Mac Kathy, Wu Xiao Juan, Mai Jun, Howlin Kenneth, Suranyi Michael, Yong Jim, Makris Angela
Renal Unit, Liverpool Hospital, Liverpool, NSW, Australia.
Anatomical Pathology Department, Liverpool Hospital, Liverpool, NSW, Australia.
J Clin Pathol. 2017 Jun;70(6):483-487. doi: 10.1136/jclinpath-2016-203905. Epub 2016 Oct 18.
IgG4 disease is rare. However, IgG4 tubulointerstitial nephritis (TIN) is the most common renal manifestation. IgG4 disease is usually associated with elevated serum IgG4 levels and other organ involvement, low-density renal lesions on enhanced CT imaging and immune activation. The incidence of IgG4-TIN may be underestimated, as staining for IgG4 is not routine. This study sought to describe the prevalence of previously undiagnosed IgG4-TIN. Due to the complexity of the diagnosis, we only attempt to look at IgG4-positive plasma cell TIN as a potential indication for IgG4 renal disease.
A retrospective review of native renal biopsies performed between 2002 and 2012 with a primary diagnosis of TIN was selected. Samples for which interstitial nephritis was secondary to a glomerular disease were excluded. The tissues were stained for IgG4 and scored by two blinded observers. Demographic and follow-up details were collected. This study was approved by the local ethics committee.
82 cases of interstitial nephritis from a total of 1238 renal biopsies (2002-2012) were available after staining for further assessment. 12 samples demonstrated staining consistent with the criteria for IgG4-positive plasma cell TIN, of which 3 had mildly positive staining, 7 moderately positive staining and 2 had markedly positive staining. There were no statistically significant differences in the baseline characteristics between the positive and negative staining groups.
A number of cases of IgG4-positive plasma cell TIN were observed histologically that had been previously diagnosed as non-specific chronic TIN. IgG4-positive plasma cell TIN made up 1% of all renal biopsies performed over 10 years and 13% of all biopsies demonstrating TIN not related to glomerular disease. IgG4 staining should be considered routinely in biopsies demonstrating primary TIN.
IgG4 疾病较为罕见。然而，IgG4 肾小管间质性肾炎（TIN）是最常见的肾脏表现形式。IgG4 疾病通常与血清 IgG4 水平升高及其他器官受累、增强 CT 成像上的低密度肾病变和免疫激活相关。由于 IgG4 染色并非常规检查，IgG4-TIN 的发病率可能被低估。本研究旨在描述此前未被诊断出的 IgG4-TIN 的患病率。鉴于诊断的复杂性，我们仅尝试将 IgG4 阳性浆细胞 TIN 视为 IgG4 肾病的潜在指征。
对 2002 年至 2012 年间进行的原发性诊断为 TIN 的肾活检标本进行回顾性研究。排除间质性肾炎继发于肾小球疾病的样本。组织进行 IgG4 染色，并由两名盲法观察者评分。收集人口统计学和随访细节。本研究经当地伦理委员会批准。
在 1238 例肾活检标本（2002 - 2012 年）中，82 例间质肾炎标本经染色后可用于进一步评估。12 个样本的染色符合 IgG4 阳性浆细胞 TIN 的标准，其中 3 个为轻度阳性染色，7 个为中度阳性染色，2 个为明显阳性染色。阳性和阴性染色组的基线特征无统计学显著差异。
组织学观察到一些此前被诊断为非特异性慢性 TIN 的 IgG4 阳性浆细胞 TIN 病例。IgG4 阳性浆细胞 TIN 占 10 年间所有肾活检标本的 1%，占所有显示与肾小球疾病无关的 TIN 活检标本的 13%。对于显示原发性 TIN 的活检标本，应常规考虑进行 IgG4 染色。
