Dermatology: Practical and Conceptual Research Letter | Dermatol Pract Concept. 2022;12(2):e2022045 1 Dermatology Practical & Conceptual Introduction Selective cyclin-dependent kinase 4/6 inhibitors (CDK 4/6i) – ribociclib, palbociclib and abemaciclib – are a novel thera- peutic option for breast cancer [1]. CDK 4/6is are well toler- ated and have shown a manageable safety profile, with mild hematological, gastrointestinal and cutaneous adverse events (AE). Vitiligo-like lesions are a dermatologic AE exception- ally reported with CDK 4/6is use [2]. Case Presentation A 70-year-old woman presented with a 6-week history of as- ymptomatic facial hypopigmented spots. For the last 8 months, she was receiving treatment with letrozole and ribociclib for a hormone receptor-positive (HR-positive) and human epider- mal growth factor receptor-2-negative (HER2-negative) met- astatic breast cancer. Dermatological examination revealed unpigmented, well-defined macules distributed symmetrically in the neck and the face, with affectation of hair follicle (Fig- ure 1, A and B). The Wood lamp examination showed bright white and sharply delineated lesions (Figure 2). Based on these findings, a diagnosis of vitiligo was made. Discussion Vitiligo is an acquired pigmentary autoimmune disorder consisting of the development of hypopigmented macules due to the selective loss of melanocytes. The cause of vitiligo remains unknown. Vitiligo-like lesions have been reported as an AE in oncological patients treated with anti-programmed death-1/ programmed death-ligand 1 (PD-1/PD-L1) im- munotherapies (pembrolizumab, nivolumab), as well as in patients treated with tyrosine-kinase inhibitors (imatinib, cabozantinib, pazopanib) [2]. It is considered an indicator of survival benefit in melanoma patients treated with an- ti-PD-1/PD-L1 immunotherapies. Selective CDK 4/6is are currently approved by the US Food and Drug Administration and the European Medicines Agency for the treatment of patients with HR-positive, HER2-negative advanced or metastatic breast cancer. Hematologic toxicity, gastrointestinal disturbances and fatigue are the most frequent side effects of this class of agents [1]. The most common der- matological adverse event is alopecia, which might be increased by the association of endocrine therapy. Moreover, pruritus and a maculopapular rash have also been reported as cutane- ous adverse reactions in patients treated with ribociclib [1,2]. Ribociclib-induced Vitiligo: a Case Report Nicolás Silvestre Torner1, Antonio Aguilar Martínez1, María José Echarri González2, Sergio Tabbara Carrascosa1, Jorge Román Sainz1, Fernando Gruber Velasco1 1 Department of Dermatology, Hospital Universitario Severo Ochoa, Leganés (Madrid), Spain. 2 Department of Oncology, Hospital Universitario Severo Ochoa, Leganés (Madrid), Spain. Key words: vitiligo, ribociclib, selective cyclin-dependent kinase 4/6 inhibitors, breast cancer, adverse event Citation: Silvestre-Torner N, Aguilar-Martínez A, Echarri-González MJ, Tabbara-Carrascosa S, Román-Sainz J, Gruber-Velasco F. Ribociclib-induced vitiligo: a case report. Dermatol Pract Concept. 2022;12(2):e2022045. DOI: https://doi.org/10.5826/dpc.1202a45 Accepted: July 29, 2021; Published: April, 2022 Copyright: ©2022 Silvestre-Torner et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License BY-NC-4.0, which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original authors and source are credited. Funding: None. Competing interests: None. Authorship: All authors have contributed significantly to this publication. Corresponding author: Nicolás Silvestre Torner, Department of Dermatology. Hospital Universitario Severo Ochoa. Avenida de Orellana. Zip code 28911. Leganés (Madrid). Spain. E-mail: nicolassilvestretorner@gmail.com 2 Research Letter | Dermatol Pract Concept. 2022;12(2):e2022045 Figure 1. (A,B) Clinical images. Achromic sharply demarcated macules in the neck, cheeks and ears, with affectation of the hair follicle. Figure 2. Clinical image. Bright white and sharply delineated le- sions showed with Wood lamp. Vitiligo-like lesions have been described in patients treated with CDK 4/6is too, mostly in relation to ribociclib [2]. Although the pathogenic mechanism between CDK 4/6is and vitiligo is still unclear, it has been classified as a class-re- lated AE. The cell-cycle arrest and consequent apoptosis in- duced by CDK 4/6is [1], may lead to a premature death of melanocytes, that clinically manifests as achromic lesions. The prognostic meaning of vitiligo lesions in patients treated with CDK 4/6is remains still unclear. Treatment of vitiligo induced by CDK 4/6i is challeng- ing. Similar therapeutic strategies followed in other vitiligo patients can be performed. However, immunosuppressants and biological therapies should be avoided in oncological patients. Partial response has been achieved with topical immunosuppressants in combination with oral corticoste- roids [2]. Conlusions Depigmentation may cause psychological distress and may decreased quality of life. Therefore, oncological patients treated with CDK 4/6is should be informed about this po- tential AE and should be referred to a dermatologist for ac- curate diagnosis and treatment. References 1. Rascon K, Flajc G, De Angelis C, Liu X, Trivedi MV, Ekinci E. Ribociclib in HR+/HER2- Advanced or Metastatic Breast Can- cer Patients. Ann Pharmacother. 2019;53(5):501–509. DOI: 10.1177/1060028018817904. PMID: 30522347 2. Sollena P, Nikolaou V, Soupos N, et al. Vitiligo-like lesions in patients with advanced breast cancer treated with cycline-dependent kinases 4 and 6 inhibitors. Breast Cancer Res Treat. 2021;185(1):247-253. DOI: 10.1007/s10549-020-05914-w. PMID: 32914354.