[Anaplastic lymphoma kinase-translocation renal cell carcinoma: clinical and pathological analysis].

Objective: To investigate the clinicopathological features, molecular characteristics, differential diagnosis and prognosis of anaplastic lymphoma kinase (ALK)-translocation renal cell carcinoma. Methods: Two cases of ALK-translocation renal cell carcinoma diagnosed from January 2011 to December 2020 were retrospectively analyzed to characterize their morphological features, immunohistochemical expression and prognosis. Multiple molecular studies including fluorescence in situ hybridization (FISH), reverse transcriptase-polymerase chain reaction (RT-PCR), and next-generation sequencing were performed to characterize the genetic alterations. Results: Two patients included one male and one female, with 59 and 57 years old, respectively. Morphologically, case 1 resembled collecting duct carcinoma or renal medullary carcinoma, which demonstrated tubular, microcapsule and reticular structures, with a remarkable myxoid background and lymphocytes infiltration; case 2 resembled Xp11.2 translocation renal cell carcinoma or type 2 papillary renal cell carcinoma, which demonstrated tubular papillary and focal solid structures, with flocculent cytoplasm and many foamy histiocytes, but without myxoid background and lymphocytes infiltration. Immunohistochemistry showed strongly positive expression of ALK. CK7, E-cadherin, vimentin, PAX8 and CD10 showed various degrees of expression, and other antibodies were nonreactive. A variety of molecular assays showed definite ALK gene translocation, with rare VCL-ALK gene fusion (VCL exon and 16-ALK exon 20) in case 1, and EML4-ALK gene fusion (EML4 exon and 2-ALK exon 20) in case 2. Conclusions: ALK-translocation renal cell carcinoma is rare with various morphological features, and is easy to miss and misdiagnose. The characteristic ALK expression and molecular detection of ALK translocation are helpful for diagnosing this type of renal cell carcinoma.目的： 探讨间变性淋巴瘤激酶（ALK）易位性肾细胞癌的临床病理学、分子遗传学、鉴别诊断及预后。 方法： 回顾性分析解放军东部战区总医院2011年1月至2020年12月收集的2例ALK易位性肾细胞癌的组织形态学特征、免疫组织化学表达以及相关预后信息，采用荧光原位杂交（FISH）技术、逆转录聚合酶链式反应（RT-PCR）、高通量靶向测序等多项分子检测分析其分子病理特征。 结果： 男女各1例，年龄分别为59岁和57岁。形态学上，例1类似于肾集合管癌或髓质癌，呈小管状、微囊网状结构，具有显著的黏液背景及淋巴细胞浸润；例2则类似于Xp11.2易位性肾细胞癌或Ⅱ型乳头状肾细胞癌，呈管状乳头状、局部实性结构，肿瘤细胞胞质呈絮状，间质内见多量泡沫样组织细胞，未见黏液背景及淋巴细胞浸润。免疫表型方面，2例均强阳性表达ALK蛋白，此外细胞角蛋白7、E-cadherin、波形蛋白、PAX8和CD10呈现不同程度的表达，其余标志物均为阴性。多种分子检测技术均明确显示ALK基因易位，例1为罕见的VCL-ALK融合基因，融合位点为VCL基因的第16号外显子和ALK基因的第20号外显子；例2为EML4-ALK融合基因，融合位点为EML4基因的第2号外显子和ALK基因的第20号外显子。 结论： ALK易位性肾细胞癌较为罕见，形态多样，容易漏诊和误诊。特征性的ALK蛋白表达和分子检测ALK基因重排有助于该类型肾癌的确诊。.