spongiosis

The epithelium on the margins of the ulcer shows spongiosis and there are many mononuclear cells in the basal third.

Histologic findings are nonspecific and include spongiosis and a dermal lymphohistiocytic infiltrate with eosinophils.

Clear cell acanthoma is characterized by a sharply demarcated psoriasiform epidermal hyperplasia composed of a proliferation of slightly enlarged keratinocytes, and basal cells with pale-staining glycogen-rich cytoplasm, mild spongiosis and scattered neutrophils, which may form small intraepidermal microabscesses.