Abstract：
Extragonadal germ cell tumors (EGCTs) are rare, representing <5% of all germ cell tumors (GCTs). Whilst EGCTs share morphological and immunohistochemical features with their gonadal counterparts, they tend to be more aggressive and are frequently associated with secondary somatic malignancies. The aim of our study was to evaluate the clinical, morphological and immunohistochemical features, and to analyze tumors for chromosomal abnormalities of 12p, in addition to any novel genetic alterations, in a series of EGCTs. Seventy-seven EGCTs were included. Anterior mediastinum was the most common anatomic site, followed by central nervous system, retroperitoneum, sacroccygeal area, and neck. Whole genome SNP array identified isochromosome 12p in 26% of tumors. Additional cytogenetic abnormalities included the presence of gain of chr 21 in 37% of tumors. Somatic-type malignancies were identified in 8% of patients. Disease progression (metastasis and/or recurrence) was documented in 8 patients, most of whom died from their relapse. Three patients who died of disease had somatic-type malignancies. Mediastinal seminomas had a significantly better overall survival when compared to mediastinal non-seminomatous GCTs. Our study demonstrates that EGCTs share similar histologic features, but diverse clinical outcomes compared to their gonadal counterparts. Outcomes vary according to anatomic location and histologic subtypes. Our data corroborate that somatic-type malignancies are frequently encountered in mediastinal EGCTs and that their presence portends a poorer prognosis.
摘要：
性腺外生殖细胞肿瘤（EGCT）是罕见的，代表<5%的所有生殖细胞肿瘤（GCT）。虽然EGCT与它们的性腺对应物具有相同的形态学和免疫组织化学特征，它们往往更具侵袭性，并且经常与继发性躯体恶性肿瘤相关。我们研究的目的是评估临床，形态学和免疫组织化学特征，并分析肿瘤的12p染色体异常，除了任何新的基因改变，在一系列EGCT中。包括77个EGCT。前纵隔是最常见的解剖部位，其次是中枢神经系统，腹膜后,骶尾部区域，和脖子。全基因组SNP阵列在26%的肿瘤中鉴定了同位染色体12p。另外的细胞遗传学异常包括在37%的肿瘤中存在chr21的增加。在8％的患者中发现了体细胞型恶性肿瘤。8例患者出现疾病进展（转移和/或复发），他们中的大多数死于复发。死于疾病的三名患者患有躯体型恶性肿瘤。与纵隔非精原细胞瘤GCT相比，纵隔精原细胞瘤的总生存期明显更好。我们的研究表明，EGCT具有相似的组织学特征，但不同的临床结果相比，他们的性腺同行。结果因解剖位置和组织学亚型而异。我们的数据证实，纵隔EGCT中经常遇到体细胞型恶性肿瘤，并且它们的存在预示着预后较差。
