The presence of epithelial cells within lymph node parenchyma is typically indicative of a metastatic malignancy. However, there are rare instances in which non-neoplastic epithelial or epithelioid cells may be found within lymph nodes, either due to aberrant embryologic migration, mechanical displacement, or physiological trafficking. These can potentially lead to serious potential diagnostic pitfalls, as when such situations are encountered by surgical pathologists, there is substantial risk of overdiagnosing these as metastatic malignancy. Herein, we describe 2 cases of benign pancreatic islet cells within peripancreatic lymph nodes, and underscore the potential for misdiagnosis of this phenomenon as foci of metastatic well-differentiated neuroendocrine tumor. The benign nature of these intranodal islet cells was supported by: (1) the absence of a well-differentiated neuroendocrine tumor in the entirely submitted concomitant pancreatic resection specimen and (2) the presence of an admixture of insulin and glucagon expressing cells by immunohistochemistry in a distribution characteristic of non-neoplastic pancreatic islets. Both cases were incidental microscopic findings in pancreatic resections for intraductal papillary mucinous neoplasms that were previously biopsied and showed associated microscopic areas of fibrosis and chronic pancreatitis and thus this phenomenon may be related to mechanical displacement from prior injury and/or biopsy.

中文翻译：

---

胰周淋巴结内的良性胰岛细胞：一个潜在的诊断陷阱。


淋巴结实质内存在上皮细胞通常表明存在转移性恶性肿瘤。然而，在极少数情况下，由于异常胚胎迁移、机械移位或生理运输，可能会在淋巴结内发现非肿瘤性上皮细胞或上皮样细胞。这些可能会导致严重的潜在诊断陷阱，因为当外科病理学家遇到这种情况时，存在将其过度诊断为转移性恶性肿瘤的巨大风险。在此，我们描述了胰周淋巴结内的 2 例良性胰岛细胞，并强调了这种现象可能被误诊为转移性分化良好的神经内分泌肿瘤病灶的可能性。这些结内胰岛细胞的良性性质得到以下支持：（1）在完全提交的伴随胰腺切除标本中不存在分化良好的神经内分泌肿瘤，以及（2）通过免疫组织化学检测，存在胰岛素和胰高血糖素表达细胞的混合物。非肿瘤性胰岛的分布特征。这两起病例都是胰腺切除术中偶然发现的导管内乳头状粘液性肿瘤，之前进行了活检，并显示出相关的纤维化和慢性胰腺炎的微观区域，因此这种现象可能与先前损伤和/或活检造成的机械移位有关。