Myoepithelial differentiation in breast carcinoma

Area of Science:

• Oncology
• Pathology
• Breast Cancer Research

Background:

• Describes a rare matrix-producing carcinoma with anaplastic myoepithelial cell foci.
• Highlights the coexistence of in situ myoepithelial carcinoma originating from sclerosing adenosis.

Observation:

• A 51-year-old woman presented with a breast lump, diagnosed as malignancy after biopsy.
• Histological examination revealed a tumor within a sclerosed fibroadenoma and sclerosing adenosis, featuring invasive carcinoma and carcinoma in situ.

Findings:

• Immunohistochemistry showed both invasive and in situ components were positive for CK7, CK19, CK14, vimentin, smooth muscle actin, nerve growth factor receptor, and epidermal growth factor receptor.
• CK5/6 was positive only in the in situ component, while p63 and CD10 were negative.
• bcl-2 was positive in some invasive tumor cells, and p53 was positive in both invasive and in situ components.

Implications:

• The combined histopathological and immunohistochemical profile supports a myoepithelial cell origin for this tumor.
• This case contributes to understanding the spectrum of myoepithelial-derived breast neoplasms.
• Further research into myoepithelial cell differentiation in breast cancer is warranted.