[Actinic prurigo of childhood. 3 familial cases associated with HLA-DR 0407].

BACKGROUND

Actinic prurigo, as idiopathic skin reaction involving light-exposed areas, was first described in American Indians. Actinic prurigo was early considered to be a particular form at polymorphous phototoxicity, but can be identified as a specific entity on the bases of clinical features and epidemiological characteristics.

CASE REPORTS

Three children in the same family developed photosensitive reactions early in childhood with characteristic polymorphous and persistent eczema-like or papulo-nodular pruriginous lesions which predominated in light-exposed areas and appeared several hours after exposure to sun. The lesions persisted during the winter season. The lesions followed a chronic course but tended to improve at puberty. Clinical laboratory tests, serum and urine porphyrin levels and antinuclear factors were normal. Histology and photobiology explorations gave non-specific results.

DISCUSSION

These observations have three points in common with actinic prurigo observed in American Indians. HLA typing showed that our three patients, as in white patients in Great Britain, had a significant association with a specific HLA DR1 subtype: DRB10407. This DRB10407 alleles could play a role in initiating the immune response to a light-induced peptide antigen. This particular genetic predisposition, if confirmed in other studies, would be an additional argument for distinguishing actinic prurigo as a specific polymorphous phototoxicity entity.