Department of Pathology, Immunology and Laboratory Medicine, Center for the Study of Lithiasis, College of Medicine, University of Florida, Gainesville, Florida 32601, USA.
J Urol. 2012 Mar;187(3):1094-100. doi: 10.1016/j.juro.2011.10.125. Epub 2012 Jan 21.
Idiopathic calcium oxalate kidney stones develop by calcium oxalate crystal deposition on Randall plaque. The mechanisms involved in Randall plaque formation are still unclear. We hypothesized that Randall plaque formation is similar to that of vascular calcification, involving components of extracellular matrix, including membrane bound vesicles and collagen fibers. To verify our hypothesis we critically examined renal papillary tissue from patients with stones.
We performed 4 mm cold cup biopsy of renal papillae on 15 patients with idiopathic stones undergoing percutaneous nephrolithotomy. Tissue was immediately fixed and processed for analysis by various light and electron microscopic techniques.
Spherulitic calcium phosphate crystals, the hallmark of Randall plaque, were seen in all samples examined, including in interstitium and laminated basement membrane of tubular epithelium. Large crystalline deposits were composed of dark elongated strands mixed with spherulites. Strands showed banded patterns similar to collagen. Crystal deposits were surrounded by collagen fibers and membrane bound vesicles. Energy dispersive x-ray microanalysis and electron diffraction identified the crystals as hydroxyapatite. Few kidneys were examined and urinary data were not available on all patients.
Results showed that crystals in Randall plaque are associated with collagen and membrane bound vesicles. Collagen fibers appeared calcified and vesicles contained crystals. Crystal deposition in renal papillae may have started with membrane vesicle induced nucleation and grown by the further addition of crystals at the periphery in a collagen framework.
特发性草酸钙肾结石是通过草酸钙晶体在 Randall 斑上沉积而形成的。涉及 Randall 斑形成的机制仍不清楚。我们假设 Randall 斑的形成类似于血管钙化，涉及细胞外基质的成分，包括膜结合小泡和胶原纤维。为了验证我们的假设，我们对有结石的患者的肾乳头组织进行了仔细检查。
我们对 15 例接受经皮肾镜碎石术的特发性结石患者进行了 4mm 冷杯肾乳头活检。组织立即固定并通过各种光镜和电镜技术进行分析。
所有检查的样本中均可见球晶状磷酸钙晶体，这是 Randall 斑的标志，包括间质和管状上皮的分层基底膜。大的结晶沉积物由深色的拉长链与球晶混合而成。链显示出与胶原相似的条带图案。晶体沉积物被胶原纤维和膜结合小泡包围。能谱 X 射线微分析和电子衍射鉴定晶体为羟基磷灰石。仅对少数肾脏进行了检查，并非所有患者都有尿液数据。
结果表明，Randall 斑中的晶体与胶原和膜结合小泡有关。胶原纤维似乎钙化，小泡中含有晶体。肾乳头中的晶体沉积可能始于膜小泡诱导的成核，并在胶原框架上通过进一步在外周添加晶体而生长。
