Department of Medicine (Dermatology), University of Chicago Medical Center, 5841 S Maryland Ave, MC5067, Chicago, IL 60637, USA.
Arch Pathol Lab Med. 2012 Nov;136(11):1402-7. doi: 10.5858/arpa.2011-0425-OA.
Pemphigus is a group of autoimmune vesiculobullous diseases characterized by immunoglobulin G (IgG) antibodies directed against desmosomal adhesion proteins, with IgG4 being the predominant subclass in active diseases. Direct immunofluorescence for IgG performed on fresh-frozen tissue plays a crucial role in diagnosing pemphigus. However, the diagnosis might be hindered when frozen tissue is not available.
To evaluate the usefulness of immunohistochemistry for IgG4 performed on paraffin sections as a diagnostic test for pemphigus.
Eighteen immunofluorescence-proven pemphigus cases (12 pemphigus vulgaris, 6 pemphigus foliaceus) were studied. Four normal skin specimens and 32 nonpemphigus vesiculobullous disease specimens served as controls. Paraffin sections of all cases were examined immunohistochemically for IgG4 expression. Positivity was defined as distinct, condensed, continuous immunoreactivity localized to the intercellular junctions of keratinocytes.
The immunostains were independently evaluated in a masked manner by 3 pathologists, with a 100% interobserver agreement. Nine of 12 pemphigus vulgaris cases (sensitivity 75.0%), and 4 of 6 pemphigus foliaceus cases (sensitivity 66.7%), were positive for IgG4 immunostain. The overall sensitivity was 72.2%. One control specimen (bullous pemphigoid) showed IgG4 positivity (specificity 97.2%). In specimens demonstrating acantholysis, 8 of 10 pemphigus vulgaris cases (sensitivity 80.0%) and 4 of 4 pemphigus foliaceus cases (sensitivity 100.0%) were positive for IgG4. The overall sensitivity for specimens with acantholytic lesions was 85.7%.
Immunohistochemistry for IgG4 provides a reasonably sensitive and highly specific test for diagnosing pemphigus, especially when frozen tissue is not available, and active acantholytic lesions are examined.
天疱疮是一组自身免疫性水疱性疾病，其特征为免疫球蛋白 G（IgG）抗体针对桥粒黏附蛋白，在活动期疾病中 IgG4 是主要亚类。直接免疫荧光法检测新鲜冷冻组织中的 IgG 在天疱疮的诊断中起着至关重要的作用。然而，当没有冷冻组织时，诊断可能会受到阻碍。
评估免疫组织化学法检测石蜡切片 IgG4 作为天疱疮诊断试验的有用性。
研究了 18 例免疫荧光证实的天疱疮病例（12 例寻常性天疱疮，6 例落叶性天疱疮）。4 例正常皮肤标本和 32 例非天疱疮水疱性疾病标本作为对照。所有病例的石蜡切片均进行 IgG4 表达的免疫组织化学检查。阳性定义为角质形成细胞细胞间交界处存在明显、浓缩、连续的免疫反应。
3 位病理学家以盲法独立评估免疫染色，观察者间一致性为 100%。12 例寻常性天疱疮病例中有 9 例（敏感性 75.0%），6 例落叶性天疱疮病例中有 4 例（敏感性 66.7%）的 IgG4 免疫染色阳性。总体敏感性为 72.2%。1 例对照标本（大疱性类天疱疮）显示 IgG4 阳性（特异性 97.2%）。在表现棘层松解的标本中，10 例寻常性天疱疮中有 8 例（敏感性 80.0%），4 例落叶性天疱疮中有 4 例（敏感性 100.0%）的 IgG4 免疫染色阳性。棘层松解病变标本的总体敏感性为 85.7%。
免疫组织化学法检测 IgG4 是一种具有较高敏感性和特异性的诊断天疱疮的检测方法，特别是在无法获得冷冻组织且检查活动期棘层松解病变时。
