错配修复（MMR）基因（MLH1、MSH2、MSH6、PMS2）的生殖细胞突变可以是单等位或双等位，分别导致Lynch综合征（LS）或宪法性错配修复缺陷（CMMRD）综合征。MMR缺陷引起的胶质瘤不常见。我们描述了两例儿科高级别胶质瘤（HGG）及其伴随的MMR蛋白质缺陷患者。在组织形态学上，两例皆表现为胶质瘤，具有星形细胞形态学特征和明显的多核瘤细胞。在免疫组织化学上，第一例IDH1 p.R132H阴性，并且ATRX丧失和p53阳性。第二例IDH1 p.R132H和p53阳性，但ATRX表达仍然保持。两例病例的组织形态学以及第二例中IDH突变伴有ATRX保留，促使我们对MMR蛋白质缺陷进行免疫组织化学检测（IHC）。一例显示出适合CMMRD的免疫染色模式，而另一例则显示出适合LS的模式。两例病例在可得到的随访中对手术和放化疗都有良好的反应。我们的案例强调了在适当的临床情景、组织病理学和免疫组织化学发现下通过简单的IHC测试MMR蛋白质的重要性。识别这些肿瘤对于指导进一步的治疗和及时进行家族筛查非常重要。©2023. 作者独家授权给施普林格-弗朗格尔出版社德国分公司，施普林格自然出版集团的一部分。

Germline mutations in mismatch repair (MMR) genes (MLH1, MSH2, MSH6, PMS2) can be mono-allelic or biallelic, resulting in a Lynch syndrome (LS) or constitutional mismatch repair deficiency (CMMRD) syndrome respectively. Glioma arising in the setting of MMR deficiency is uncommon. We describe two pediatric patients with high-grade glioma (HGG) and associated MMR protein deficiency. On histomorphology both cases showed HGG with astrocytic morphology and prominent multinucleated tumor cells. On immunohistochemistry, the first case was negative for IDH1 p.R132H showed loss of ATRX and p53 positivity. The second case was positive for IDH1 p.R132H and p53, but showed retained expression of ATRX. The histomorphology in both cases and additionally IDH mutation with retained ATRX in the second case, prompted us to test for MMR protein deficiency which was carried out by immunohistochemistry (IHC). One case revealed an immunostaining pattern suggestive of CMMRD while the other was suggestive of LS. Both the cases showed good response to surgery and radio-chemotherapy in the follow-up available. Our cases highlight the importance of testing for MMR proteins by simple IHC, in the setting of appropriate clinical scenario, histopathological and immunohistochemical findings. The recognition of these tumors is extremely important to guide further treatment and prompt family screening.© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.