化生型胸腺瘤17例临床病理观察

Clinicopathological characteristics of 17 cases of metaplastic thymoma

目的探讨化生型胸腺瘤(metaplastic thymoma,MT)的临床病理学特征。方法回顾性分析17例MT的临床病理学及免疫表型特征,并进行随访。采用免疫组化EnVision两步法对17例MT进行检测,并复习相关文献。结果17例MT中女性8例,男性9例,年龄28~74岁,平均51岁。临床表现均无重症肌无力。肿瘤最大径1.5~9.5 cm,平均5.1 cm。镜下见肿瘤显示双相分化:上皮细胞和梭形细胞交错分布,部分区相互移行。上皮细胞轻度异型,可见核内假包涵体;梭形细胞呈束状排列,细胞温和;两种成分核分裂象均罕见。免疫表型:上皮细胞区域CK(AE1/AE3)、CK19、p63弥漫阳性;梭形细胞区域vimentin、EMA弥漫阳性;Ki-67增殖指数均﹤5%。随访5~79个月,均无复发或转移。结论MT是一种生物学行为惰性的胸腺肿瘤,其独特的组织学特征及免疫表型有助于诊断及鉴别诊断。

Purpose To investigate the clinicopathological features,immunophenotype,diagnosis and prognosis of metaplastic thymoma(MT).Methods The clinicopathological characteristics and immunophenotype of 17 cases of MT were retrospectively analyzed and followed up.Results There were 8 females and 9 males aged from 28 to 74 years(average age 51 years).None had myasthenia gravis.The maximum diameter of the tumor was 1.5-9.5 cm(mean 5.1 cm).Microscopically,the tumor showed biphasic differentiation:epithelioid and spindle cells interlacing,with some areas migrating to each other.Epithelial cells were slightly atypic,and pseudo-inclusion bodies were easily seen in nuclei.Spindle cells arranged in bundles,and the cells were bland.Mitotic figures of both components were rare.Immunophenotypically,epithelial cells were diffusely positive for CK(AE1/AE3),CK19 and p63,spindle cells expressed vimentin and EMA.Ki-67 proliferation index was less than 5%.During the follow-up period of 5 to 79 months,there was no recurrence or metastasis.Conclusion MT is a rare and low-grade thymic tumor.Its unique histological features and immunophenotype are helpful for diagnosis and differential diagnosis.