Comparison of Clinical, Histopathological, and Survival Outcomes of Pure and Mixed Mucinous Breast Carcinoma

Mucinous breast carcinoma (MBC) is a particular type of breast cancer involving the presence of extracellular mucin. MBC accounts for approximately 4% of invasive breast cancers. MBC is divided into two as pure mucinous breast carcinoma (PMBC) and mixed mucinous breast carcinoma (MMBC) according to cell cellularity ratio. We aimed to investigate the difference between MBC subtypes in terms of clinical and survival. The data of 33 patients who were operated on for MBC between January 2010 and January 2021 in our clinic were analyzed retrospectively. Demographic data, hospital admission complaints, radiological diagnostic methods, surgical technique, histopathological and immunohistochemical examination, and survival time of the patients included in the study were examined. The patients were divided into two groups, PMBC and MMBC, and compared. During the study, MBC was detected in 33 (2.16%) of 1522 patients operated on with breast cancer diagnosis in our clinic. Of the MBC patients, 23 (69.7%) were PMBC and 10 (30.3%) were MMBC. PMBC and MMBC patients were compared in clinical, histopathological, and survival. In the PMBC group, statistically significant tumor size was larger, and survival time was longer in pathological and radiological terms. In addition, axillary dissection rate and N stage were more advanced in the MMBC group. It is essential to distinguish subgroups as MMBC and PMBC according to the amount of extracellular mucin of MBC. Although PMBC is detected in larger sizes at the time of diagnosis than MMBC, MMBC has more axillary metastases and worse survival because it contains invasive components.