Pichler Sekulic Simona, Negrea Lavinia, Pradhan Nishigandha, Kalahasti Priya, Kansal Sheru, Sekulic Miroslav
Clin Nephrol. 2020 Sep;94(3):155-160. doi: 10.5414/CN110163.
Monoclonal immunoglobulin paraproteins can deposit in the kidney in variable forms and eliciting differing patterns of injury. Crystalglobulin-induced nephropathy is a rare form of monoclonal immunoglobulin deposition in the kidney, characterized by glomerular capillary endoluminal crystalline material evident by light and electron microscopy that exhibits immunoglobulin restriction via immunofluorescence studies. We present a case of a patient with acute kidney injury, and a subsequent kidney biopsy notably revealed concurrent monoclonal immunoglobulin deposition disease (MIDD) and crystalglobulin-induced nephropathy secondary to an IgM/κ monoclonal protein that resulted in a membranoproliferative pattern of glomerular injury. The two process were distinctly evident by ultrastructural crystalline and non-crystalline (as seen with cases of more conventional MIDD) deposits in the glomeruli. The paraprotein constituency is novel (IgM/κ) for crystalglobulin-induced nephropathy (prior cases exhibited IgG/κ restriction) as was the finding of the two monoclonal immunoglobulin deposition processes contributing to development of an active glomerulitis characterized by a membranoproliferative pattern of glomerular injury (crystalglobulin-induced nephropathy has not been associated with an active glomerulitis before).
单克隆免疫球蛋白副蛋白可呈多种形式沉积于肾脏，引发不同的损伤模式。结晶球蛋白诱导的肾病是单克隆免疫球蛋白在肾脏沉积的一种罕见形式，其特征为在光镜和电镜下可见肾小球毛细血管腔内有结晶物质，通过免疫荧光研究显示出免疫球蛋白受限。我们报告一例急性肾损伤患者，随后的肾活检显著显示并发单克隆免疫球蛋白沉积病（MIDD）以及继发于IgM/κ单克隆蛋白的结晶球蛋白诱导的肾病，导致肾小球损伤呈现膜增生性模式。通过肾小球超微结构中的结晶和非结晶（如更典型的MIDD病例所见）沉积物，这两个过程明显不同。该副蛋白组成对于结晶球蛋白诱导的肾病来说是新的（IgM/κ）（之前的病例显示为IgG/κ受限），而且发现两种单克隆免疫球蛋白沉积过程导致了以肾小球损伤膜增生性模式为特征的活动性肾小球肾炎的发展（此前结晶球蛋白诱导的肾病未曾与活动性肾小球肾炎相关联）。
