No abstract

Cyclin dependent kinase (CDK) 4/6 inhibitors are targeted agents which act on cyclin-D and these combined with hormonal therapy have been approved for the treatment of locally advanced or metastatic breast cancer. CDK 4/6 inhibitors have been found to have a tolerable adverse event profile; however, they have been associated with various dermatological adverse events. We report a case of ribociclib-induced vitiligo and discuss the clinical, dermoscopic and histological features with a review of the various possible pathomechanisms involved.

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Summary Background Dipeptidyl peptidase (DPP)‐4 plays a complex role in immune regulation and its inhibition can have effects on the pathogenesis of various skin diseases. Studies have shown that DPP‐4 inhibitors are associated with an increased risk of bullous pemphigoid (BP). Aim To analyse the clinical and histopathological features of cutaneous adverse events in patients on DPP‐4 inhibitors. Methods We performed a retrospective review of patients with suspected DPP‐4 inhibitor‐associated cutaneous adverse events, at a tertiary teaching hospital from 1 January 2017 to 31 December 2020. Exclusion criteria included previous history of chronic skin disease and lack of histopathological reports or follow‐up records. The clinical characteristics, latency period, Naranjo Adverse Drug Reaction Probability Scale and clinical outcomes were evaluated. Results In total, 18 patients (10 men, 8 women; mean age 68.6 years, range 38–89 years) were included. The DPP‐4 inhibitors used were teneligliptin (n = 6), vildagliptin (n = 6), sitagliptin (n = 4), linagliptin (n = 1) and saxagliptin (n = 1). The mean interval between therapy initiation and lesion onset was 8.8 months (range 1–24 months). The dermatoses noted were BP (n = 12; 66.6%), lichenoid dermatitis (n = 4; 22.2%), psoriasiform dermatitis (n = 1; 5.6%) and spongiotic dermatitis (n = 1; 5.6%). Eight patients (44.4%) had necrotic keratinocytes as one of the distinct histological features. Causality assessment using the Naranjo scale rated the causative role of DPP‐4 inhibitors as ‘possible’ in all patients. Of the 18 patients, 11 (61.1%) noted improvement in their condition following discontinuation of DPP‐4 inhibitors, with 5 having complete remission within 6 months of stopping the drug. Conclusion DPP‐4 inhibitor‐associated dermatoses are not necessarily limited to BP. It is necessary to recognize the possibility of other dermatoses in patients on DPP‐4 inhibitors as drug substitution/cessation may improve disease morbidity.

Erythrokeratodermas are genodermatoses of keratinisation which usually presents in infancy. Erythrokeratoderma en cocardes is a rare variant of erythrokeratoderma which present as polycyclic hyperkeratotic plaques with a peripheral desquamation, forming a concentric appearance termed ‘en cocarde’. Here, we report a case of erythrokeratoderma en cocardes with onset in childhood showing excellent response after 2 months of acitretin therapy.