Vitiligo-Like Depigmentation Induced by Cyclin-Dependent Kinase 4/6 Inhibitors in the Treatment of Metastatic Breast Cancer: A Case Report and Literature Review.

Cyclin-dependent kinase (CDK) 4/6 inhibitors are commonly used in the first-line treatment of hormone receptor-positive, human epidermal growth factor receptor 2-negative metastatic breast cancer, and more recently in the adjuvant setting as well. Whilst cutaneous toxicities are well documented, vitiligo-like depigmentation (VLD) is rarely reported in existing literature. Such adverse effects impair tolerability and compromise patients' quality of life. Here we describe a case from our centre of a 72-year-old Chinese woman with recurrent, metastatic hormone-positive breast cancer who developed a rare case of VLD after eight months of treatment with ribociclib. The development of lesions was preceded by diffuse pruritis, initially beginning on her back before eventually involving her distal limbs. Ribociclib was switched to palbociclib, which was subsequently stopped as the VLD continued to progress. She was reviewed by dermatology, with CDK 4/6 inhibitor-induced VLD as a clinical diagnosis. She was started on topical tacrolimus and mometasone cream with minimal improvement. Our case, in conjunction with the 40 cases evaluated as part of our literature review, highlights the need to increase physician awareness of VLD as a rare but significant complication of CDK 4/6 inhibitor use. Given its expanding role in everyday practice, it would be useful to recognise its typical clinical course and morphology, understand its pathophysiology and explore potential treatment options.