Clinicopathologic significance of mucinous breast carcinoma subclassification

Abstract

Mucinous breast carcinoma is an invasive neoplasm with clusters of tumor cells floating in pools of extracellular mucin. Pure mucinous breast carcinoma needs to be differentiated from mixed mucinous breast carcinoma, also known as invasive ductal carcinoma with a mucinous component. Pure mucinous breast carcinoma can be subclassified into a hypocellular variant (type-A) and a hypercellular variant (type-B). In this study, we classified 42 cases of mucinous breast carcinoma identified in a sample of 1,041 breast carcinomas and examined the significance of the mucinous breast carcinoma subclassification. Mucinous breast carcinoma patients were more frequently hormone receptor-positive (p=0.001) and HER2 expression-negative (p=0.002) compared to non- mucinous breast carcinoma patients. The disease-free interval of mixed mucinous breast carcinoma patients was shorter than that of pure mucinous breast carcinoma patients. A multivariate logistic regression analysis showed that high nuclear grade was significantly correlated with disease-free survival (p=0.003). In this study, the mucinous breast carcinoma subclassification was found to be useful for determining appropriate treatment.