What Does "epidermis Shows Spongiosis" On Biopsy Report Suggest?

My son's biopsy report the epidermis shows spongiosis & elongation of rete pegs. The basal cell layer shows dissolution & it"s interface with the dermis is edematous with dilated capillaries & mononuclear infiltrate. Pigment incontinence & several melanophanges are seen. Mild pervascular edema & mononuclear infiltrate is seen in the deeper dermis. No granulomas are seen. There is no evidence of maligancy. Can you explain please?