[Clinicopathological features and diagnosis of pericytic tumors of the kidney].

Objective: To investigate the clinicopathologic features,diagnosis and prognosis of pericytic tumor of the kidney. Methods: Three cases of pericytic tumor of the kidney (two cases were diagnosed as glomangiomyomas and one case as pericytic tumor,unclassified) were collected from the affiliated Hospital of Qingdao University between January 2014 to May 2021; the clinical and morphologic features, immunohistochemical and molecular characteristics were analyzed and the relevant literature was reviewed. Results: The three patients included one male and two females, with ages ranging from 21 to 70 years. In two patients the tumors were detected incidentally at physical examination and one patient presented with low back discomfort. Imaging showed a rounded nodular soft tissue density shadow in renal parenchyma, and enhancement scan showed uneven delayed enhancement. Grossly, two tumors were located in the renal hilum and one in the renal parenchyma; all were nodular. The tumors were measured in size from 1.6 cm to 5.1 cm (mean 4.1 cm) and showed gray or gray-red cut surface. Histologic examination showed the tumor cells were arranged in solid sheets or small nodules, closely related to vascular wall. Tumor cells were mostly epithelial-like with abundant cytoplasm, light eosinophilia, obscure boundary and round nuclei with visible nucleoli. Vague bundles and fascicular arrangements of smooth muscle component were noted in some areas, with transition of both components. There was no necrosis. By immunohistochemistry, the tumor cells strongly and diffusely expressed vimentin, SMA and collagen Ⅳ, two cases expressed CD34, all three cases expressed PDGFRB to varying extent, and the Ki-67 index was 2%-3%. PCR tests showed absent K-RAS, BRAF V600E gene mutation in all three cases. PDGFRB mutations in exons 3 and 18, respectively were found in two of the three cases by high-throughput sequencing, and no NOTCH 1/2/3 gene fusions were found in any of them. Follow-up information (range: 6-92 months) showed no evidence of local recurrence or distant metastasis in all three patients. Conclusions: Pericytic tumor of the kidney is a rare mesenchymal tumor originating in the kidney with differentiation to smooth muscle, most commonly glomus tumor. The mild pleomorphism, close relationship with vascular wall and spindled smooth muscle components suggest the diagnosis of the tumor. Expression of both epithelial and muscle-associated markers aids the diagnosis. PDGFRB gene mutations may have an important role in the development of this tumor. Most patients have a good prognosis, and a few cases have malignant biological behavior.目的： 探讨肾脏血管周细胞肿瘤的临床病理学特点及诊断、预后。 方法： 收集青岛大学附属医院2014年1月至2021年5月病理确诊的3例肾脏血管周细胞肿瘤（2例为球血管肌瘤，1例难以分类，诊断为血管周细胞肿瘤），分析其临床、形态学、免疫表型及分子学特点，并进行文献复习。 结果： 3例中男性1例，女性2例。年龄21~70岁。2例因体检发现，1例因腰部不适就诊。影像学显示肾实质内类圆形结节状软组织密度影，增强扫描往往呈不均性延迟强化。大体检查：2例位于肾门处，1例位于肾实质内，均呈结节状，直径1.6~5.1 cm（平均4.1 cm），切面灰白或灰红色，质韧。光镜下观察：瘤细胞实性片状或小结节状排列，与血管壁关系密切，瘤细胞多呈上皮样，胞质丰富、浅嗜酸，边界不清，核圆形，可见核仁，部分区域可见多少不一的长梭形、束状排列的平滑肌成分，两种成分有过渡移行，所有肿瘤均无坏死。免疫组织化学染色：瘤细胞波形蛋白、平滑肌肌动蛋白及Ⅳ型胶原弥漫强阳性，2例表达CD34，3例均不同程度表达PDGFRB，Ki-67阳性指数2%~3%。聚合酶链反应检测显示，3例均未见KRAS、BRAF V600E基因突变；二代基因测序检测，3例中有2例发现PDGFRB基因突变，分别为第3和第18外显子突变，均未发现NOTCH 1/2/3基因融合。3例随访6~92个月，所有患者均健在，无复发或转移。 结论： 肾脏血管周细胞肿瘤是一种原发于肾脏向平滑肌分化的罕见间叶性肿瘤，以血管球瘤最常见，瘤细胞形态温和、与血管壁关系密切并见梭形的平滑肌成分对该肿瘤的诊断具有重要提示作用，免疫组织化学上皮性和肌源性标记的联合应用有助于诊断。PDGFRB基因突变在该肿瘤的发生中可能具有重要作用。多数预后良好，少部分病例具有恶性生物学行为。.