Cutaneous Lupus Erythematosus — SCE Dermatology MCQ

Correct answer: D — Smoking

The correct answer is D, Smoking. Cigarette smoking is well recognised in UK dermatology guidance as a factor that blunts the therapeutic response to antimalarials in cutaneous lupus erythematosus (CLE), with smokers showing higher rates of treatment resistance and disease activity than non-smokers on the same hydroxychloroquine dose. The proposed mechanism includes competitive interference at the drug's site of action, altered hepatic metabolism, and enhanced pro-inflammatory pathways (dendritic cell and T cell activation) driven by tobacco constituents, all of which reduce clinical efficacy despite adequate dosing. Given this patient has active disease after 6 months of appropriately dosed hydroxychloroquine and is a current smoker, smoking cessation is the modifiable intervention most likely to restore treatment response before escalating to second line immunosuppression. Why the other options are wrong: A. Coffee intake: caffeine has no established pharmacokinetic or pharmacodynamic interaction with hydroxychloroquine and is not implicated in antimalarial treatment failure in CLE. B. High-protein diet: dietary protein does not affect hydroxychloroquine absorption, metabolism, or efficacy in lupus; there is no evidence base linking this to resistance. C. Alcohol consumption: alcohol is relevant to hepatotoxicity monitoring with other lupus therapies (e.g. methotrexate) but has no recognised effect on hydroxychloroquine's antimalarial or immunomodulatory action in skin disease. E. High BMI: obesity affects hydroxychloroquine dosing calculations (weight based dosing to limit retinal toxicity) but is not established as a cause of reduced efficacy against CLE. Key point: In any CLE patient failing to respond to adequately dosed hydroxychloroquine, actively ask about and address smoking, since it is the recognised modifiable factor that blunts antimalarial efficacy before escalating therapy.

Reference: O'Kane D, McCourt C, Meggitt S, et al. British Association of Dermatologists guidelines for the management of people with cutaneous lupus erythematosus 2021. British Journal of Dermatology 2021; 185(6): 1112-1123. https://onlinelibrary.wiley.com/doi/10.1111/bjd.20597