Department of Experimental and Clinical Neuropathology, Medical Research Centre, Polish Academy of Sciences, 5 Pawinskiego Str., 02-106 Warsaw, Poland.
Neuropathology. 2011 Aug;31(4):427-32. doi: 10.1111/j.1440-1789.2010.01168.x. Epub 2010 Nov 24.
Rosette-forming glioneuronal tumor (RGNT) of the fourth ventricle is a recently described novel type of primary brain tumor that was included into the current WHO classification of CNS tumors. It is a very rare, slowly growing, mixed neoplasm at cerebellar localization with distinctive morphological pattern. We present an unusual case of a 20-year-old patient with RNGT of the fourth ventricle with advanced microvascular proliferation. MRI revealed the solid-cystic tumor mass largely involving the cerebellar vermis and left hemisphere with compression of the fourth ventricle. Microscopically, the tumor showed classical architectural pattern with two distinctive components. The main component consisted of neurocytic rosettes formed by round, isomorphic nuclei arranged around eosinophilic, fibrillar cores with strong synaptophysin expression. The perivascular rosettes with cell arrangement along blood vessels were observed only sporadically. The second neoplastic component consisted of spindle or stellate astroglial cells with piloid process and Rosenthal fibers, strongly resembling pilocytic astrocytoma. Focally, the astroglial cells showed increased cellularity but without marked nuclear atypia. The glial part of the tumor revealed advanced proliferation of microvessels. The vessels of glomeruloid type exhibited multilayered endothelial proliferation and marked mitotic activity. MIB1 labelling index was generally low; however, in areas exhibiting microvascular proliferation its expression was significantly increased up to 20%. This report demonstrates the unique case of RGNT with conspicuous microvascular proliferation of glomeruloid type and extensive endothelial proliferation. As there is still limited clinical experience with RGNT, further studies are necessary to evaluate the biology of this type of tumor.
四脑室胶神经元肿瘤（RGNT）是一种新近描述的新型原发性脑肿瘤，被纳入了现行 CNS 肿瘤 WHO 分类。它是一种非常罕见的、生长缓慢的、以小脑定位为特征的混合性肿瘤，具有独特的形态学模式。我们报告了一例不常见的 20 岁患者，患有四脑室 RGNT 伴高级微血管增殖。MRI 显示了广泛累及小脑蚓部和左半球的实性-囊性肿瘤肿块，伴有第四脑室受压。显微镜下，肿瘤显示出经典的建筑模式，具有两个独特的成分。主要成分由神经细胞形成的神经细胞玫瑰花组成，这些玫瑰花由排列在嗜酸性纤维状核心周围的圆形、同形核组成，具有强烈的突触素表达。仅偶尔观察到沿血管排列的血管玫瑰花。第二个肿瘤成分由梭形或星状星形胶质细胞组成，具有纤毛过程和 Rosenthal 纤维，强烈类似于毛细胞星形细胞瘤。局灶性地，星形胶质细胞显示出细胞增多，但没有明显的核异型性。肿瘤的神经胶质部分显示出微血管的高级增殖。肾小球样的血管表现为多层内皮增殖和明显的有丝分裂活性。MIB1 标记指数通常较低；然而，在显示微血管增殖的区域，其表达显著增加至 20%。本报告展示了一例具有明显肾小球样微血管增殖和广泛内皮增殖的 RGNT 独特病例。由于对 RGNT 的临床经验仍然有限，需要进一步研究来评估这种肿瘤的生物学特性。
