indirect immunofluorescence showed comparable results for sensitivity (77.2%/72.7%) and specificity (94.9%/93.7%). The sensitivity for skin histology was 76.3% (specificity: 81.3%). Longitudinal analysis showed significant changes in autoantibody titres.

CONCLUSIONS

BP diagnostics should include serum tests for BP autoantibodies and skin immunofluorescence. Skin histology is supportive for diagnosis. Autoantibody titres are markers for disease activity.

BP180 Is Critical in the Autoimmunity of Bullous Pemphigoid

Bullous pemphigoid (BP) is by far the most common autoimmune blistering dermatosis that mainly occurs in the elderly. The BP180 is a transmembrane glycoprotein, which is highly immunodominant in BP. The structure and location of BP180 indicate that it is a significant autoantigen and plays a key role in blister formation. Autoantibodies from BP patients react with BP180, which leads to its degradation and this has been regarded as the central event in BP pathogenesis. The consequent blister formation involves the activation of complement-dependent or -independent signals, as well as inflammatory pathways induced by BP180/anti-BP180 autoantibody interaction. As a multi-epitope molecule, BP180 can cause dermal-epidermal separation via combining each epitope with specific immunoglobulin, which also facilitates blister formation. In addition, some inflammatory factors can directly deplete BP180, thereby leading to fragility of the dermal-epidermal junction and blister formation. This review summarizes recent investigations on the role of BP180 in BP pathogenesis to determine the potential targets for the treatment of patients with BP.

Can immunohistochemistry replace immunofluorescence in diagnosis of skin bullous diseases?

Autoimmune bullous diseases are distressing and sometimes risky bullous dermatoses characterized by the presence of antibodies focused against disease-specific target antigens. Recognition of these antibodies using immunofluorescence is used to be the only sure diagnostic method after reviewing the routine histopathological section. Because of many causes that make the using of immunofluorescence difficult, we tried to evaluate the role of immunohistochemistry in diagnosis of these bullous skin diseases; 40 pemphigus cases (30 pemphigus vulgaris and 10 pemphigus foliaceus) and 37 non-pemphigus cases (35 vesiculobullous skin diseases and 2 normal skin). Skin biopsy was obtained for histopathological diagnosis, immunofluorescence study, and immune-histochemical studying for IgG4 and C3d expression. IgG4 was positive in almost all cases of pemphigus vulgaris and most of pemphigus foliaceus and bullous pemphigoides, while all other diseases were negative. C3d expression was positive in almost all bullous pemphigoides and pemphigus gestationis cases, while it was negative in almost all other cases. Sensitivity and specificity of both markers increase by using them in combination in diagnosis of such bullous diseases. IgG4 and C3d immunohistochemistry could replace DIF in almost all of our cases, so before doing DIF, reliable immunohistochemical detection of IgG4 and C3d on formalin-fixed tissue is advised to be done.