BACKGROUND & AIMS Lynch syndrome is characterized by DNA mismatch repair (MMR) deficiency. Some patients with suspected Lynch syndrome have DNA MMR deficiencies but no detectable mutations in genes that encode MMR proteins-this is called Lynch-like syndrome (LLS). There is no consensus on management of patients with LLS. We collected data from a large series of patients with LLS to identify clinical and pathology features. METHODS We collected data from a nationwide-registry of patients with colorectal cancer (CRC) in Spain. We identified patients whose colorectal tumors had loss of MSH2, MSH6, PMS2, or MLH1 (based on immunohistochemistry), without the mutation encoding V600E in BRAF (detected by real-time PCR), and/or no methylation at MLH1 (determined by methylation-specific multiplex ligation-dependent probe amplification), and no pathogenic mutations in MMR genes, BRAF, or EPCAM (determined by DNA sequencing). These patients were considered to have LLS. We collected data on demographic, clinical, and pathology features and family history of neoplasms. The χ2 test was used to analyze the association between qualitative variables, followed by the Fisher exact test and the Student t test or the Mann-Whitney test for quantitative variables. RESULTS We identified 160 patients with LLS; their mean age at diagnosis of CRC was 55 years and 66 patients were female (41%). The Amsterdam I and II criteria for Lynch syndrome were fulfilled by 11% of cases and the revised Bethesda guideline criteria by 65% of cases. Of the patients with LLS, 24% were identified in universal screening. There were no proportional differences in sex, indication for colonoscopy, immunohistochemistry, pathology findings, or personal history of CRC or other Lynch syndrome-related tumors between patients who met the Amsterdam and/or Bethesda criteria for Lynch syndrome and patients identified in universal screening for Lynch syndrome, without a family history of CRC. CONCLUSIONS Patients with LLS have homogeneous clinical, demographic, and pathology characteristics, regardless of family history of CRC.

中文翻译：

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Lynch样综合征的临床和病理特征。

背景和目的 Lynch 综合征的特征是 DNA 错配修复 (MMR) 缺陷。一些疑似林奇综合征的患者存在 DNA MMR 缺陷，但在编码 MMR 蛋白的基因中没有可检测到的突变——这被称为林奇样综合征 (LLS)。对 LLS 患者的管理尚无共识。我们收集了大量 LLS 患者的数据，以确定临床和病理特征。方法我们从西班牙的全国性结直肠癌 (CRC) 患者登记处收集数据。我们确定了结直肠肿瘤缺失 MSH2、MSH6、PMS2 或 MLH1（基于免疫组织化学）、BRAF 中没有编码 V600E 的突变（通过实时 PCR 检测）和/或 MLH1 没有甲基化（通过甲基化确定）的患者。 -特异性多重连接依赖性探针扩增），MMR 基因、BRAF 或 EPCAM（通过 DNA 测序确定）中没有致病性突变。这些患者被认为患有 LLS。我们收集了关于人口统计学、临床和病理学特征以及肿瘤家族史的数据。χ2 检验用于分析定性变量之间的关联，其次是Fisher精确检验和St​​udent t检验或Mann-Whitney检验用于定量变量。结果 我们确定了 160 名 LLS 患者；他们诊断为 CRC 时的平均年龄为 55 岁，66 名患者为女性（41%）。11% 的病例符合阿姆斯特丹 I 和 II 标准，65% 的病例符合修订后的 Bethesda 指南标准。在 LLS 患者中，24% 在普遍筛查中被发现。性别、结肠镜检查指征、符合阿姆斯特丹和/或 Bethesda 林奇综合征标准的患者与在林奇综合征普遍筛查中确定的患者之间的 CRC 或其他林奇综合征相关肿瘤的免疫组织化学、病理结果或个人病史，没有 CRC 家族史。结论 无论 CRC 家族史如何，LLS 患者具有均一的临床、人口统计学和病理学特征。