后纵隔苗勒管囊肿22例临床病理分析

Clinicopathological analysis of 22 cases of posterior mediastinal Müllerian cyst

目的 探讨后纵隔苗勒管囊肿的临床病理学特征、诊断及鉴别诊断。方法 收集890例纵隔囊肿患者的临床及影像学资料,经组织学和免疫组化法筛选出22例苗勒管囊肿,分析其临床影像学及病理学特征,并复习相关文献。结果 苗勒管囊肿占纵隔囊肿的2.5%(22/890),占后纵隔囊肿的42.3%(22/52),患者均为女性,平均年龄46岁(年龄范围:33~55岁);均发生于后纵隔T1~7椎旁水平,CT诊断为良性神经源性肿瘤12例(54.5%)。临床信息完整者16例,体重正常者9例(56.3%),超重或肥胖者7例(43.8%),93.8%(15/16)的患者具有卵巢囊肿、激素替代治疗或流产等妇科疾病史。病理检查示后纵隔苗勒管囊肿均为单房囊性肿物,囊肿内衬纤毛柱状细胞及分泌细胞,上皮细胞局部形成黏膜皱褶和乳头结构,类似输卵管上皮;囊壁由薄层不连续的平滑肌组织及纤维结缔组织构成。免疫表型:上皮细胞ER、PR、CK7、WT-1及PAX-8均阳性,TTF-1、Calretinin、CK5/6和p40均阴性;囊壁内薄层平滑肌组织SMA阳性,CD10阴性。结论 纵隔苗勒管囊肿常发生于后纵隔椎体旁,是中年女性纵隔囊肿的少见病理类型,由类似输卵管上皮及薄层平滑肌组织组成的良性囊肿,上皮细胞ER、PR、WT-1和PAX-8均阳性有助于诊断;后纵隔囊肿应将苗勒管囊肿纳入鉴别诊断。

Purpose To investigate the clinicopathological features, diagnosis and differential diagnosis of mediastinal Müllerian cyst. Methods The clinical and imaging data of 890 patients of mediastinal cysts, were retrospectively analyzed, and 22 cases of posterior Müllerian cysts were diagnosed by histology and immunohistochemistry. Their radiological features and clinicopathological characteristics were summerized, and the related literatures were also reviewed. Results Posterior Müllerian cysts accounted for 2.5%(22/890) of mediastinal cysts and 42.3%(22/52) of posterior mediastinal cysts, respectively. All patients were female with the mean age of 46 years(age range: 33-55 years). All lesions were located in the posterior mediastinum, at the level of T1-7vertebrae, and 12 cases(54.5%) were diagnosed as benign neurogenic tumors according to the CT findings. Clinical information was accessible for 16 cases, 9 patients(56.3%) were normal weight, 7 cases(43.8%) were overweight and obese. 93.8%(15/16) patients had a history of gynecological diseases such as ovarian cysts, hormone replacement therapy or abortion history. All lesions were unilocular cystic masses. Microscopically, the posterior mediastinal Müllerian cyst showed that the thin-walled cyst was lined with ciliated columnar cells and secretory cells, and the epithelial cells formed mucosal folds and papillary structures, which were similar to the fallopian tube epithelium cells. The cyst wall underlying the epithelium cells was composed of thin layer of discontinuous smooth muscle tissue and fibrous connective tissue. Immunohistochemical results showed that the epithelium cells were positive for ER, PR, CK7, WT-1 and PAX-8, and negative for TTF-1, Calretinin, CK5/6 and p40. The smooth muscle tissue in the cyst wall was positive for SMA and negative for CD10. Conclusion Posterior mediastinal Müllerian cysts are rare and benign cysts, which are generally located in the paravertebral of posterior mediastinal and mostly occur in middle-aged women, composed of epithelial cells resembling structures of the fallopian tube and thin layers of smooth muscle underlying. Posterior mediastinal Müllerian cyst is easily misdiagnosed and the expression of ER, PR, WT-1 and PAX-8 in epithelial cells is helpful for the diagnosis. Müllerian cyst should be considered in the differential diagnosis of posterior mediastinal cyst.