What is eczema?

Introduction
The term ‘eczema’ is used for a group of conditions that show a
similar pattern of changes in the skin, giving rise to specific changes
on the surface. The word itself comes from the Greek and means
‘to boil or flow out’ – anyone who has had acute eczema will
understand how appropriate this is.
In acute (short-term) eczema, intense inflammation leads to the
formation of little blisters (vesicles) in the skin, which soon burst
or are scratched open, leading to weeping and the ‘flowing out’ of
fluid. Even if there are no vesicles, a section of skin affected by
eczema looked at under a microscope shows fluid between the
skin cells, tending to push them apart. This produces an appearance
reminiscent of a sponge – hence the term ‘spongiosis’ that is used
by doctors. All the different conditions called eczema would be
expected to show this spongiosis, together with some degree of
inflammation around superficial blood vessels, which are dilated,
producing the hot, red feeling and appearance.