[Photoallergic reactions to olaquindox in swine raisers: role of growth promotors used in feed].

BACKGROUND: The diagnosis of photodermatosis is generally facilitated by the typical localization of the eruption. The causal agent can usually be identified by history taking, allowing eviction and cure. It may be difficult to find the causal agent in cases with a sequential course. The occupational and/or recreational environment may provide helpful information. We present two cases of photodermatosis related to the occupational environment.

CASE REPORTS: A 50-year-old woman and a 29-year-old man were farm workers. both consulted for photoinduced eczema. The eczema was triggered by episodic manipulation of an antibiotic used widely for preparing animal feed. The standard allergy tests were negative. The photobiology exploration led to the diagnosis of photoallergy to olaquindox, a growth promotor added to animal feed. The course was favorable after eviction or protection against the product, providing a complementary proof of its triggering effect.

DISCUSSION: We emphasize the contribution of photobiological explorations in difficult cases with an occupational background. Generally, these patients are unaware of the composition of the products manipulated, such as feed additives.