Department of Nephrology, Graduate School of Medicine, Kyoto University, 54 Shogoin Kawahara-Cho, Sakyo-Ku, Kyoto, 606-8507, Japan.
Department of Nephrology, Kyoto Katsura Hospital, 17 Yamadahirao-Cho, Nishikyo-Ku, Kyoto, 615-8257, Japan.
BMC Nephrol. 2023 Jul 4;24(1):201. doi: 10.1186/s12882-023-03253-8.
Tubulointerstitial nephritis with IgM-positive plasma cells (IgMPC-TIN) is a newer disease about which there are many unclear points. Glucocorticoid therapy is effective in many cases of IgMPC-TIN; however, relapse during glucocorticoid tapering has been reported. Relapse and its treatment are poorly defined.
Case 1 was a 61-year-old man with renal dysfunction and proteinuria. Tubulointerstitial nephritis and IgM-positive plasma cells were observed in a renal biopsy. He was diagnosed with IgMPC-TIN accompanied by Fanconi syndrome and distal renal tubular acidosis (d-RTA). Prednisolone (PSL; 30 mg daily, 0.45 mg/kg/day) treatment was highly effective, and PSL was gradually tapered and discontinued after 1 year. However, 1 month after PSL discontinuation, therapeutic markers were elevated. Therefore, PSL (10 mg daily, 0.15 mg/kg/day) was administered, and the markers indicated improvement. Case 2 was a 43-year-old woman referred for renal dysfunction and proteinuria. Laboratory data revealed that she had primary biliary cholangitis (PBC), d-RTA, and Fanconi syndrome. A renal biopsy showed accumulation of IgM-positive plasma cells in the tubulointerstitium without any glomerular changes. A diagnosis of IgMPC-TIN was made and the patient was started on PSL (35 mg daily, 0.6 mg/kg/day). Therapeutic markers decreased immediately and PSL was discontinued after 1 year. Three months later, the proteinuria and Fanconi syndrome worsened. PSL treatment was restarted (20 mg daily, 0.35 mg/kg/day) and markers indicated improvement. Case 3 was a 45-year-old woman with renal dysfunction and proteinuria. Tubulointerstitial nephritis and IgM-positive plasma cells were observed in a renal biopsy. The patient had PBC, Sjögren syndrome, d-RTA, and Fanconi syndrome, and the diagnosis of IgMPC-TIN was made. The patient was started on PSL (30 mg daily, 0.4 mg/kg/day) and disease markers decreased immediately. However, when PSL was tapered to 15 mg daily (0.2 mg/kg/day), the patient's serum IgM levels increased; therefore, we maintained the PSL at 15 mg daily (0.2 mg/kg/day).
We report three cases of relapsed IgMPC-TIN associated with reduction or discontinuation of glucocorticoid therapy. In these cases, elevation of serum IgM preceded that of other markers such as urinary β-microglobulin, proteinuria, and glycosuria. We recommend monitoring serum IgM levels while tapering glucocorticoids; a maintenance dose of glucocorticoid should be considered if relapse is suspected or anticipated.
IgM 阳性浆细胞性间质性肾炎（IgMPC-TIN）是一种较新的疾病，有许多方面尚不清楚。糖皮质激素治疗在许多 IgMPC-TIN 病例中有效；然而，已经报道了糖皮质激素减量期间的复发。复发及其治疗方法定义不明确。
病例 1 是一名 61 岁男性，存在肾功能障碍和蛋白尿。肾活检观察到肾小管间质性肾炎和 IgM 阳性浆细胞。他被诊断为 IgMPC-TIN 伴有 Fanconi 综合征和远端肾小管酸中毒（d-RTA）。泼尼松龙（PSL；30mg/天，0.45mg/kg/天）治疗效果显著，1 年后逐渐减少并停用 PSL。然而，PSL 停药 1 个月后，治疗标志物升高。因此，给予 PSL（10mg/天，0.15mg/kg/天）治疗，标志物显示改善。病例 2 是一名 43 岁女性，因肾功能障碍和蛋白尿就诊。实验室数据显示她患有原发性胆汁性胆管炎（PBC）、d-RTA 和 Fanconi 综合征。肾活检显示肾小管间质性 IgM 阳性浆细胞堆积，无肾小球改变。诊断为 IgMPC-TIN，并开始给予 PSL（35mg/天，0.6mg/kg/天）治疗。治疗标志物立即下降，1 年后停用 PSL。3 个月后，蛋白尿和 Fanconi 综合征恶化。重新开始 PSL 治疗（20mg/天，0.35mg/kg/天），标志物显示改善。病例 3 是一名 45 岁女性，存在肾功能障碍和蛋白尿。肾活检观察到肾小管间质性肾炎和 IgM 阳性浆细胞。该患者患有 PBC、干燥综合征、d-RTA 和 Fanconi 综合征，诊断为 IgMPC-TIN。开始给予 PSL（30mg/天，0.4mg/kg/天）治疗，疾病标志物立即下降。然而，当 PSL 减至 15mg/天（0.2mg/kg/天）时，患者血清 IgM 水平升高；因此，我们维持 PSL 剂量为 15mg/天（0.2mg/kg/天）。
我们报告了三例与糖皮质激素治疗减少或停用相关的复发 IgMPC-TIN 病例。在这些病例中，血清 IgM 升高先于其他标志物，如尿β-微球蛋白、蛋白尿和糖尿。我们建议在减少糖皮质激素时监测血清 IgM 水平；如果怀疑或预计复发，应考虑维持糖皮质激素剂量。
