Light Penetration Into A Six-Layer Skin Model For 200-1000 Nm

A review of proton pump inhibitor photosensitivity in a tertiary referral photodiagnostic centre S. Butt, A. McMullan, R. Dawe and S. Ibbotson Photobiology Unit, Ninewells Hospital and Medical School, Dundee, UK Over the last few years, we have seen 11 patients presenting with proton pump inhibitor (PPI) photosensitivity at our tertiary referral photodiagnostic service and in our local dermatology department. Many adverse effects, including the discovery in 2020 of an almost twofold increased risk of severe COVID19, of this widely used group of drugs have been noted (Lee SW, Ha EK, Yeniova A€ O et al. Severe clinical outcomes of COVID-19 associated with proton pump inhibitors: a nationwide cohort study with propensity score matching. Gut 2020; 70: 76–84.). Although PPI-induced phototoxicity has been described, phototest results have not been reported and all clinical presentations have not been described. We aimed to identify all patients with PPI photosensitivity who presented to our unit. We sought to better understand their clinical characteristics, blood test results and photodiagnostic results. We retrospectively reviewed all case notes and investigation results of patients who were diagnosed with PPI photosensitivity. Eleven patients were identified to have been seen between 2014 and 2019. Two patients were male and nine were female. Mean duration of disease was 3 6 years and mean duration of PPI ingestion was 5 years. Five patients presented with a drug-induced lupus pattern [subcutaneous lupus erythematosus (SCLE; n = 2), papulosquamous SCLE and discoid (n = 1), tumid (n = 1) and acute cutaneous (n = 1)], four with drug-induced phototoxicity (sunburn-like) and two with a drug-induced solar urticaria relating to a lupus mechanism. The majority of patients reported symptoms on sun-exposed sites. The most common indication for PPI prescription was gastroesophageal reflux disease with omeprazole being the most commonly prescribed PPI. All patients underwent phototesting. Three patients were not on an PPI while undergoing phototesting and did not demonstrate photosensitivity. Of the remaining patients who underwent phototesting the most common finding was delayed sensitivity to ultraviolet A and to visible light. Drug-induced photosensitivity can be a challenging diagnostic entity owing to the varied clinical presentation and heterogeneous time to onset. We present this case series to further help clinicians in recognizing the clinical and diagnostic pattern of photosensitivity present with PPI use.