Aslanova Afag, Ishida Masanori, Takahashi Reisuke, Suzuki Yutaro, Arizono Elly, Wakabayashi Yukari, Ohno Yoshio, Nagao Toshitaka, Saito Kazuhiro
Radiology, Tokyo Medical University Hospital, Tokyo, JPN.
Pathology, Tokyo Medical University Hospital, Tokyo, JPN.
Cureus. 2024 Oct 16;16(10):e71667. doi: 10.7759/cureus.71667. eCollection 2024 Oct.
Postpubertal-type teratomas are rare malignant tumors derived from germ cell neoplasia in situ (GCNIS). This case report presents a rare instance of a retroperitoneal postpubertal-type teratoma as a late recurrence of a testicular germ cell tumor (GCT) that was initially diagnosed as a seminoma. A 48-year-old male who had undergone left inguinal orchidectomy for a testicular mass was diagnosed with a seminoma (stage I) six years prior and presented with an asymptomatic 6-cm retroperitoneal tumor near the left renal hilum. Initial blood tests at presentation for the retroperitoneal tumor were normal, except for a mild elevation of lactate dehydrogenase. Computed tomography (CT), magnetic resonance imaging, and fluorine-18-fluorodeoxyglucose positron emission tomography (18F-FDG PET)/CT imaging revealed a well-defined tumor with calcification and high glucose metabolic activity. A CT-guided biopsy for the retroperitoneal tumor suggested a high-grade malignant tumor of neuroendocrine origin. The patient underwent neoadjuvant chemotherapy, which resulted in tumor shrinkage and decreased metabolic activity. Subsequent surgical resection and histopathological examination revealed a postpubertal-type teratoma with a concomitant neuroendocrine tumor. A reexamination of the previous testicular tumor specimen revealed a small amount of embryonal carcinoma within the seminoma, indicating that the initial diagnosis should have been a mixed germ cell tumor rather than a pure seminoma. This explains the unusual recurrence pattern observed and highlights the importance of a thorough histological examination for testicular GCTs, as microscopic non-seminomatous components can significantly affect prognosis and recurrence patterns. When encountering suspected recurrences of GCNIS-derived GCTs, clinicians should consider the possibility of an initially undetected mixed GCT, particularly in cases with atypical presentation or recurrence patterns.
青春期后型畸胎瘤是源自原位生殖细胞肿瘤（GCNIS）的罕见恶性肿瘤。本病例报告展示了一例罕见的腹膜后青春期后型畸胎瘤，它是最初被诊断为精原细胞瘤的睾丸生殖细胞肿瘤（GCT）的晚期复发。一名48岁男性因睾丸肿物接受了左腹股沟睾丸切除术，六年前被诊断为精原细胞瘤（I期），此次出现左肾门附近一个无症状的6厘米腹膜后肿瘤。腹膜后肿瘤初诊时的血液检查除乳酸脱氢酶轻度升高外均正常。计算机断层扫描（CT）、磁共振成像以及氟-18-氟脱氧葡萄糖正电子发射断层扫描（18F-FDG PET）/CT成像显示一个边界清晰、有钙化且葡萄糖代谢活性高的肿瘤。对腹膜后肿瘤进行的CT引导下活检提示为神经内分泌起源的高级别恶性肿瘤。患者接受了新辅助化疗，肿瘤缩小且代谢活性降低。随后的手术切除及组织病理学检查显示为青春期后型畸胎瘤伴发神经内分泌肿瘤。对之前睾丸肿瘤标本的重新检查发现精原细胞瘤内有少量胚胎癌成分，这表明最初的诊断应为混合性生殖细胞肿瘤而非单纯精原细胞瘤。这解释了所观察到的不寻常复发模式，并凸显了对睾丸GCT进行全面组织学检查的重要性，因为显微镜下的非精原细胞瘤成分可显著影响预后和复发模式。当遇到疑似源自GCNIS的GCT复发时，临床医生应考虑最初未被发现的混合性GCT的可能性，尤其是在表现不典型或复发模式异常的病例中。
