Spongiosis: intraepidermal edema -> hydrostatic separation of the keratinocytes, revealing the intercellular desmosomal attachments
Appears like the cut surface of a sponge
Three Defined Phases of Spongiosis
Acute Spongiosis
Subacute Spongiosis
Chronic Spongiosis
Etiology
Eczematous Dermatitides: all of these are histologically similar and can manifest any of the phases of spongiosis (depending on when they are biopsied in the course of the disease) -> therefore, clinical history is crucial to making the diagnosis