[Hydroa vacciniforme--urocanic acid content of the horny layer of the epidermis]. / Hidroa vacciniformia--Urokaninsäuregehalt der Hornschicht.

Urocanic acid was measured by means of high-performance liquid chromatography (HPLC) in the stratum corneum of a 3.5-year-old child suffering from hidroa vacciniformia. Compared to ten healthy children of equal age, the urocanic acid content of the stratum corneum was reduced significantly. In addition, there was an elevated level of some amino acids in the urine, particularly that of histidine and methylhistidine, which seems to be a very important finding. Urocanic acid acts as a natural sun protective agent, and the results are discussed with this in mind. It was not possible to elicit hidroa vacciniformia lesions in the patient by UV-A, as described by others.