Panniculitis during BRAF inhibitor and/or MEK inhibitor therapy: A new case report and literature review

Introduction. - BRAF inhibitors MEK inhibitors can cause panniculitis. Since the initial case described in 2012 by Zimmer et al., some sixty further cases have been reported. Based on a clinical study and a recent and complete review of the literature, we set out in detail the characteristics of panniculitis occurring during BRAF and MEK inhibition therapy as well as the treatment thereof. Patients and methods. - A 25-year-old-patient followed for multi-metastatic melanoma and taking dabrafenib and trametinib consulted for the appearance, twenty-two days after the start of targeted therapy (TT), of panniculitis of the legs and forearms possibly induced by the TT after other causes had been ruled out. The TT had been continued following dose reduction and corticoid therapy for ten days, and complete resolution occurred after fifteen days. Results. - Fifty-three cases of panniculitis during BRAF +/- MEK inhibition therapy were analysed. The condition occurred mainly with BRAF inhibitors alone (especially vemurafenib), but it was also described with three combinations of BRAF and MEK inhibitors, regardless of age (median: 45 years), with a M/F ratio of 0.51, and in 50 % of cases, it occurred within the first month (time to onset: between 1 and 480 days). Non-specific biopsy is useful to rule out differential diagnoses. Symptomatic anti-inflammatory treatment, whether systemic or topical, may be given. In the absence of signs of severity, the TT may be continued. Conclusion. - When panniculitis occurs during BRAF +/- MEK inhibitor therapy, the causal role of the TT must be considered after full etiological investigation. It is essential to determine whether a causal relationship exists in order to avoid unwarranted cessation of treatment. (C) 2020 Elsevier Masson SAS. All rights reserved.