Wilson R W, Moran C A
Department of Pulmonary and Mediastinal Pathology, Armed Forces Institute of Pathology, Washington, DC, USA.
Ann Diagn Pathol. 1998 Oct;2(5):293-300. doi: 10.1016/s1092-9134(98)80021-x.
Primary mediastinal ependymomas are unusual tumors, with only two case reports previously reported in the literature. In this study, we review our experience with three cases of primary mediastinal ependymomas, including the clinical, histopathologic, immunohistochemical, and ultrastructural features. The three patients in this study were white women with a mean age of 50 years (age range, 36 to 71 years). Presenting symptoms were nonspecific; radiographically, all lesions were circumscribed posterior mediastinal masses without evidence of bone involvement. There was no evidence of central nervous system, sacral, or pelvic ependymoma. All tumors were completely resected, ranged in size from 5 to 7 cm (mean, 6 cm), and exhibited glistening pseudocapsules. Two tumors had a solid, tan-gray cut surface and one lesion was cystic with a mural tumor nodule. All neoplasms showed histologic features of conventional cellular ependymomas with perivascular pseudorosettes and occasional true ependymal rosettes. Germ cell components were not present in any case and immunohistochemical analysis showed glial fibrillary acidic protein, S-100, and patchy cytokeratin immunoreactivity in all three cases as well as absence of reactivity for HMB 45, chromogranin, and synaptophysin. Ultrastructural features included multipart "zipper-like" junctions, intracytoplasmic lumina containing microvilli, occasional cytoplasmic basal bodies, and apical cilia. A microscopic metastasis was present in a regional lymph node in one case at the time of resection; however, there is no evidence of recurrence or distant metastasis in any of the cases during the postoperative period (mean length of follow-up, 64 months). Ependymomas rarely occur in the mediastinum and have a predilection for the posterior mediastinum. The paravertebral location, microscopic identification of adjacent sympathetic ganglia, and lack of teratomatous or other germ cell components suggest that mediastinal ependymomas are likely derived from paravertebral ependymal rests. Primary mediastinal ependymomas are characterized by a prolonged and indolent clinical course. Metastasis to regional lymph nodes may occur, but distant metastases are unusual in our experience. Complete surgical excision seems to offer the best chance for long-term survival.
原发性纵隔室管膜瘤是一种罕见的肿瘤，此前文献中仅报道过两例。在本研究中，我们回顾了三例原发性纵隔室管膜瘤的诊治经验，包括临床、组织病理学、免疫组化及超微结构特征。本研究中的三名患者均为白人女性，平均年龄50岁（年龄范围36至71岁）。临床表现无特异性；影像学检查显示，所有病变均为边界清晰的后纵隔肿块，无骨质受累迹象。无中枢神经系统、骶部或盆腔室管膜瘤证据。所有肿瘤均完整切除，大小为5至7厘米（平均6厘米），表面有光泽的假包膜。两个肿瘤切面呈实性、棕灰色，一个病变为囊性，伴有壁内肿瘤结节。所有肿瘤均表现为典型的细胞型室管膜瘤组织学特征，可见血管周围假菊形团，偶尔可见真性室管膜菊形团。所有病例均未发现生殖细胞成分，免疫组化分析显示，三例肿瘤均有胶质纤维酸性蛋白、S-100及局灶性细胞角蛋白免疫反应，而HMB 45、嗜铬粒蛋白及突触素均无反应。超微结构特征包括多部分 “拉链样” 连接、含微绒毛的胞质内管腔、偶尔的胞质基体及顶端纤毛。一例患者在切除时区域淋巴结出现显微镜下转移；然而，术后随访期间（平均随访时间64个月），所有病例均无复发或远处转移证据。室管膜瘤很少发生于纵隔，且好发于后纵隔。肿瘤位于椎旁、显微镜下可见相邻交感神经节，且无畸胎瘤或其他生殖细胞成分，提示纵隔室管膜瘤可能起源于椎旁室管膜残余组织。原发性纵隔室管膜瘤的临床病程长且进展缓慢。区域淋巴结转移可能发生，但据我们的经验，远处转移并不常见。完整手术切除似乎是实现长期生存的最佳机会。
