I see very few biopsies that show changes of miliaria, so I thought I would post this one. The clinical diagnosis in this biopsy from the arm of an adult woman included allergic contact dermatitis, folliculitis, and bite reaction.
This biopsy showed focal spongiosis centered around an acrosyringium or intraepidermal portion of the eccrine sweat duct, with associated lymphocytic infiltrate. Not all of the acrosyringia are involved. There is some separation of the stratum corneum above this area. The superficial dermis has a mild periductal lymphocytic infiltrate with rare eosinophils. Because of the eosinophils I think allergic contact dermatitis may still be considered.