Lindberg Eva, Persson Annette, Øra Ingrid, Mertens Fredrik, Englund Elisabet, Gisselsson David
Department of Pathology, University Hospital, Lund, Sweden.
Neuropathology. 2007 Dec;27(6):556-60. doi: 10.1111/j.1440-1789.2007.00810.x.
Medullomyoblastoma (MMB) is a rare cerebellar childhood tumor containing both myoblastic and primitive neuroectodermal components. Similar to the scenario in classical medulloblastoma, which contains the primitive neuroectodermal component only, gain of sequences from the long arm of chromosome 17 (17q) and gain of the MYC gene in 8q have been implicated in the pathogenesis of MMB. Because karyotypic analysis has not previously been performed for MMB, the mechanisms behind genomic imbalances in this tumor have remained unknown. Several other central aspects of this tumor, such as histocytogenetic origin, clinical characteristics, tumor behavior and prognosis, also remain unknown. We here report neuropathological and cytogenetic features of an MMB in a 3-year-old boy. Chromosome banding analysis and multicolor karyotyping revealed a hyperdiploid karyotype including an unbalanced 1; 17 translocation and isochromosome 17q formation, both leading to gain of 17q. There were also two extra copies of chromosome 8, leading to gain of the MYC oncogene, trisomies 5 and 13, and monosomy 9. Clonal chromosome changes were present in both the myoblastic and neuroectodermal components. Our findings support the notion that MMB and classical medulloblastoma arise through similar genetic mechanisms and that the two main tissue components in MMB are clonally related.
髓母细胞瘤（MMB）是一种罕见的儿童小脑肿瘤，包含成肌细胞和原始神经外胚层成分。与仅包含原始神经外胚层成分的经典髓母细胞瘤情况类似，17号染色体长臂（17q）序列的增加以及8q中MYC基因的增加与MMB的发病机制有关。由于此前尚未对MMB进行核型分析，该肿瘤基因组失衡背后的机制仍然未知。该肿瘤的其他几个核心方面，如组织细胞遗传学起源、临床特征、肿瘤行为和预后，也仍然未知。我们在此报告一名3岁男孩的MMB的神经病理学和细胞遗传学特征。染色体带型分析和多色核型分析显示为超二倍体核型，包括不平衡的1；17易位和17q等臂染色体形成，两者均导致17q增加。还有两条额外的8号染色体，导致MYC癌基因增加、5号和13号染色体三体以及9号染色体单体。成肌细胞和神经外胚层成分均存在克隆性染色体变化。我们的研究结果支持以下观点，即MMB和经典髓母细胞瘤通过相似的遗传机制产生，并且MMB中的两个主要组织成分是克隆相关的。
