Contribution of phototesting in diagnosis of photodermatoses: retrospective study of 100 cases.

Abstract

BACKGROUND\nPhotodermatoses are sun-related inflammatory skin diseases. They usually require phototesting in diagnosis. However fewer and fewer medical centers in France are equipped with photobiological equipment.\n\n\nOBJECTIVES\nThe main purpose was to evaluate the relevance of phototesting in photodermatosis diagnosis. The second goal was to study the proportions of the different kinds of photodermatosis found in this particular study.\n\n\nMETHODS\nThis study was descriptive, retrospective and mono-centric. It was based on 100 consecutive patients, who have been phototested in a French University Hospital from 2014 to 2018. Phototesting included determination of the minimal erythematous dose (MED), UVA and UVB phototests, and photopatch testing.\n\n\nRESULTS\nThe use of phototesting led to 60% of photodermatosis diagnosis and formally eliminated the latter in 13% of the cases. The diagnosis remained undetermined in 27% of the cases. Nineteen cases of polymorphous light eruption (PLE), 14 cases of photocontact dermatitis (PCD), 10 cases of solar urticaria, 8 cases of photo-aggravated atopic eczema, 5 cases of chronic actinic dermatitis and 2 cases of systemic photosensitization were diagnosed. The allergens involved in PCD were topical Non-Steroidal Anti-Inflammatory Drug (NSAID) in 9 cases, sunscreens in 3 cases, and fragrance in 2 cases. The average amount of time between the first symptoms and actual phototesting was about 7,5 years.\n\n\nCONCLUSION\nThis study confirms phototesting is truly useful. PLE was the most common form of photodermatosis, followed by PCD, and solar urticaria. As photodermatosis could imply severe diseases sometimes requiring hospitalization, it is critical to maintain this expertise.