Basal Layer Damage
Marked basal layer damage is a feature of Erythema multiforme and its variants Stevens Johnson syndrome and Toxic epidermal necrolysis. We call this interface reaction pattern. It may also be seen to a lessor degree in lupus erythematosus and lichen planus and in the PLEVA variant of Pityriasis lichenoides.
Older terms for these changes were liquifactive degeneration and hydropic degeneration.
Lichenoid reaction pattern may overlap here but usually gives less vacuolar changes at the DEJ than interface damage .
