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Abstract：
OBJECTIVE: Malignant intracranial germ cell tumors (GCTs) are rare diseases in Western countries. They arise in midline structures and diagnosis is often delayed. We evaluated imaging characteristics and early tumor signs of suprasellar and bifocal GCT on MRI.
METHODS: Patients with the diagnosis of a germinoma or non-germinomatous GCT (NGGCT) who received non-contrast sagittal T1WI on MRI pre-therapy were included. Loss of the posterior pituitary bright spot (PPBS), the expansion and size of the tumor, and the expansion and infiltration of surrounding structures were evaluated. Group comparison for histologies and localizations was performed.
RESULTS: A total of 102 GCT patients (median age at diagnosis 12.3 years, range 4.4-33.8; 57 males; 67 in suprasellar localization) were enrolled in the study. In the suprasellar cohort, NGGCTs (n = 20) were noticeably larger than germinomas (n = 47; p < .001). Each tumor showed involvement of the posterior lobe or pituitary stalk. A PPBS loss (total n = 98) was observed for each localization and entity in more than 90% and was related to diabetes insipidus. Osseous infiltration was observed exclusively in suprasellar GCT (significantly more frequent in NGGCT; p = .004). Time between the first MRI and therapy start was significantly longer in the suprasellar cohort (p = .005), with an even greater delay in germinoma compared to NGGCT (p = .002). The longest interval to treatment had circumscribed suprasellar germinomas (median 312 days).
CONCLUSIONS: A loss of the PPBS is a hint of tumor origin revealing small tumors in the neurohypophysis. Using this sign in children with diabetes insipidus avoids a delay in diagnosis.
METHODS: Patients with the diagnosis of a germinoma or non-germinomatous GCT (NGGCT) who received non-contrast sagittal T1WI on MRI pre-therapy were included. Loss of the posterior pituitary bright spot (PPBS), the expansion and size of the tumor, and the expansion and infiltration of surrounding structures were evaluated. Group comparison for histologies and localizations was performed.
RESULTS: A total of 102 GCT patients (median age at diagnosis 12.3 years, range 4.4-33.8; 57 males; 67 in suprasellar localization) were enrolled in the study. In the suprasellar cohort, NGGCTs (n = 20) were noticeably larger than germinomas (n = 47; p < .001). Each tumor showed involvement of the posterior lobe or pituitary stalk. A PPBS loss (total n = 98) was observed for each localization and entity in more than 90% and was related to diabetes insipidus. Osseous infiltration was observed exclusively in suprasellar GCT (significantly more frequent in NGGCT; p = .004). Time between the first MRI and therapy start was significantly longer in the suprasellar cohort (p = .005), with an even greater delay in germinoma compared to NGGCT (p = .002). The longest interval to treatment had circumscribed suprasellar germinomas (median 312 days).
CONCLUSIONS: A loss of the PPBS is a hint of tumor origin revealing small tumors in the neurohypophysis. Using this sign in children with diabetes insipidus avoids a delay in diagnosis.
摘要：
目的：恶性颅内生殖细胞肿瘤（GCT）是西方国家罕见的疾病。它们出现在中线结构中，诊断通常会延迟。我们在MRI上评估了鞍上和双焦点GCT的影像学特征和早期肿瘤征象。
方法：包括诊断为生殖细胞瘤或非生殖细胞性GCT（NGGCT）的患者，在MRI治疗前接受非对比矢状T1WI。垂体后叶亮点（PPBS）的丧失，肿瘤的扩大和大小，并对周围结构的膨胀和渗透进行了评价。进行组织学和定位的组比较。
结果：共102例GCT患者（诊断时的中位年龄12.3岁，范围4.4-33.8；57位男性；67位在鞍上定位）被纳入研究。在鞍上队列中，NGGCT（n=20）明显大于生殖细胞瘤（n=47；p<.001）。每个肿瘤均显示后叶或垂体柄受累。在超过90%的每个定位和实体中观察到PPBS损失(总计n=98),并且与尿崩症有关。仅在鞍上GCT中观察到骨浸润（在NGGCT中明显更频繁；p=.004）。在鞍上队列中，第一次MRI和治疗开始之间的时间明显更长（p=0.005），与NGGCT相比，生殖细胞瘤的延迟甚至更大（p=0.002）。最长的治疗间隔是有限的鞍上生殖细胞瘤（中位数312天）。
结论：PPBS的丢失是肿瘤起源的提示，显示神经垂体中的小肿瘤。在尿崩症患儿中使用此体征可避免诊断延迟。
方法：包括诊断为生殖细胞瘤或非生殖细胞性GCT（NGGCT）的患者，在MRI治疗前接受非对比矢状T1WI。垂体后叶亮点（PPBS）的丧失，肿瘤的扩大和大小，并对周围结构的膨胀和渗透进行了评价。进行组织学和定位的组比较。
结果：共102例GCT患者（诊断时的中位年龄12.3岁，范围4.4-33.8；57位男性；67位在鞍上定位）被纳入研究。在鞍上队列中，NGGCT（n=20）明显大于生殖细胞瘤（n=47；p<.001）。每个肿瘤均显示后叶或垂体柄受累。在超过90%的每个定位和实体中观察到PPBS损失(总计n=98),并且与尿崩症有关。仅在鞍上GCT中观察到骨浸润（在NGGCT中明显更频繁；p=.004）。在鞍上队列中，第一次MRI和治疗开始之间的时间明显更长（p=0.005），与NGGCT相比，生殖细胞瘤的延迟甚至更大（p=0.002）。最长的治疗间隔是有限的鞍上生殖细胞瘤（中位数312天）。
结论：PPBS的丢失是肿瘤起源的提示，显示神经垂体中的小肿瘤。在尿崩症患儿中使用此体征可避免诊断延迟。
