Squamous cells are rarely found in biliary tract cytology specimens, and when present are typically scant in quantity. Over an 8-year time period, two cases at our institution reporting abundant squamous cells were identified. Both patients underwent endoscopic retrograde cholangiopancreatography with bile duct brushings and removal of a migrated biliary stent. The migrated stents were retrieved using rat toothed forceps and required removal of the endoscope through the esophagus with the stent exposed to esophageal and oral mucosa outside of the endoscope. Cytologic examination of the accompanying biliary stent material accordingly revealed abundant benign squamous cells. However, bile duct brushings showed benign ductal epithelial cells without squamous cells. Prior and subsequent cytology and bile duct surgical pathology specimens did not show squamous metaplasia. Migrated biliary stents that require endoscopic withdrawal increase the risk of contaminating samples with squamous cells. Recognition of this unique scenario is important, as the differential diagnosis includes squamous metaplasia and squamous neoplasia.

中文翻译：

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胆道细胞学中明显的鳞状细胞污染：诊断陷阱

胆道细胞学标本中很少发现鳞状细胞，即使存在，其数量也很少。在 8 年的时间里，我们机构发现了两例报告大量鳞状细胞的病例。两名患者均接受了内窥镜逆行胰胆管造影术，并进行了胆管刷洗并移除了移位的胆管支架。迁移的支架用鼠齿钳取出，需要通过食道取出内窥镜，支架暴露在内窥镜外的食道和口腔粘膜。相应的胆道支架材料的细胞学检查显示大量良性鳞状细胞。然而，胆管刷检显示无鳞状细胞的良性导管上皮细胞。之前和随后的细胞学和胆管手术病理标本均未显示鳞状化生。需要内窥镜取出的迁移胆管支架增加了鳞状细胞污染样本的风险。识别这种独特的情况很重要，因为鉴别诊断包括鳞状化生和鳞状瘤。