Topical simvastatin–cholesterol for disseminated superficial actinic porokeratosis: An open‐label, split‐body clinical trial

Background/Objectives Disseminated superficial actinic porokeratosis (DSAP) is a porokeratosis variant that is cosmetically disfiguring and may be associated with squamous cell carcinoma. It is an autosomal dominant condition caused by germline mutations in mevalonate pathway genes involved in cholesterol synthesis. Lesions are precipitated by ultraviolet radiation‐induced second‐hit mutations. Modulation of this pathway by topical simvastatin–cholesterol may lead to improvement. Methods This open‐label, split‐body clinical trial was carried out in 2020 at a metropolitan dermatology clinic. Eight patients contributing 13 limb pairs were recruited. Limbs within each pair were randomly allocated to 2% simvastatin/2% cholesterol cream applied twice daily or bland emollients. Lesion number, erythema, scale and patient‐reported disease activity were measured at baseline and 6 weeks. Data were analysed using Bayesian ordinal logistic regression. Odds ratios compare the odds of a higher score at 6 weeks in treated limbs with the odds in controls. Values less than one indicate improvement. Results Patients had a median age of 65 years (interquartile range [IQR] 58 to 69 years). The median baseline DLQI was 5 (range 2–21). Odds ratios were 0.12 (95% credible interval [CI] 0.01 to 0.72) for lesion number, 0.25 (95% CI 0.05 to 0.79) for erythema score, 0.18 (95% CI 0.03 to 0.64) for scale score and 0.33 (95% CI 0.09 to 0.89) for patient‐reported disease activity. Conclusions Topical simvastatin–cholesterol cream improved lesion number, erythema and scale on treated limbs compared with controls. Patient‐reported disease activity also improved. These findings warrant confirmation in blinded, vehicle‐controlled trials.