Cutaneous metastases of breast cancer during adjuvant chemotherapy correlates with increasing CD44⁺/CD24⁻ and ALDH-1 expression: a case report and literature review

Cancer stem cells (CSCs) within a tumor are scarce and self-sustaining and they have the abilities for self-renewal and the potential of giving rise to diverse types of cells that compose the tumor. These cells are suggested to be associated with therapeutic failure, and therefore they remain as an important issue in this regard. We report the cases of two breast cancer patients diagnosed with rapid cutaneous metastases during adjuvant cytotoxic chemotherapy after curative mastectomy. For elucidating a relationship between CSCs and resistance to chemotherapy, we evaluated primary tumor and metastatic cutaneous lesions by CSC markers in immunohistochemical stains (CD44⁺/CD24⁻ and ALDH-1). Either CD44⁺/CD24⁻ or ALDH-1 expression increased compared to primary breast cancer during chemotherapy. This case report shows that CD44⁺/CD24⁻ or ALDH-1 expression in primary or cutaneous metastatic breast cancer may be associated with rapid onset chemoresistance.