Recurrent medulloblastoma can be difficult to diagnose with conventional diagnostic methods because other lesions mimic tumor relapse, particularly at later stages. We report 2 cases of medulloblastoma, both of which seemed to develop late recurrences. Case 1 was a 6-year-old girl who had a medulloblastoma with focal desmoplasia. She was in complete remission for 9 years after treatment but developed an intradural lesion in her thoracic spine, which was pathologically confirmed as tumor recurrence by biopsy. Case 2 was a 10-year-old girl who had a nonmetastatic medulloblastoma. She developed a left cerebellar mass 5 years after the initial diagnosis; the pathological diagnosis was tumor relapse. We performed t-distributed stochastic neighbor embedding of the methylation data from these cases and reference data. In contrast to the consistency of methylation profiling and copy number abnormalities between primary and recurrent tumors of Case 1, the analysis of the recurrent tumor in Case 2 was distinct from medulloblastomas and clustered with “IDH-wild type glioblastomas,” suggesting that the recurrent tumor was a radiation-induced glioblastoma. This report highlights the clinical utility of molecular genetic/epigenetic analysis combined with a standard diagnostic approach to confirm the diagnosis of brain tumor recurrence.

中文翻译：

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应用全基因组 DNA 甲基化分析区分放射诱导的胶质母细胞瘤和晚期复发的髓母细胞瘤

复发性髓母细胞瘤很难用常规诊断方法诊断，因为其他病变模仿肿瘤复发，特别是在后期。我们报告了 2 例髓母细胞瘤，这两例似乎都发生了晚期复发。病例 1 是一名 6 岁女孩，患有髓母细胞瘤伴局灶性结缔组织增生。治疗后9年完全缓解，但胸椎出现硬膜内病变，活检病理证实为肿瘤复发。病例 2 是一名患有非转移性髓母细胞瘤的 10 岁女孩。初次诊断 5 年后，她出现左侧小脑肿块；病理诊断为肿瘤复发。我们对来自这些病例和参考数据的甲基化数据进行了 t 分布随机邻域嵌入。与病例 1 的原发性和复发性肿瘤之间甲基化谱和拷贝数异常的一致性相反，病例 2 中复发性肿瘤的分析与髓母细胞瘤不同，并与“IDH-野生型胶质母细胞瘤”聚集在一起，表明复发性肿瘤是一种辐射诱发的胶质母细胞瘤。本报告强调了分子遗传学/表观遗传学分析与标准诊断方法相结合的临床实用性，以确认脑肿瘤复发的诊断。