Prevalence and predictors of low vitamin D status in patients referred to a tertiary photodiagnostic service: a retrospective study.

Background/purpose: Low vitamin D levels have been associated with adverse effects on health. The primary source of vitamin D is cutaneous production during sunlight exposure. Sun avoidance can restrict vitamin D photosynthesis and is common practice amongst patients with photosensitivity.

Localized bullous pemphigoid induced by photodynamic therapy.

Topical photodynamic therapy (PDT) causes localized phototoxicity and has been shown both in vitro and in humans to have immunomodulatory and immunosuppressive effects. We report a case of localized bullous pemphigoid (BP) developing after PDT. Although BP has been reported to develop following cutaneous insults such as surgery, radiotherapy, psoralen ultraviolet A (PUVA) and ultraviolet B phototherapy, PDT has not previously been reported as a trigger.

A double-blind, randomized assessment of the irritant potential of sunscreen chemical dilutions used in photopatch testing.

Background: The maximum concentration of organic sunscreen filters in current usage that does not lead to irritant reactions when performing photopatch testing is not known. Such irritant reactions can be misinterpreted as positive photoallergic contact dermatitis reactions.

Objective: To determine the frequency of irritant reactions to 19 organic sunscreen filters in current use.