A Fyad | PubMed Health

PubMed1988

Ring-shaped positive allergic patch test reactions to allergens in liquid vehicles.

In recent years, we have observed several "ring-shaped" positive allergic patch test reactions to allergens dissolved in a liquid vehicle, a more intense response at the periphery of the site of application than in the central part. The occurrence of such reactions was evaluated for formaldehyde, Kathon CG, hydrocortisone and hexamidine diisethionate. Possible explanations for such reactions include pressure and/or a capillary effect.

Allergens↗

PubMed1987

The "edge effect" with patch test materials.

A positive "edge effect", i.e., the accumulation on the skin of a chemical solution (such as fluorescein 0.01% in a 50/50 water-ethanol solution) at the periphery of the patch test sites has been demonstrated. It occurs with different test materials (Finn Chamber; Silver Patch Test; Patch Test Chamber). Practical implications are discussed: this observation could be important when discussing results of laboratory investigations. In clinical practice, it could explain the occurrence of "ring-shaped" positive allergic patch test reactions to chemicals used in solution, i.e., Kathon CG or hydrocortisone.

Humans↗