睾丸非特殊类型支持细胞瘤临床病理学和分子特征分析

Clinicopathologic and molecular characterizations of Sertoli cell tumor, not otherwise specified of the testis

目的探讨睾丸非特殊类型支持细胞瘤（SCT，NOS）的组织形态谱、免疫表型特点和分子遗传学特征。方法收集2008年至2017年间北京大学第三医院（4例）和浙江省人民医院（3例）共7例睾丸SCT，NOS，HE染色观察其组织病理学特征，免疫组织化学染色采用EnVision两步法观察钙网蛋白（calretinin）、抑制素、β－catenin、cyclin D1、CD10、广谱细胞角蛋白（CK）、神经内分泌标志物、WT1、Melan A、波形蛋白、SALL4、GATA3、PAX8以及S－100蛋白等标志物的表达，应用聚合酶链反应（PCR）和直接测序法对肿瘤组织进行CTNNB1基因第3号外显子点突变分析。结果7例肿瘤发病年龄28-65岁（平均约43岁），临床上均表现为缓慢增大的无痛性睾丸肿物。瘤体最大径1.5-3.0 cm（平均2.1 cm），切面灰白略呈分叶状。镜下肿瘤界限清楚，无包膜。瘤细胞呈实性片状、梁索状、缎带状以及实性或中空小管状排列，分布于多少不等的纤维性间质之中；其中2例可见明显的硬化性间质，符合硬化性支持细胞瘤的组织学亚型；1例可见明显的间质黏液变性。瘤细胞胞质较丰富，弱嗜酸性或浅染，2例可见多少不等的富于脂质的泡沫状胞质，2例可见散在的多核瘤细胞聚集。瘤细胞核形态温和，未见不典型性，2例可见核分裂象（约1个/50 HPF），未见坏死。免疫组织化学染色：7/7弥漫表达波形蛋白和CD10，5/7弥漫异常核质表达β－catenin，其中5/5均弥漫核表达cyclin D1，另2例均为弥漫膜表达β－catenin，而cyclin D1均阴性。5/7局灶或弥漫表达广谱CK，5/6局灶表达calretinin，3/7局灶表达抑制素，2/6局灶表达突触素，4/5局灶或弥漫表达CD56，4/5弥漫核表达WT1，3/7弥漫表达S－100蛋白。嗜铬粒素A、Melan A、PAX8、GATA3、SALL4等均阴性。PCR和测序分析发现4/7（约57%）可见CTNNB1基因第3号外显子点突变，其中4例CTNNB1突变的肿瘤免疫表型上均表现为β－catenin的弥漫异常核质表达和cyclin D1的核表达。结论睾丸SCT，NOS在组织学和免疫表型特点上可表现出明显的异质性，较易于误诊。分子遗传学分析半数以上的肿瘤可见CTNNB1基因第3号外显子的点突变，免疫组织化学染色异常核质表达β－catenin和核表达cyclin D1，可助于其诊断和鉴别诊断。

Objective To investigate the histomorpholgic spectrum, immunophenotypic, and molecular genetic features of Sertoli cell tumor, not otherwise specified （ SCT, NOS） of the testis. Methods Seven cases of SCT, NOS of the testis were analyzed （4 from Peking University Third Hospital and 3 from Zhejiang Provincial People＇s Hospital） between 2008 and 2017. The histopathologic features were examined based on HE staining, and EnVision method was used for immunohistochemistry staining of calretinin, inhibin, 13-catenin, cyclinD1, CD10, CKpan, neuroendocrine markers, WT1, Melan A, vimentin, SALL4,GATA3, PAX8, and S-100 protein. Mutational analysis of exon 3 of the CTNNB1 gene by polymerase chain reaction （PCR）-amplified sequences and direct sequencing was performed. Results Patients ages ranged from 22 to 65 years （ mean 43 years ）. The clinical manifestation in all was a slowly enlarging, painless testicular mass. The maximum diameter of the tumor ranged from 1.5 cm to 3.0 cm （ mean 2. 1 cm ） . Sectioning usually disclosed a tan-gray to white mass with vague lobular cut-surface. Microscopically, the tumors were well circumscribed and non-encapsulated; the tumor cells were rearranged in multiple growth patterns from diffuse solid sheets to trabeeulae and cords, ribbon and solid or hollow tubules setting in variable amount of acellular fibrous stroma. Two cases showed acellular collagenous stroma constituted 〉50% of the tumor confirming to the diagnosis of sclerosing SCT. One case demonstrated a prominent myxoid stromal change. The tumor cells typically had moderate amounts of pale to lightly eosinophilic cytoplasm, 2 tumors had variable ceils with abundant lipid-rich cytoplasm, and 1 other tumor showed scattered aggregates of multinucleated tumor cells. The tumor cells were bland-appearing without any evidence of atypia, mitoses were noted in 2 tumors （both were 1/50 HPF）, but necrosis was absent. Immunohistochemical staining results as follows ： vimentin （ diffuse, 7/7） , CD 10 （ diffuse membrane, 7/7 ） ; diffuse [3-catenin nuclear and cytoplasm staining in 5 of 7 cases, and all the 5 cases showed diffuse cyclin D1 nuclear staining, [3-catenin membrane staining in 2 of 7 cases, CKpan （ 5/7, focal or diffuse）, calretinin （focal, 5/6）, inhibin （focal, 3/7）, synaptophysin （focal, 2/6）, CD56 （focal or diffuse, 4/5）, WT1 （diffuse nuclear, 4/5）, and S-100 protein （diffuse, 3/7）, and chromogranin A, Melan A, PAX8, GATA3 and SALL4 all were negative. Molecular genetic studies of PCR and direct sequencing showed CTNNB1 mutations in 4 of 7 （4/7） cases, 4 of the four mutation-carrying cases showed diffuse β-catenin nuclear and cytoplasm immunoreactivity and diffuse cyehn D1 nuclear immunoreactivity in the tumor cells. Conclusions SCT, NOS of the testis typically shows significant heterogeneities in both morphology and immunohistochemistry, thus causing differential diagnostic confusions. Molecular analyses showed mutations of exon 3 of CTNNB1 in more than half of these tumors, and nuclear accumulation of β-catenin and over expression of cyclin D1 can be useful for the differential diagnosis of SCT, NOS.