Department of Pathology and Molecular Diagnostics, Graduate School of Medical Sciences, Nagoya City University, Nagoya, Japan.
Department of Maxillofacial Surgery, School of Dentistry, Aichi-Gakuin University, Nagoya, Japan.
Histopathology. 2022 Mar;80(4):729-735. doi: 10.1111/his.14586. Epub 2021 Dec 14.
To investigate the histological diversity of salivary mucoepidermoid carcinoma (MEC), its clinicopathological features, and its associations with CRTC1/3-MAML2 fusions.
Salivary MEC cases (n = 177) were examined for CRTC1/3-MAML2 fusions, histological variants were classified, and tumours were graded according to four different grading systems. Adverse histological features considered to be unusual in MEC were also investigated. Of the 177 MEC cases, 110 were positive for CRTC1/3-MAML2 fusions. The classical variant was the most frequent in the fusion-positive case group, the fusion-negative case group, and the total case group. The clear/oncocytic variant was the second most frequent in the fusion-positive and total case groups. Oncocytic, Warthin-like and spindle variants were seen in the fusion-positive case group only. Clear cell, sclerosing, mucinous and central variants were seen in both the fusion-positive case group and the fusion-negative case group. No case was classified as a ciliated variant, as a mucoacinar variant, or as a high-grade transformation. As compared with the classical variant, non-classical variants were characterised by frequent CRTC1/3-MAML2 fusions and a low clinical stage in all cases. Of the four histological features considered to be unusual in MEC, marked nuclear atypia, frequent mitoses (>10/10 high-power fields) and extensive necrosis were found independently of the fusion status, and were present in 3-5% of all cases. However, none of the cases showed overt keratinisation. On comparison, the Armed Forces Institute of Pathology and modified Healey grading systems downgraded tumours, the Brandwein system upgraded tumours, and the Memorial Sloan Kettering system provided a moderate means of assessment.
Recognition of the histological diversity of MEC, its clinicopathological features and its associations with CRTC1/3-MAML2 fusions is helpful for an accurate diagnosis of this carcinoma.
研究唾液黏液表皮样癌（MEC）的组织学多样性、临床病理特征及其与 CRTC1/3-MAML2 融合的关系。
对 177 例唾液 MEC 病例进行 CRTC1/3-MAML2 融合检测，分类组织学变异型，并根据四种不同的分级系统对肿瘤进行分级。还研究了被认为在 MEC 中不常见的不良组织学特征。在 177 例 MEC 病例中，有 110 例为 CRTC1/3-MAML2 融合阳性。在融合阳性病例组、融合阴性病例组和总病例组中，经典变异型最为常见。在融合阳性和总病例组中，透明/嗜酸细胞变异型为第二常见。仅在融合阳性病例组中可见嗜酸细胞、沃辛样和梭形变异型。透明细胞、硬化、黏液和中央变异型在融合阳性病例组和融合阴性病例组中均可见。无病例被归类为纤毛变异型、黏液腺变异型或高级别转化。与经典变异型相比，所有病例中，非经典变异型均具有频繁的 CRTC1/3-MAML2 融合和较低的临床分期。在被认为在 MEC 中不常见的四个组织学特征中，明显的核异型性、频繁的有丝分裂（>10/10 高倍视野）和广泛坏死独立于融合状态，存在于所有病例的 3-5%。然而，没有病例表现出明显的角化。相比之下，武装部队病理研究所和改良希利分级系统降低了肿瘤分级，布兰德温系统提高了肿瘤分级，纪念斯隆凯特琳系统提供了一种适度的评估方法。
认识 MEC 的组织学多样性、临床病理特征及其与 CRTC1/3-MAML2 融合的关系有助于准确诊断这种癌。
