Pancreatic neuroendocrine carcinomas (NECs) are rare and very aggressive neoplasms with dismal prognosis, especially when metastatic or with negative prognostic factors, such as vascular invasion. To the best of our knowledge, no case of pancreatic NEC with mismatch repair deficiency has been reported to date. We describe a 62-year-old patient who underwent pancreaticoduodenectomy for a NEC located in the pancreatic head, with peripancreatic lymph node metastases. Tumor necrosis was prominent and the Ki67 proliferative index was 60%. One year after the diagnosis, the patient experienced recurrence with a left supraclavicular lymph node metastasis, which was surgically removed, followed by standard cisplatin-etoposide chemotherapy. Neoplastic cells showed combined loss of expression of MLH1 and PMS2 in both primary tumor and lymph node metastasis. Microsatellite instability (MSI) test using a mononucleotide repeats pentaplex PCR (BAT-25, BAT-26, NR-21, NR-22, and NR-24) revealed minimal mononucleotide shifts showing deletion of less than 3 bp at NR-21, BAT-26, NR-24, and NR-22 loci. MLH1 methylation analysis revealed absence of the gene promoter methylation. BRAF and KRAS mutations were not detected. In gut, NECs' mismatch repair deficiency phenotype has been reported in about 10% of cases, and it represents an independent factor of more favorable outcome. Likewise, our patient is currently alive with a follow-up of more than 12 years after pancreaticoduodenectomy, by itself an unexpected finding for such an aggressive neoplasm.

中文翻译：

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具有 MLH1/PMS2 免疫缺陷和最小微卫星移位的转移性错配修复缺陷型胰腺神经内分泌癌手术和化疗后的长期生存和长期缓解。


胰腺神经内分泌癌（NEC）是一种罕见且极具侵袭性的肿瘤，预后较差，尤其是当发生转移或存在血管侵犯等负面预后因素时。据我们所知，迄今为止尚未报道过具有错配修复缺陷的胰腺 NEC 病例。我们描述了一名 62 岁的患者，他因胰头 NEC 接受胰十二指肠切除术，并伴有胰周淋巴结转移。肿瘤坏死明显，Ki67增殖指数为60%。诊断一年后，患者出现左锁骨上淋巴结转移复发，经手术切除，随后接受标准顺铂-依托泊苷化疗。在原发肿瘤和淋巴结转移中，肿瘤细胞显示 MLH1 和 PMS2 表达联合缺失。使用单核苷酸重复五重 PCR（BAT-25、BAT-26、NR-21、NR-22 和 NR-24）进行的微卫星不稳定性 (MSI) 测试揭示了最小的单核苷酸位移，显示 NR-21 处删除了不到 3 bp， BAT-26、NR-24 和 NR-22 基因座。 MLH1 甲基化分析显示该基因启动子不存在甲基化。未检测到 BRAF 和 KRAS 突变。在肠道中，大约 10% 的病例中报道了 NEC 的错配修复缺陷表型，它代表了更有利结果的独立因素。同样，我们的患者在胰十二指肠切除术后经过 12 年多的随访，目前仍存活，对于这种侵袭性肿瘤来说，这本身就是一个意外的发现。