伴淋巴样间质的微结节型胸腺瘤7例临床病理分析

Micronodular thymoma with lymphoid stroma:a clinicopathological study of seven cases

目的探讨伴淋巴样间质的微结节型胸腺瘤(MNT)的临床病理特征、诊断及鉴别诊断。方法回顾性分析7例MNT患者的临床资料、病理学特征、免疫表型、治疗及预后,并复习相关文献。结果7例MNT患者中,男性4例,女性3例;年龄44~71岁,平均年龄58岁。病灶均位于前纵隔,其中3例位于前上纵隔,1例位于左前中纵隔。2例为重症肌无力,4例无症状者胸部CT显示纵隔占位,1例因尿频尿急行前列腺穿刺示高级别上皮内瘤变(HGPIN),同时全身检查示纵隔占位。镜下2例为单纯MNT,1例合并胸腺囊肿,4例合并其他类型胸腺瘤(2例为AB型胸腺瘤,1例为B2型胸腺瘤,1例为A型胸腺瘤);7例均包膜完整,1例局灶包膜侵犯,其余6例包膜无肿瘤侵犯。镜下MNT示多灶分散或融合的小上皮样结节被大量淋巴细胞间质分隔,微结节由短梭形或卵圆形细胞组成,核染色质均匀,核仁不明显,未见核分裂和坏死。上皮细胞PCK、CK19、CK5/6表达阳性,且CD20、CD5、CD117表达阴性。淋巴间质细胞主要为CD20^(+)/CD79a^(+)B细胞,混有部分CD3^(+)/CD5^(+)/TdT-T细胞。7例MNT均行胸腔镜下纵隔肿物切除术,随访4~55个月,患者均存活且无复发和转移。结论MNT较罕见,无特殊性临床表现,易与其他类型胸腺瘤合并,经病理形态学并结合免疫表型可明确诊断。治疗以手术切除为主,患者预后较好。

Objective To investigate the clinicopathological features,diagnosis and differential diagnosis of micronodular thymoma with lymphoid stroma(MNT).Methods The clinical data,pathological features,immunophenotypes,treatments and prognosis of 7 cases of MNT patients were retrospectively analyzed,and relevant literatures were reviewed.Results There were 4 males and 3 females among the 7 patients,aged 44-71 years,with an average age of 58 years old.The lesions were all located in the anterior mediastinum,with 3 cases located in the anterior superior mediastinum and 1 case located in the left anterior middle mediastinum.Two cases were myasthenia gravis,4 asymptomatic cases had mediastinal mass on CT scanning,1 case underwent prostate puncture biopsy showing focal high-grade prostatic intraepithelial neoplasia(HGPIN)due to frequent and urgent urination,and the mediastinal mass was detected by systemic examination.Microscopically,2 cases were pure MNT,1 case was accompanied with thymic cyst,4 cases were accompanied with other types of thymoma(2 cases of AB type thymoma,1 case of B2 type thymoma,1 case of type A thymoma).The capsule was intact in 7 cases,with focal capsule invasion in 1 case,without tumor invasion of the capsules in 6 cases.Microscopically,MNT showed small epithelioid nodules with multifocal dispersion or fusion separated by a large number of lymphocyte stroma.Micronodules were composed of short spindle-shaped or oval cells,with uniform nuclear chromatins,without obvious nucleolus,and nuclear mitosis and necrosis were not observed.Epithelial cells were positive for PCK,CK19 and CK5/6,and negative for CD20,CD5 and CD117.Lymphatic stromal cells were mainly CD20^(+)/CD79a^(+)B cells mixed with some CD3^(+)/CD5^(+)/TdT-T cells.Thoracoscopic mediastinal mass resection was performed in 7 patients.The follow-up time was 4-55 months.All of them were alive and did not have recurrence and metastasis.Conclusion MNT was rare,had no specific clinical manifestations,was easy to merge with other types of thymoma,and can be clearly diagnosed by pathological morphology combined with immunophenotyping.MNT is mainly treated by surgical resection,and the prognosis of patients is good.