Delayed-onset vitiligo in metastatic HR+/HER2– breast cancer during long-term ribociclib therapy.

This case highlights that cutaneous autoimmune-like toxicities, while concerning in appearance, do not necessarily warrant discontinuation of an effective anticancer drug if they are mild.Oncologists and dermatologists should be aware of CDK4/6 inhibitor-associated vitiligo, even late in the treatment timeline, and approach it with a collaborative management strategy.Moving forward, further research into the immunological or apoptotic mechanisms of this toxicity may shed light on why it occurs and how best to treat it.