Ribociclib-induced vitiligo in a case of metastatic carcinoma of the breast

Ribociclib, a cyclin-dependent kinase 4/6 (CDK4/6) inhibitor, is commonly used to treat hormone receptor-positive (HR+), human epidermal growth factor receptor 2/neu negative (HER2/neu-) breast cancer. While effective in inhibiting cancer cell proliferation, ribociclib has been associated with various dermatologic side effects, including vitiligo. This condition, characterized by the loss of skin pigmentation, occurs due to the destruction of melanocytes. In breast cancer patients undergoing ribociclib therapy, though the exact pathophysiological mechanisms remain under investigation, a possible hypothesis suggests that the development of vitiligo may signal an immune-mediated response, potentially reflecting the drug's influence on immune modulation. This report presents a case of HR+ and HER2/neu- metastatic breast carcinoma treated with CDK4/6 inhibitor plus endocrine therapy with the development of vitiligo during the treatment.