Kidney failure is common in patients with a monoclonal gammopathy, most frequently due to hypercalcemia or myeloma cast nephropathy. Immunoglobulin crystallization is an uncommon phenomenon that also results in kidney injury. We report the case of a 74-year-old man with recurrent renal colic and acute kidney injury. He presented with κ light chain Bence-Jones proteinuria, hypogammaglobulinemia, anemia, and high plasma κ light chain level, leading to the diagnosis of κ light chain multiple myeloma. One calculus was collected and its analysis revealed a unique protein structure consisting of κ immunoglobulin free light chain. Genetic sequencing of the κ light chain identified a subgroup of variable domain previously identified as prone to crystallization. Eight cycles of cyclophosphamide-bortezomib-dexamethasone chemotherapy resulted in a partial hematologic response and kidney recovery without recurrence of renal colic. This rare case of urinary light chain nephrolithiasis highlights the importance of genetic and molecular analysis of the immunoglobulin variable domain to better understand the wide spectrum of monoclonal gammopathies.

肾功能衰竭在患有单克隆性丙种球蛋白病的患者中很常见，最常见的原因是高钙血症或骨髓瘤引起的肾病。免疫球蛋白结晶是一种罕见现象，还会导致肾脏损伤。我们报告了一名74岁的男子反复肾绞痛和急性肾损伤的情况。他表现为κ轻链Bence-Jones蛋白尿，低血球蛋白血症，贫血和血浆κ轻链水平高，导致κ轻链多发性骨髓瘤的诊断。收集了一个牙结石，其分析揭示了一种独特的蛋白质结构，该结构由无κ免疫球蛋白的轻链组成。κ轻链的遗传测序确定了一个可变结构域的亚组，该亚组以前被确定为易于结晶。八个周期的环磷酰胺-硼替佐米-地塞米松化疗导致部分血液学反应和肾脏恢复，而没有肾绞痛复发。这种罕见的尿轻链肾结石病病例凸显了对免疫球蛋白可变域进行遗传和分子分析的重要性，以更好地了解单克隆血友病的广谱范围。