富含细胞外黏液的唾液腺肿瘤诊断及鉴别诊断OA

This paper systematically elaborates on the key points of diagnosis and differential diagnosis of salivary gland tumors characterized by a substantial amount of extracellular mucus as a main or prominent feature,and clarifies the core differential features.The term"mucus-rich"specifically denotes that mucus is a major component of the tumor,rather than a focal or minor one.This phenomenon is associated with distinct histogenetic mechanisms:it may result from specific genetic mutations(e.g.,AKT1 E17K in mucinous adenocarcinoma)that drive ductal epithelial differentia-tion into mucus-secreting cells,or from myoepithelial cells secreting glycosaminoglycans that form a myxoid stroma.Salivary gland tumors with abundant extracellular mucus include mucinous cystadenoma,sialadenoma papilliferum-like intraductal papillary tumors,mucinous myoepithelioma,pleomorphic adenoma with mucin-rich stroma,mucinous adeno-carcinoma,low-grade mucoepidermoid carcinoma,mucin-rich salivary duct carcinoma and intestinal-type adenocarci-noma.The diagnosis of these tumors is complicated by the dual nature of extracellular mucus:while it is a defining fea-ture of some entities,it can also obscure key diagnostic architectural features in others,leading to histological overlap and inconspicuous diagnostic areas.Given the frequent histological morphological overlap among these tumors,immuno-histochemical findings and molecular characteristics have emerged as crucial differential diagnostic criteria.Core differ-ential diagnostic points include the following:histologically,there must be meticulous identification of typical structures obscured by mucin(such as squamoid cells in mucoepidermoid carcinoma and apocrine features in salivary duct carci-noma);in immunohistochemical staining,CK20 is useful for distinguishing intestinal-type adenocarcinoma(positive)from mucinous adenocarcinoma(negative),while androgen receptor aids in differentiating salivary duct carcinoma(posi-tive)from mucoepidermoid carcinoma(negative);and molecular testing plays a critical role in definitive diagnosis(e.g.,the AKT1 E17K mutation for mucinous adenocarcinoma,MAML2 rearrangement for mucoepidermoid carcinoma,and MEF2C::SS18 fusion for microsecretory adenocarcinoma).This paper systematically summarizes the core pathological features and differential diagnostic points of mucin-rich salivary gland tumors,aiming to provide a practical reference for clinical pathological diagnosis.