Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indiana University Health Pathology Laboratory, Indianapolis, IN, United States.
Pathology. 2018 Jan;50(1):88-99. doi: 10.1016/j.pathol.2017.07.013. Epub 2017 Nov 10.
Accurate diagnosis of primary and metastatic tumours is essential in testicular cancer. While many cases are straightforward, some pose difficulties, especially when variant morphologies occur. Seminoma with 'atypical' features, including increased nuclear pleomorphism and crowding and greater cytoplasmic density with loss of membrane definition, mimics embryonal carcinoma, although ancillary features (fibrous septa, lymphocytes) and immunohistochemistry are of great help. Other deceptive seminoma features include prominent to exclusive intertubular growth, microcystic/tubular patterns, and signet-ring tumour cells. Conversely, embryonal carcinomas may have 'seminoma-like' foci, as may Sertoli cell tumours with diffuse growth and pale cytoplasm. Solid pattern yolk sac tumour mimics seminoma and, conversely, microcytic seminoma resembles yolk sac tumour. Other architectural patterns, ancillary yolk sac tumour features (intercellular basement membrane deposits, hyaline cytoplasmic globules) and immunohistochemistry aid in distinction from seminoma. Embryonal carcinomas may show, in addition to 'seminoma-like' foci, pseudoendodermal sinus-like structures, sieve-like patterns, endometrioid-like morphology and prominent zones of stratified columnar tumour cells. These may cause confusion with yolk sac tumour and teratoma, although careful attention to cytological features usually suffices for accurate diagnosis. Recent work has defined 'new' primary trophoblastic tumours, i.e., cystic trophoblastic tumour and epithelioid trophoblastic tumour. The newly termed 'spermatocytic tumour' occasionally consists mostly of a monotonous proliferation of intermediate-sized tumour cells with prominent nucleoli, thereby simulating either seminoma or embryonal carcinoma. Prostatic adenocarcinoma remains the most common tumour to metastasise to the testis and can cause confusion with rete carcinomas and primary germ cell tumours. Post-chemotherapy resections pose their own challenges. Effete tumour cells in areas of necrosis and prominent fibroxanthomatous reactions should not be interpreted as persistent, viable germ cell tumour. 'Fibrosis' often has atypical widely scattered spindle tumour cells in a densely collagenous background but does not merit additional treatment apart from excision. The marked cytological atypia that may occur in metastatic teratoma may be disconcerting but, again, the proper treatment is complete surgical excision rather than more chemotherapy. Glandular and sarcomatoid yolk sac tumours, which are almost exclusively seen after chemotherapy, resemble adenocarcinomas and sarcomas, respectively. Unlike de novo malignancies, they are mostly seen in sites expected for metastases.
准确诊断原发性和转移性肿瘤对于睾丸癌至关重要。虽然许多病例很直接，但有些则具有挑战性，尤其是当出现变体形态时。具有“非典型”特征的精原细胞瘤，包括核多形性增加、拥挤和细胞质密度增加、细胞膜定义丧失，类似于胚胎癌，尽管辅助特征（纤维间隔、淋巴细胞）和免疫组织化学检查非常有帮助。其他具有欺骗性的精原细胞瘤特征包括突出的或排他性的小管间生长、微囊/管状模式和印戒细胞肿瘤。相反，胚胎癌可能具有“精原细胞瘤样”病灶，而弥漫性生长和淡染细胞质的支持细胞瘤也可能如此。实性卵黄囊瘤模式类似于精原细胞瘤，而微细胞精原细胞瘤类似于卵黄囊瘤。其他结构模式、辅助卵黄囊瘤特征（细胞间基底膜沉积物、透明细胞质小球）和免疫组织化学有助于与精原细胞瘤区分。除了“精原细胞瘤样”病灶外，胚胎癌还可能显示出假内胚窦样结构、筛状模式、子宫内膜样形态和分层柱状肿瘤细胞的明显区域。这些可能会导致与卵黄囊瘤和畸胎瘤混淆，尽管仔细注意细胞学特征通常足以进行准确诊断。最近的研究定义了“新”原发性滋养层肿瘤，即囊性滋养层肿瘤和上皮样滋养层肿瘤。新命名的“精原细胞瘤”偶尔由中等大小的肿瘤细胞单调增殖组成，具有明显的核仁，因此模拟精原细胞瘤或胚胎癌。前列腺腺癌仍然是最常见转移到睾丸的肿瘤，并可能与 rete 癌和原发性生殖细胞肿瘤混淆。化疗后切除带来了自身的挑战。坏死区域的无效肿瘤细胞和明显的纤维黄色瘤反应不应被解释为持续存在的、有活力的生殖细胞肿瘤。“纤维化”通常在致密胶原背景中有非典型的广泛分散的梭形肿瘤细胞，但除了切除外，不需要额外的治疗。转移性畸胎瘤中可能出现的明显细胞异型性可能令人不安，但同样，正确的治疗方法是完全手术切除，而不是更多的化疗。腺癌和肉瘤样卵黄囊瘤，几乎仅见于化疗后，分别类似于腺癌和肉瘤。与新发病变不同，它们主要见于预期转移的部位。
