Resected lesions from the pineal region are rare specimens encountered by surgical pathologists, and their heterogeneity can pose significant diagnostic challenges. Here, we reviewed 221 pineal region lesions resected at New York-Presbyterian Hospital/Columbia University Irving Medical Center from 1994 to 2019 and found the most common entities to be pineal parenchymal tumors (25.3%), glial neoplasms (18.6%), and germ cell tumors (17.6%) in this predominantly adult cohort of patients. Six cases of a rare midline entity usually found exclusively in the fourth ventricle, the rosette-forming glioneuronal tumor, were identified. These tumors exhibit biphasic morphology, with a component resembling pilocytic astrocytoma admixed with variable numbers of small cells forming compact rosettes and perivascular pseudorosettes. Targeted sequencing revealed a 100% co-occurrence of novel and previously described genetic alterations in the mitogen-activated protein kinase (MAPK) and phosphoinositide 3-kinase (PI3K) signaling pathways, suggesting a synergistic role in tumor formation. The most common recurrent mutation, PIK3CA H1047R, was identified in tumor cells forming rosettes and perivascular pseudorosettes. A review of the literature revealed 16 additional cases of rosette-forming glioneuronal tumors in the pineal region. Although rare, this distinctive low-grade tumor warrants consideration in the differential diagnosis of pineal region lesions.

中文翻译：

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松果体区玫瑰花结型胶质神经元肿瘤：6例病例及文献复习

松果体区切除的病变是外科病理学家遇到的罕见标本，其异质性可能会带来重大的诊断挑战。在这里，我们回顾了 1994 年至 2019 年在纽约长老会医院/哥伦比亚大学欧文医学中心切除的 221 个松果体区域病变，发现最常见的实体是松果体实质肿瘤（25.3%）、神经胶质瘤（18.6%）和细菌在这个以成人为主的患者队列中，细胞瘤（17.6%）。鉴定了 6 例通常仅在第四脑室发现的罕见中线实体，即形成玫瑰花结的胶质神经元肿瘤。这些肿瘤表现出双相形态，其成分类似于毛细胞星形细胞瘤，混合了数量不等的小细胞，形成致密的玫瑰花结和血管周围的假玫瑰花结。靶向测序揭示了丝裂原活化蛋白激酶 (MAPK) 和磷酸肌醇 3-激酶 (PI3K) 信号通路中新的和先前描述的基因改变 100% 共同发生，表明在肿瘤形成中具有协同作用。最常见的复发突变 PIK3CA H1047R 在肿瘤细胞中发现，形成玫瑰花结和血管周围的假玫瑰花结。文献回顾显示松果体区还有 16 例形成玫瑰花结的胶质神经元肿瘤。虽然罕见，但这种独特的低级别肿瘤在松果体区病变的鉴别诊断中值得考虑。最常见的复发突变 PIK3CA H1047R 在肿瘤细胞中发现，形成玫瑰花结和血管周围的假玫瑰花结。文献回顾显示松果体区还有 16 例形成玫瑰花结的胶质神经元肿瘤。虽然罕见，但这种独特的低级别肿瘤在松果体区病变的鉴别诊断中值得考虑。最常见的复发突变 PIK3CA H1047R 在肿瘤细胞中发现，形成玫瑰花结和血管周围的假玫瑰花结。文献回顾显示松果体区还有 16 例形成玫瑰花结的胶质神经元肿瘤。虽然罕见，但这种独特的低级别肿瘤在松果体区病变的鉴别诊断中值得考虑。