although fungal infections can cause
are an important
cause of liver abscesses (see
Infectious organisms usually reach
internal organs via the bloodstream, or
they penetrate tissues under the skin
through a wound.
An abscess may cause pain, depending
on where it occurs. Most larger absces-
ses cause fever, sweating, and malaise.
Those that are close to the skin often
cause obvious redness and swelling.
Antibiotics, antifungal drugs,
appropriate. Most abscesses also need
to be drained (see
in some cases a tube may be left in
place to allow continuous drainage.
Some abscesses burst and drain spon-
within a vital organ damages enough
surrounding tissue to cause permanent
loss of normal function, or even death,
abscess, dental A pus-filled sac in the
tissue around the root of a tooth. An
invade the pulp (the tissues in the cen-
tral cavity of a tooth) as a result of
which destroys the tooth's
enamel and dentine, allowing bacteria
to reach the pulp. Bacteria can also gain
access to the pulp when a tooth is
injured. The infection in the pulp then
spreads into the surrounding tissue to
form an abscess. Abscesses can also
bacteria accumulate in pockets that
form between the teeth and gums.
The affected tooth aches or throbs,
extremely painful. The gum around the
tooth is tender and may be red and
swollen. An untreated abscess eventu-
ally erodes a sinus (channel) through
the jawbone to the gum surface, where
it forms a swelling known as a gumboil.
As the abscess spreads, the glands in
the neck and the side of the face may
become swollen, and fever may develop.
Treatment may consist of draining the
abscess, followed by
of the affected tooth, but in some
of the tooth is neces-
are prescribed if the
infection has spread beyond the tooth.
An abscess in a periodontal pocket can
usually be treated by the dentist scrap-
ing away infected material.
absence In medical terms, a temporary
loss or impairment of consciousness
that occurs in some forms of
mal) seizures in childhood.
absorption The process by which flu-
ids or other substances are taken up by
body tissues. The term is commonly
applied to the uptake of the nutrients
from food into blood and lymph from
the digestive tract. The major site of
absorption is the small intestine, which
is lined with microscopic finger-like
projections called villi (see
villi greatly increase the surface area of
the intestine, thereby increasing the
rate of absorption.
acanthosis nigricans A rare condition
in which thickened dark patches of skin
appear in the groin, armpits, neck, and
other skin folds. The condition may
occur in young people as a genetic dis-
order or as the result of an endocrine
disorder such as
also occurs in people with carcinomas
of the lung and other organs.
Pseudoacanthosis nigricans is a much
more common condition, usually seen
in dark-complexioned people who are
overweight. In this form, the skin in fold
areas is both thicker and darker than the
surrounding skin, and there is usually
excessive sweating in affected areas. The
condition may improve with weight loss.