College of Medicine.
Department of Pathology, Stony Brook University Hospital, Stony Brook, NY.
Adv Anat Pathol. 2022 Mar 1;29(2):97-107. doi: 10.1097/PAP.0000000000000324.
Found in virtually any organ system, immunoglobulin (Ig) G4-related disease (RD) is a recently recognized immune-mediated, systemic, a fibroinflammatory disease characterized histologically by storiform fibrosis, obliterative phlebitis, and lymphoplasmacytic infiltrate with IgG4-positive plasma cells (PCs). IgG4-related Hashimoto thyroiditis (IgG4-RHT), also called IgG4-related thyroiditis, shares many features with IgG4-RD but is distinct in several ways. A case of IgG4-RHT in a 51-year-old African American female is assembled together with a literature review which uncovered 82 cases of IgG4-RHT. The findings and criteria which the respective authors used to reach their diagnoses are analyzed. Findings common to all studies are lymphoplasmacytic infiltration and IgG4-positive staining, while most describe follicular atrophy (95.2%, 79/83). Stromal fibrosis involving >33% of thyroid architecture was reported in 74% (58/78) of cases. While few reports observed storiform fibrosis, all describe lack of obliterative phlebitis or systemic involvement. Discrepancies between reports exist in immunostaining thresholds, as well as grading systems for stromal fibrosis. Based on our review of the literature and experience, we propose a set of best practice recommendations for the diagnosis of IgG4-RHT. Our diagnostic criteria are (1) lack of extrathyroidal IgG4-RD, (2) the fibroinflammatory process should not extend beyond the thyroid capsule, (3) stromal fibrosis comprises at least 30% of the involved tissue, (4) >30% IgG4/IgG ratio, with absolute immunostaining cutoffs varying by the degree of stromal fibrosis: for >50% stromal fibrosis use >20 IgG4+PCs/HPF, for 30% to 50% fibrosis use >30 IgG4+PCs/HPF, (5) fibrosis infiltrates the interlobular/interfollicular space, (6) features of follicle injury, and (7) obliterative phlebitis is not required.
几乎存在于任何器官系统中，免疫球蛋白 (Ig) G4 相关疾病 (RD) 是一种最近才被认识到的免疫介导的系统性纤维炎症性疾病，其组织学特征为席纹状纤维化、闭塞性静脉炎和淋巴浆细胞浸润，伴 IgG4 阳性浆细胞 (PC)。IgG4 相关桥本甲状腺炎 (IgG4-RHT)，也称为 IgG4 相关甲状腺炎，与 IgG4-RD 有许多共同特征，但在几个方面有所不同。本文报道了一例 51 岁非裔美国女性 IgG4-RHT 病例，并进行了文献复习，共发现 82 例 IgG4-RHT 病例。分析了各自作者用于诊断的发现和标准。所有研究都发现淋巴浆细胞浸润和 IgG4 阳性染色，而大多数研究描述滤泡萎缩 (95.2%，79/83)。74% (58/78) 的病例报告有累及>33%甲状腺结构的间质纤维化。虽然少数报道观察到席纹状纤维化，但均描述无闭塞性静脉炎或系统性受累。报道之间在免疫染色阈值以及间质纤维化分级系统方面存在差异。基于我们对文献的回顾和经验，我们提出了一组 IgG4-RHT 诊断的最佳实践建议。我们的诊断标准是：(1) 无甲状腺外 IgG4-RD；(2) 纤维炎症过程不应超出甲状腺包膜；(3) 间质纤维化至少占受累组织的 30%；(4)>30% IgG4/IgG 比值，绝对免疫染色截点因间质纤维化程度而异：>50%间质纤维化使用 >20 IgG4+PCs/HPF，30%至 50%纤维化使用 >30 IgG4+PCs/HPF；(5) 纤维化浸润小叶间/滤泡间空间；(6) 滤泡损伤特征；(7) 无需闭塞性静脉炎。
