Iijima M, Nakazato Y
Department of Pathology, Gunma University School of Medicine, Maebashi, Japan.
Pathol Int. 1997 Jan;47(1):25-30. doi: 10.1111/j.1440-1827.1997.tb04431.x.
Cerebellar medulloblastomas are the most common embryonal neoplasms occurring in the pediatric age group. Thirty-five specimens from 28 cases of medulloblastoma and variant neoplasms were examined to elucidate the histopathologic significance of the reticulin-free pale islands. In 10 specimens, there were light-looking areas corresponding to pale islands: three specimens from desmoplastic and seven from classic medulloblastoma. The difference in cell population, 1.73-fold more cells in dark areas than in light areas (P < 0.001), seemed to be a major factor in the formation of the biphasic architecture. Immunohistochemically, occasional tumor cells in both areas were found to express neuronal phenotypes. In addition, positive immunoreactivity for glial markers was exceptional. There was significant difference in the staining indices (SI) for cell proliferation markers. The light areas consistently showed low SI values (mean MIB-1 SI, 5.75; mean PCNA SI, 11.8) compared with the dark areas (mean MIB-1 SI, 22.7; mean PCNA SI, 44.9). It is suggested that light areas (pale islands) consist of more differentiated cells of neuronal lineage with relatively low proliferation potential. These tumor cells might proliferate in a group, and then expand, thereby compressing the surrounding tissue to form pale islands.
小脑髓母细胞瘤是小儿年龄组中最常见的胚胎性肿瘤。对28例髓母细胞瘤及变异型肿瘤的35个标本进行检查，以阐明无网状纤维淡染岛的组织病理学意义。在10个标本中，存在与淡染岛相对应的浅色区域：3个标本来自促结缔组织增生型，7个来自经典型髓母细胞瘤。细胞数量的差异，即深色区域的细胞比浅色区域多1.73倍（P < 0.001），似乎是形成双相结构的主要因素。免疫组织化学检查发现，两个区域偶尔有肿瘤细胞表达神经元表型。此外，胶质细胞标志物的阳性免疫反应罕见。细胞增殖标志物的染色指数（SI）存在显著差异。与深色区域（平均MIB-1 SI为22.7；平均PCNA SI为44.9）相比，浅色区域的SI值始终较低（平均MIB-1 SI为5.75；平均PCNA SI为11.8）。提示浅色区域（淡染岛）由具有相对低增殖潜能的神经元谱系中分化程度更高的细胞组成。这些肿瘤细胞可能成群增殖，然后扩展，从而压迫周围组织形成淡染岛。
