A case-control study confirmed that intraepidermal Langerhans cell collections are specifically associated with allergic contact dermatitis. This study, involving 170 skin biopsies, found the presence of Langerhans cell collections associated with an increased likelihood of allergic contact dermatitis, while heavy dermal eosinophilic infiltration was more common in non-allergic cases. The findings suggest the diagnostic utility of Langerhans cell collections in allergic contact dermatitis and emphasize the need to reconsider the specificity of dermal eosinophils as a disease marker.

Source: Journal of the American Academy of Dermatology