PD10 Objective evaluation of sunscreen in a patient with solar urticaria

Abstract Sunscreens are an important part of photoprotection for patients with photodermatoses, such as solar urticaria (SU). Despite long ultraviolet (UV)A and visible wavelength photosensitivity in many SU, sunscreens can still be beneficial (Beattie PE, Dawe RS, Ibbotson SH, Ferguson J. Characteristics prognosis idiopathic urticaria: a cohort 87 cases. Arch Dermatol 2003; 139:1149–54). However, unlike the objective assessment by monochromator phototesting, formal evaluation sunscreens’ effects is more challenging. We report 32-year-old man 2-year history immediate-onset photosensitivity, confirmed SU on action spectrum UVB, UVA light (305–460 nm). He had been using Nivea Sun SPF (sun protection factor) 50+ (Beiersdorf) reported that this increased his tolerance natural from 10 to 60 min. Based sunscreen constituents, we were surprised hear it was so effective there no mineral constituent. Therefore, evaluated testing metal halide source [Honle UVASPOT 400 T; 24.09 mW cm−2; minimal dose (MUD) < 0.13 J cm−2] through own and, comparison, Dundee Cream Beige (Tayside Pharmaceuticals) LaRoche Posay Mineral One shade 01 (L’Oreal), both which contain reflectant titanium dioxide. Three areas, measuring 15 × cm, marked out back 0.15 mL one applied each. Each area then irradiated Daavlin template multiples (1×10) MUD sites observed 30 As he severely photosensitive, none affected threshold MUD, but noted delay induction SU. offered photoprotection, occurring at min vs. 5 without 1 MUD. delayed onset min, reaction less intense most effect 50+. Urticaria intense, also 4 confirming impression clinical benefit. highlight case show how photodiagnostic employed evaluate objectively photosensitivity. Conventionally, assumed dioxide-based products, creams, required longer UVA/visible sensitivity, refinements development new may not necessarily case.