Department of Advanced Biomedical Sciences, Pathology Section, University of Naples Federico II, Via S. Pansini 5, 80131, Naples, Italy.
Department of Clinical Medicine and Surgery, University of Naples Federico II, Naples, Italy.
Endocr Pathol. 2018 Sep;29(3):289-293. doi: 10.1007/s12022-018-9528-5.
Grade 3 neuroendocrine tumor (NET G3) is a rare new entity that has recently been introduced in the classification of neuroendocrine neoplasms of the pancreas. It is a well-differentiated form, with a high proliferative activity (Ki67 > 20%), and it represents a category whose prognosis is intermediate between NET G2 and poorly differentiated neuroendocrine carcinoma (NEC G3). In sites other than the pancreas, this new category is by far less coded. Herein is reported a case of NET G3 of the stomach, the 13th described in literature. The patient was a 71-year-old man with a mass in the gastric fundus. Histological examination revealed a neuroendocrine tumor that was mostly composed by areas with conventional well-differentiated features and intermediate proliferative rate (< 20 mitoses/10 HPFs and 7% Ki67); part of the tumor was characterized by increased nuclear atypia, a confluent growth pattern, intermediate mitotic activity, and high Ki67 value (25%). The tumor was studied immunohistochemically and molecularly, and the only alteration that came out was MEN1 gene mutation (Lau584SerfsTer5) in both the high- and low-grade components. According to the actual classification of gastric neuroendocrine neoplasms, this case is labeled as NEC G3 but it should be named NET G3, with a much better prognosis than the former. Overall, both morphological pattern and the Ki67 value should be mentioned in the histological report in cases of high-grade neuroendocrine neoplasms because of its clinical significance in defining the prognosis and for new potential therapeutic approaches.
3 级神经内分泌肿瘤（NET G3）是一种罕见的新实体，最近在胰腺神经内分泌肿瘤的分类中被引入。它是一种分化良好的形式，具有高增殖活性（Ki67＞20%），代表了一种介于 NET G2 和低分化神经内分泌癌（NEC G3）之间的预后类别。在胰腺以外的部位，这种新类别编码的病例要少得多。本文报道了 13 例文献中描述的胃 NET G3 病例。患者为 71 岁男性，胃底部有肿块。组织学检查显示为神经内分泌肿瘤，主要由常规分化良好的区域和中等增殖率（＜20 个有丝分裂/10HPF 和 7%Ki67）组成；肿瘤的一部分特征为核异型性增加、融合性生长模式、中等有丝分裂活性和高 Ki67 值（25%）。对肿瘤进行免疫组织化学和分子研究，唯一的改变是 MEN1 基因突变（Lau584SerfsTer5），在高低级别成分中均存在。根据胃神经内分泌肿瘤的实际分类，该病例标记为 NEC G3，但应命名为 NET G3，其预后明显优于前者。总体而言，在高级别神经内分泌肿瘤的组织学报告中应提及形态模式和 Ki67 值，因为这对确定预后和新的潜在治疗方法具有临床意义。
