Department of Pathology, Presbyterian Hospital, University of Pittsburgh Medical Center, PUH A616.2, 200 Lothrop Street, Pittsburgh, PA 15213, USA.
Virchows Arch. 2011 Feb;458(2):133-40. doi: 10.1007/s00428-011-1040-y. Epub 2011 Jan 18.
Several decades after a comprehensive description of mucoepidermoid carcinoma (MEC), there is no uniformly accepted grading system. The most recent debate regarding the histologic grading of MECs, centers on the wide range of reported prevalence of cyclic AMP response element-binding protein (CREB)-regulated transcription coactivator (CRTC1-MAML2) rearrangement in high-grade (HG) MECs. We hypothesize that difficulties in morphologic classification may partially explain problems in grading MECs. We believe that HG MECs, as diagnosed over the last several decades, represent a blend of true MECs with unrelated clinicopathologic entities. To examine the historic aspects of this problem, and to identify neoplasms that most commonly mimic "high-grade" MEC, we reviewed 46 cases of alleged MEC diagnosed in our department from 1956 to 1974. The diagnosis of MEC was confirmed in 22 cases and was changed in 24 cases. Compared to cases of confirmed MEC, cases with changed diagnoses had higher incidence of lymph node metastases, perineural invasion, and shorter overall survival. Adenosquamous carcinoma, squamous cell carcinoma, and salivary duct carcinoma emerged as the most common mimics of HG MEC. The single most common diagnostic issue in these cases is the level of keratinization acceptable for MEC. Twenty cases of confirmed MEC were tested for CRTC1-MAML2 rearrangement and 5 low-grade MECs, 7 intermediate grade MECs, and 2 cases of HG MEC were translocation-positive.
在对黏液表皮样癌（MEC）进行全面描述后的几十年里，目前尚无普遍接受的分级系统。最近关于 MEC 组织学分级的争论焦点是，在高级别（HG）MEC 中，环腺苷酸反应元件结合蛋白（CREB）调节转录共激活因子（CRTC1-MAML2）重排的报道率差异很大。我们假设形态学分类的困难可能部分解释了 MEC 分级的问题。我们认为，在过去几十年中诊断出的 HG MEC 代表了真正的 MEC 与无关的临床病理实体的混合体。为了检查这个问题的历史方面，并确定最常模仿“高级别”MEC 的肿瘤，我们回顾了 1956 年至 1974 年在我们科室诊断的 46 例疑似 MEC 病例。22 例被诊断为 MEC，24 例被改变诊断。与确诊的 MEC 病例相比，改变诊断的病例淋巴结转移、神经周围侵犯和总生存期更短的发生率更高。腺鳞癌、鳞状细胞癌和唾液导管癌成为 HG MEC 最常见的模拟肿瘤。在这些病例中，最常见的诊断问题是 MEC 可接受的角化程度。20 例确诊的 MEC 进行了 CRTC1-MAML2 重排检测，5 例低级别 MEC、7 例中级别 MEC 和 2 例 HG MEC 为阳性。
