Diffuse leptomeningeal glioneuronal tumor (DLGNT) was introduced, for the first time, as a provisional entity in the 2016 WHO classification of central nervous system tumors. DLGNT mainly occur in children and characterized by a widespread leptomeningeal growth occasionally associated with intraspinal tumor nodules, an oligodendroglial-like cytology, glioneuronal differentiation and MAP-Kinase activation associated with either solitary 1p deletion or 1p/19q codeletion in the absence of IDH mutation. We report here two unexpected DLGNTs adult cases, characterized by a unique supratentorial circumscribed intraparenchymal tumor without leptomeningeal involvement in spite of long follow-up. In both cases, the diagnosis of DLGNT was made after DNA-methylation profiling which demonstrated that one case belonged to the DLGNT class whereas the other remained not classifiable but showed on CNV the characteristic genetic findings recorded in DLGNT. Both cases harbored 1p/19q codeletion associated with KIAA1549:BRAF fusion in one case and with BRAF V600E and PIK3CA E545A mutations, in the other. Our study enlarges the clinical and molecular spectrum of DLGNTs, and points out that the terminology of DLGNTs is not fully appropriate since some cases could have neither diffuse growth nor leptomeningeal dissemination. This suggests that DLGNTs encompass a wide spectrum of tumors that has yet to be fully clarified.

中文翻译：

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弥漫性软脑膜神经胶质神经胶质瘤：双重误称？两例报告。

弥漫性软脑膜神经胶质神经元肿瘤（DLGNT）首次作为2016年WHO WHO中枢神经系统肿瘤分类中的临时实体被引入。DLGNT主要发生在儿童中，其特征是有时与脊柱内肿瘤结节相关的广泛的脑膜神经生长，少突胶质细胞样细胞学，神经胶质神经元分化和MAP-激酶活化与IDP突变的情况下单独的1p缺失或1p / 19q编码相关。我们在这里报告了两个意外的DLGNTs成年病例，其特征是尽管没有长期随访，但幕上外接有局限性实质内肿瘤，无软脑膜侵犯。在这两种情况下 DLGNT的诊断是在DNA甲基化后进行的，这表明一例属于DLGNT类，而另一例仍未分类，但在CNV上显示了DLGNT中记录的特征性遗传发现。两种情况都携带1p / 19q编码，其中一个与KIAA1549：BRAF融合有关，而另一种与BRAF V600E和PIK3CA E545A突变有关。我们的研究扩大了DLGNTs的临床和分子谱，并指出DLGNTs的术语并不完全合适，因为某些病例既不能扩散生长，也不能分布软脑膜。这表明DLGNTs涵盖了广泛的肿瘤，尚未完全阐明。两种情况都携带1p / 19q编码，其中一个与KIAA1549：BRAF融合有关，而另一种与BRAF V600E和PIK3CA E545A突变有关。我们的研究扩大了DLGNTs的临床和分子谱，并指出DLGNTs的术语并不完全合适，因为某些病例既不能扩散生长，也不能分布软脑膜。这表明DLGNTs涵盖了广泛的肿瘤，尚未完全阐明。两种情况都携带1p / 19q编码，其中一个与KIAA1549：BRAF融合有关，而另一种与BRAF V600E和PIK3CA E545A突变有关。我们的研究扩大了DLGNTs的临床和分子谱，并指出DLGNTs的术语并不完全合适，因为某些病例既不能扩散生长，也不能分布软脑膜。这表明DLGNTs涵盖了广泛的肿瘤，尚未完全阐明。