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Abstract：
OBJECTIVE: Primary mucoepidermoid carcinomas (MECs) of the sinonasal tract and nasopharynx are rare entities that represent a diagnostic challenge, especially in biopsy samples. Herein, we present a case series of MECs of the sinonasal and skull base and its mimics to evaluate the clinicopathological and molecular characteristics in order to avoid misdiagnosis.
METHODS: We reviewed the pathology records of patients diagnosed from 2014 to 2022. Thirty MECs were consecutively diagnosed during that period.
RESULTS: Based on morphological and fluorescence in situ hybridization (FISH) analyses, 30 tumors originally diagnosed as MECs were separated into MAML2 fusion-positive (7 cases) and MAML2 fusion-negative groups (23 cases), in which 14 tumors were positive for the EWSR1::ATF1 fusion; these tumors were reclassified to have hyalinizing clear cell carcinoma (HCCC). The remaining nine MAML2 FISH negative cases were reconfirmed as squamous cell carcinoma (SCC, 3 cases) which showed keratinization and high Ki-67 expression; DEK::AFF2 carcinomas (2 cases), in which DEK gene rearrangement was detected by FISH; and MECs as previously described (4 cases) with typical morphological features. Including 7 MAML2 rearrangements tumors, 11 MEC cases had a male-to-female ratio of 4.5:1, and 6 tumors arose from the nasopharyngeal region, while 5 tumors arose from the sinonasal region. The prognosis of this series of salivary gland-type MECs was favorable.
CONCLUSIONS: Our study confirmed that HCCC runs the risk of being misdiagnosed as MEC in the sinonasal tract and nasopharynx, particularly with biopsy specimens. Careful histological evaluation with supporting molecular testing can facilitate pathological diagnoses.
METHODS: We reviewed the pathology records of patients diagnosed from 2014 to 2022. Thirty MECs were consecutively diagnosed during that period.
RESULTS: Based on morphological and fluorescence in situ hybridization (FISH) analyses, 30 tumors originally diagnosed as MECs were separated into MAML2 fusion-positive (7 cases) and MAML2 fusion-negative groups (23 cases), in which 14 tumors were positive for the EWSR1::ATF1 fusion; these tumors were reclassified to have hyalinizing clear cell carcinoma (HCCC). The remaining nine MAML2 FISH negative cases were reconfirmed as squamous cell carcinoma (SCC, 3 cases) which showed keratinization and high Ki-67 expression; DEK::AFF2 carcinomas (2 cases), in which DEK gene rearrangement was detected by FISH; and MECs as previously described (4 cases) with typical morphological features. Including 7 MAML2 rearrangements tumors, 11 MEC cases had a male-to-female ratio of 4.5:1, and 6 tumors arose from the nasopharyngeal region, while 5 tumors arose from the sinonasal region. The prognosis of this series of salivary gland-type MECs was favorable.
CONCLUSIONS: Our study confirmed that HCCC runs the risk of being misdiagnosed as MEC in the sinonasal tract and nasopharynx, particularly with biopsy specimens. Careful histological evaluation with supporting molecular testing can facilitate pathological diagnoses.
摘要：
目的：鼻窦和鼻咽的原发性黏液表皮样癌（MEC）是一种罕见的诊断挑战，尤其是活检样本.在这里，我们提供了一系列的鼻腔鼻窦和颅底MECs及其模拟物，以评估其临床病理和分子特征，以避免误诊。
方法：我们回顾了2014年至2022年确诊患者的病理记录。在此期间连续诊断出30例MEC。
结果：基于形态学和荧光原位杂交（FISH）分析，将30例最初诊断为MECs的肿瘤分为MAML2融合阳性（7例）和MAML2融合阴性组（23例），其中14个肿瘤EWSR1::ATF1融合阳性;这些肿瘤被重新分类为透明透明细胞癌(HCCC)。其余9例MAML2FISH阴性病例再次确认为鳞状细胞癌（SCC，3例）显示角质化和Ki-67高表达；DEK：：AFF2癌（2例），其中通过FISH检测到DEK基因重排；如前所述的MECs（4例）具有典型的形态学特征。包括7个MAML2重排肿瘤，11例MEC病例的男女比例为4.5：1，6例肿瘤起源于鼻咽区，而5个肿瘤来自鼻窦区域。这一系列唾液腺型MEC的预后良好。
结论：我们的研究证实，HCCC在鼻窦和鼻咽部存在被误诊为MEC的风险，特别是活检标本。仔细的组织学评估与支持分子测试可以促进病理诊断。
方法：我们回顾了2014年至2022年确诊患者的病理记录。在此期间连续诊断出30例MEC。
结果：基于形态学和荧光原位杂交（FISH）分析，将30例最初诊断为MECs的肿瘤分为MAML2融合阳性（7例）和MAML2融合阴性组（23例），其中14个肿瘤EWSR1::ATF1融合阳性;这些肿瘤被重新分类为透明透明细胞癌(HCCC)。其余9例MAML2FISH阴性病例再次确认为鳞状细胞癌（SCC，3例）显示角质化和Ki-67高表达；DEK：：AFF2癌（2例），其中通过FISH检测到DEK基因重排；如前所述的MECs（4例）具有典型的形态学特征。包括7个MAML2重排肿瘤，11例MEC病例的男女比例为4.5：1，6例肿瘤起源于鼻咽区，而5个肿瘤来自鼻窦区域。这一系列唾液腺型MEC的预后良好。
结论：我们的研究证实，HCCC在鼻窦和鼻咽部存在被误诊为MEC的风险，特别是活检标本。仔细的组织学评估与支持分子测试可以促进病理诊断。
