Abstract: Objective  To study the clinical, neuroimaging and histopathological features of intracranial germinoma.  Methods  One case of intracranial germinoma with ventricular system dissemination was reported, and related literatures were reviewed.  Results  A 34-year-old male complained of progressive dizziness for 30 d and manifested unsteady gait for 45 d. Radiological examinations revealed low signal intensity on T₁WI and hyperintense on T₂WI in the corpus callosum, left cerebellum, around the fourth ventricle, aqueduct mesencephalon, the ventral pons and pineal region, with even or uneven enhancement after contrast. The clinical initial diagnosis was "intracranial multiple focal lesions and high possibility of multiple sclerosis". After well response to glucocorticoid impact and dehydration, the patient stopped taking drugs but presented relapse and exacerbation. Later, he underwent biopsy on pineal region and was diagnosed as intracranial germinoma. Microscopically, the big germ cells and lymphocytes coexisted. Tumor cells were epithelioid cells with transparent cytoplasm, prominent nuclei and mitotic activity. Lymphocytes were distributed along interstitial substance of vessel and fiber, and individual syncytiotrophoblasts were sprasely distributed. Immunohistochemical staining showed tumor cells were positive for CD117 and OCT3/4, and the syncytiotrophoblasts were positive for β-human chorionic gonadotropin ( β-hCG). The clinical symptoms were completely alleviated after radiotherapy and chemotherapy.  Conclusions  Because of the sensitivity for radiotherapy and chemotherapy, intracranial germinoma can be diagnosed and treated early to improve its prognosis. However, it is very easy to disseminate along with ventricular system and form multiple lesions, leading to atypical clinical and imaging manifestations, which is a big challenge for clinical diagnosis.

Key words: Germinoma, Pineal gland, Cerebral ventricles, Neoplasm metastasis, Immunohistochemistry, Pathology

摘要： 目的 探讨颅内生殖细胞瘤的临床、影像学和组织病理学特征。方法与结果 男性患者，34 岁。头晕30 d，渐进性加重伴行走不稳45 d。MRI显示胼胝体、左侧小脑、第四脑室周围、中脑导水管和脑桥腹侧、松果体区长T1、长T2 信号；病灶呈均匀或不均匀强化。临床拟诊：颅内多发性病变，可疑多发性硬化。经糖皮质激素冲击治疗和降低颅内压后病情缓解，但停药后病情复发且进一步加重，经松果体区病变组织活检明确诊断为颅内生殖细胞瘤。组织形态学表现为：肿瘤细胞与成熟淋巴细胞双相成分，肿瘤细胞为上皮样细胞，胞质透亮、核仁明显、核分裂象易见，淋巴细胞沿血管纤维间质分布，并散在个别合体滋养层细胞；免疫组织化学染色，肿瘤细胞表达CD117、OCT3/4，合体滋养层细胞表达β-人绒毛膜促性腺激素。经放射治疗和药物化疗，临床症状完全缓解。结论 颅内生殖细胞瘤对放射治疗和药物化疗的敏感性使早期诊断与治疗成为改善患者预后的首要条件，然而其易沿脑室系统播散，形成多发病变，导致临床症状和影像学表现不典型，给临床诊断造成巨大挑战，在临床工作中应提高警惕。

关键词: 生殖细胞瘤, 松果腺, 脑室, 肿瘤转移, 免疫组织化学, 病理学