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.
Al-Shenawy HA
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Immunoglobulin and Complement Immunohistochemistry on Paraffin Sections in Autoimmune Bullous Diseases: A Systematic Review and Meta-analysis.
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.
Kasperkiewicz M
，Lai O
，Kim G
，DeClerck B
，Woodley DT
，Zillikens D
，Recke A
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Direct immunofluorescence (DIF) versus immunohistochemical (IHC) staining of complements and immunoglobulins (Ig) in pemphigus group.
Pemphigus is a group of bullous disorders of the skin characterized by the formation of autoantibodies present in the intercellular junction of the epidermis. Diagnosis is made by clinical, histopathological examination, and DIF. As DIF needs frozen sections, fluorescent tagged antibodies, UV light microscope for examination, and trained personnel, its non-availability makes a definitive diagnosis challenging.
To evaluate the utility of IHC staining of complements and Ig in cases of Pemphigus.
Twenty-six diagnosed cases of Pemphigus were stained by Peroxidase immunohistochemical method using monoclonal antibody to IgG, IgA, IgM, IgG4, C3, C4 d with DAB as chromogen. Pemphigus cases include twenty of pemphigus vulgaris (PV), four cases of pemphigus foliaceous (PF), and two of pemphigus vegetans (Pveg). Positivity was defined as the deposition of Ig and complements as distinct, continuous brown staining of keratinocytes at intercellular junctions.
On IHC total of 20 PV 17 showed positivity (85%) for IgG, 11 (55%) C4d, 19 (95%) C3d, and 16 (80%) IgG4 deposits at the intercellular junction of the epidermis. All cases of PF showed a deposit of IgG, with three (75%) cases for IgG4, C3d, and C4d. Both cases of Pveg showed positivity for IgG and C4d while one case was negative for IgG4 and C3d. The overall IgG, C3, IgG4, and C4d expression for pemphigus was seen in 88%, 88%, 76.9%, and 61.5% of cases. The relation between these markers, combination of IgG and C3, was best related to each other ( P value = 0.80). The sensitivities for IgG, IgG4, and C3 were 77.8%%, 73%, and 73% resp.
We conclude that IHC is a useful tool in the diagnosis of PV with the highest sensitivity of IgG and C3d. The combination of IgG and C3d could replace the DIF in almost all of our cases, so IHC on FFPE sections be used as an alternative method to DIF.
Rana D
，Khurana N
，Mandal S
，Sahoo BL
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