This rare and aggressive form of breast cancer is characterized as being composed of a mixed group of neoplasms containing both glandular and non-glandular patterns with epithelial and/or mesenchymal components.
[1] It is most closely associated with invasive ductal carcinoma of no special type (IDC), and shares similar treatment approaches.
[2] Relative to IDC, MBC generally has higher histological grade and larger tumor size at time of diagnosis, with a lower incidence of axillary lymph node involvement.
[1] Owing to its relatively recent pathological distinction, multiple classification systems have been adopted for MBC among different organizations and research groups.
The lack of consensus between these various classification systems for MBC has led to complications in both clinical practice and research studies.
Pathologic tissue diagnosis is therefore essential to distinguish MBC from other breast cancers in order to institute proper and prompt treatment.
[3] The prognosis of MBC can vary between different sub-classifications, which, given the heterogeneity of classification systems, makes assigning prognoses difficult.
Predictors associated with worse prognosis of MBC include age younger than 39 years at presentation, tumor invasion of the skin, and squamous cell carcinoma spread to the lymph nodes.