Department of Pathology, Hospital Álvaro Cunqueiro, Clara Campoamor Av., 341, 36312, Vigo, Spain.
Uropathology Research Group, Galicia Sur Health Research Institute (IIS Galicia Sur), SERGAS-UVIGO, Vigo, Spain.
Virchows Arch. 2021 Jul;479(1):57-67. doi: 10.1007/s00428-021-03018-4. Epub 2021 Jan 14.
Clear cytoplasm is a major characteristic feature of most malignant renal neoplasms. Benign clear cells in the renal parenchyma, usually histiocytes, can occasionally be found, but they are infrequently of an epithelial nature. We report histological, immunohistochemical, ultrastructural, and cytogenomic features of clear epithelial cell clusters incidentally found in four kidney specimens. Multiple microscopic clear cell clusters were present in the cortex, often in subcapsular location. They were composed of large epithelial cells with strikingly clear cytoplasm, without nuclear atypia, arranged in solid nests, and some tubules with narrow lumina. Immunohistochemically, they were positive for AE1AE3, PAX 8, EMA, kidney-specific cadherin, cytokeratin 7, E cadherin, and CD117, with focal immunoreactivity for CD10. Carbonic anhydrase IX, vimentin, and markers related to apoptosis and proliferation were negative. Ultrastructurally, the cytoplasms were enlarged and poor in organelles, showing ballooning degeneration. Array comparative genomic hybridization showed no chromosomal gains or losses. Clear cell clusters constitute a rare finding in the kidney and must be differentiated from benign lesions (ectopic adrenal tissue, osmotic tubulopathy, histiocytic clusters, renal adenomas) and renal cell carcinomas. Clear cell clusters appear to be generated from "endocrine-type" atrophic tubules whose cells are enlarged due to intracellular oedema. Immunohistochemistry shows a distal nephron phenotype with a limited expression of a proximal marker, CD10. Coexisting chronic renal disease or ischemic conditions seem to be related to the development of clear cell clusters. Pathological, ultrastructural, and cytogenomic features do not support a preneoplastic nature of this lesion, at least in the cases studied here.
细胞质透明是大多数恶性肾肿瘤的主要特征。肾实质中的良性透明细胞，通常为组织细胞，偶尔也能发现，但通常为上皮性质。我们报告了偶然发现在 4 个肾标本中的透明上皮细胞簇的组织学、免疫组织化学、超微结构和细胞遗传学特征。多个微小的透明细胞簇存在于皮质中，通常位于包膜下位置。它们由具有明显透明细胞质的大上皮细胞组成，无核异型性，呈实性巢状排列，部分呈窄腔小管状。免疫组织化学染色显示 AE1AE3、PAX8、EMA、肾脏特异性钙黏蛋白、细胞角蛋白 7、E 钙黏蛋白和 CD117 阳性，CD10 呈局灶性免疫反应性。碳酸酐酶 IX、波形蛋白以及与凋亡和增殖相关的标志物均为阴性。超微结构显示，细胞质增大，细胞器减少，呈气球样变性。阵列比较基因组杂交显示无染色体增益或丢失。透明细胞簇在肾脏中是一种罕见的发现，必须与良性病变（异位肾上腺组织、渗透管状病变、组织细胞簇、肾腺瘤）和肾细胞癌相鉴别。透明细胞簇似乎是由“内分泌型”萎缩小管产生的，其细胞由于细胞内水肿而增大。免疫组织化学显示远端肾单位表型，近端标志物 CD10 表达有限。并存的慢性肾脏病或缺血情况似乎与透明细胞簇的发生有关。病理、超微结构和细胞遗传学特征不支持该病变具有肿瘤前性质，至少在本研究中是这样。
