<unk> , otherwise known as<unk>  of the breast (MCB), is a heterogeneous group of cancers that exhibit varied patterns of metaplasia and differentiation along multiple cell lines. 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. It accounts for fewer than 1% of all breast cancer diagnoses. It is most closely associated with invasive ductal carcinoma of no special type. (IDC), and shares similar treatment approaches. Relative to IDC, MCB generally has higher histological grade and larger tumor size at time of diagnosis, with a lower incidence of axillary lymph node involvement. MCB tumors are typically estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor-2 (HER-2) negative, meaning hormone therapy is generally not an effective treatment option, which correlates to a relatively poor prognosis. MCB was first recognized as a distinct pathological entity in 2000 by the World Health Organization.
Metaplastic carcinoma
Anaplastic carcinoma
Verrucous carcinoma
Adenosquamous carcinoma
Spindle cell carcinoma
Mucinous carcinoma
Adenosarcoma
Mucoepidermoid carcinoma