Department of Pathology, Seoul National University Hospital, Seoul, 03080, Republic of Korea.
Department of Internal Medicine, Seoul National University Hospital, Seoul, 03080, Republic of Korea.
BMC Nephrol. 2020 Apr 23;21(1):146. doi: 10.1186/s12882-020-01813-w.
Light chain proximal tubulopathy (LCPT) is a rare paraproteinemic renal disease that has been mostly reported in Western patients. LCPT is characterized by the accumulation of immunoglobulin (Ig)-light chain (LC) in the proximal tubule. Immunohistochemical staining for Ig-LC has not been investigated in the context of LCPT. We reported the clinicopathological characteristics and Ig-LC immunoexpression of patients with LCPT for the first time in Korea.
We reviewed the clinicopathological findings of 5 Korean patients diagnosed with LCPT between 2016 and 2018. In addition, immunohistochemical staining for κ-LC and λ-LC was conducted on paraffin-embedded tissues.
The median age was 63 years, and the male-to-female ratio was 3:2. The primary renal manifestations were either azotemia or tubular proteinuria. All patients were diagnosed with multiple myeloma with monoclonal κ-LC (#1-2) or λ-LC (#3-5) in the serum and urine. Kidney biopsies revealed diverse and subtle alterations of the proximal tubule, including crystallization, vacuolization, and/or swelling. Electron microscopy revealed crystals in patients #1-2 and non-crystalline particles within numerous/large/dysmorphic lysosomes in patients #3-5. Ig-LC restriction was demonstrated in the proximal tubule as κ-type in patients #1-2 and as λ-type in patients #3-5 by immunohistochemistry and immunofluorescence. Immunohistochemical staining showed diffuse positivity to κ- and λ-LC, although immunofluorescent staining for κ-LC was focal and weak. LCPT has diverse clinicopathological characteristics and subtle morphological alterations, which necessitate ancillary tests for diagnosis.
We introduced immunohistochemical staining for Ig-LC as a useful tool for the diagnosis of LCPT, especially in the case of κ-type crystals.
轻链近端肾小管病（LCPT）是一种罕见的副蛋白血症性肾脏疾病，主要见于西方患者。LCPT 的特征是免疫球蛋白（Ig）-轻链（LC）在近端肾小管中蓄积。在 LCPT 中尚未研究 Ig-LC 的免疫组织化学染色。我们首次在韩国报告了 LCPT 患者的临床病理特征和 Ig-LC 免疫表达。
我们回顾了 2016 年至 2018 年间诊断为 LCPT 的 5 例韩国患者的临床病理发现。此外，对石蜡包埋组织进行 κ-LC 和 λ-LC 的免疫组织化学染色。
中位年龄为 63 岁，男女比例为 3:2。主要的肾脏表现为氮质血症或管状蛋白尿。所有患者均诊断为多发性骨髓瘤，血清和尿液中存在单克隆 κ-LC（#1-2）或 λ-LC（#3-5）。肾脏活检显示近端肾小管的多种微妙改变，包括结晶、空泡化和/或肿胀。电子显微镜显示患者 #1-2 中有晶体，患者 #3-5 中有大量/大/异常溶酶体中的非晶形颗粒。免疫组织化学和免疫荧光显示，近端肾小管中 Ig-LC 呈 κ 型限制，患者 #1-2 为 κ 型，患者 #3-5 为 λ 型。免疫组织化学染色显示 κ-LC 和 λ-LC 弥漫阳性，尽管 κ-LC 的免疫荧光染色为局灶性和弱阳性。LCPT 具有多种临床病理特征和微妙的形态改变，需要辅助检查进行诊断。
我们引入了 Ig-LC 的免疫组织化学染色作为诊断 LCPT 的有用工具，特别是在 κ 型晶体的情况下。
