The following morphologic changes is most consistent with allergic, rather than irritant, contact dermatitis
Allergic form results from prior sensitization to specific allergens and  is accompanied by prominent eosinophilia, Spongiosis is common to  both allergic and non-allergic contact dermatitis.
Lymphocytic exocytosis
Papillary dermal edema
Eosinophilic infiltration
Spongiosis