Nephropathology Associates, Little Rock, AR 72211, USA.
Mod Pathol. 2011 Nov;24(11):1462-9. doi: 10.1038/modpathol.2011.104. Epub 2011 Jun 24.
The renal diseases most frequently associated with myeloma include amyloidosis, monoclonal immunoglobulin deposition disease, and cast nephropathy. Less frequently reported is light chain proximal tubulopathy, a disease characterized by κ-restricted crystal deposits in the proximal tubule cytoplasm. Light chain proximal tubulopathy without crystal deposition is only loosely related to the typical light chain proximal tubulopathy, and little is known about this entity. A search was performed of the 10 081 native kidney biopsy samples processed by our laboratory over the past 2 years for cases that had light chain restriction limited to the proximal tubule cytoplasm. A total of 10 cases of light chain proximal tubulopathy without crystal deposition were found representing 3.1% of light chain-related diseases. Nine of these 10 showed λ-light chain restriction. Only three cases of light chain proximal tubulopathy with crystals were found accounting for 0.9% of light chain-related diseases. Two of these three were κ subtype. Plasma cell dyscrasia was unsuspected in seven of the 10 patients with light chain proximal tubulopathy without crystals at the time of renal biopsy. After the biopsy was reported, follow-up was available on 9/10 patients with 9/9 showing a plasma cell dyscrasia including 8/9 with multiple myeloma. We found that light chain proximal tubulopathy without crystal formation, despite being rarely described in the literature, is over three times more common than light chain proximal tubulopathy with crystal formation in our series. And given that it is often associated with previously unrecognized myeloma, it is a critically important diagnosis.
与骨髓瘤最常相关的肾脏疾病包括淀粉样变性、单克隆免疫球蛋白沉积病和铸型肾病。较少报道的是轻链近端肾小管病，这是一种特征为近端肾小管细胞质中κ限制晶体沉积的疾病。无晶体沉积的轻链近端肾小管病与典型的轻链近端肾小管病相关性较弱，对该疾病知之甚少。对过去 2 年中我们实验室处理的 10081 例原发性肾脏活检样本进行了搜索，以寻找仅局限于近端肾小管细胞质的轻链限制病例。共发现 10 例无晶体沉积的轻链近端肾小管病，占轻链相关性疾病的 3.1%。这 10 例中有 9 例显示 λ 轻链限制。仅发现 3 例有晶体的轻链近端肾小管病，占轻链相关性疾病的 0.9%。其中 2 例为 κ 亚型。在 10 例无晶体沉积的轻链近端肾小管病患者中，有 7 例在肾活检时浆细胞异常未被怀疑。在报告活检后，对 9/10 例患者进行了随访，9/9 例患者均存在浆细胞异常，包括 8/9 例多发性骨髓瘤。我们发现，尽管在文献中很少描述，但无晶体形成的轻链近端肾小管病在我们的系列中比有晶体形成的轻链近端肾小管病常见三倍以上。并且由于它通常与以前未被识别的骨髓瘤有关，因此这是一个非常重要的诊断。
