LEUKAEMIA, ACUTE
LEUKOPLAKIA
lymphocytic or lymphoblastic leukaemia.
If abnormal cells are derived from other
types of white cell or their precursors,
the disease is called myeloid, myelo-
blastic, or granulocytic leukaemia. (See
also
leukaemia, acute
;
leukaemia, chronic
lymphocytic
;
leukaemia, chronic myeloid.
)
leukaemia, acute
A type of
leukaemia
in which excessive numbers of immature
white blood cells called blasts are pro-
duced in the bone marrow. If untreated,
acute leukaemia can be fatal within a
few weeks or months. The abnormal
cells may be of
2
types: lymphoblasts
(immature
lymphocytes
) in acute lym-
phoblastic leukaemia, and myeloblasts
(immature forms of other types of white
cell) in acute myeloblastic leukaemia.
Exposure to certain chemicals (such
as benzene and some
anticancer drugs
)
or high levels of radiation may be a cause
in some cases. Inherited factors may also
play a part; there is increased incidence
in people with certain genetic disorders
(such as
Fanconi's anaemia
)
and chro-
mosomal abnormalities (such as
Do
'
wn
'
s
syndrome
). People with blood disorders
such as chronic myeloid leukaemia (see
leukaemia, chronic myeloid
) and primary
polycythaemia
are at increased risk, as
their bone marrow is already abnormal.
The symptoms and signs of acute
leukaemia include bleeding gums, easy
bruising, headache, bone pain, enlarged
lymph nodes, and symptoms of
anaemia
,
such as
tiredness
,
pallor, and breath-
lessness on exertion. There may also be
repeated chest or throat infections. The
diagnosis is based on a
bone marrow
biopsy
. Treatment includes transfusions
of blood and platelets, the use of
anti-
cancer drugs
,
and possibly
radiotherapy
.
A
bone marrow transplant
may also be
required. The outlook depends on the
type of leukaemia and the age of the
patient.
Chemotherapy
has increased
success rates and
6
in
10
children with
the disease can now be cured, although
treatment is less likely to be completely
successful in adults.
leukaemia, chronic lymphocytic
A
type of
leukaemia
caused by prolifera-
tion of mature
lymphocytes
. Although it
is incurable, the disease is not always
fatal. The cause is unknown.
Symptoms develop slowly, often over
many years. As well as symptoms and
signs common to acute forms of leuk-
aemia (see
leukaemia, acute
), there may
be enlargement of the
liver
and
spleen
,
persistent raised temperature, and night
sweats. Diagnosis is by blood tests and
a
bone marrow biopsy
. In many mild
cases, no treatment is needed. To treat
severe cases,
anticancer drugs
are given,
sometimes with
radiotherapy
.
leukaemia, chronic myeloid
A type of
leukaemia
, also called chronic granulo-
cytic leukaemia, which is caused by the
overproduction of granulocytes, neutro-
phils, or polymorphonuclear leukocytes
(see
blood cells
). The cause is unknown.
This type of leukaemia usually has 2
phases: a chronic phase, which may last
for several years, and a more cancerous
phase, which is known as the blastic,
accelerated, or acute phase.
During the chronic phase, symptoms
may include fever, night sweats, and
weight loss. Visual disturbances, abdom-
inal pain, and
priapism
may also occur.
The symptoms of the more cancerous
phase are like those of the acute forms
of leukaemia (see
leukaemia
,
acute)
. The
diagnosis is made from blood tests and
a
bone marrow biopsy
. Treatment of the
chronic phase includes
anticancer drugs
.
When the disease transforms into the
acute phase, treatment is similar to that
given for acute leukaemia.
leukocyte
Any type of white
blood cell
.
leukodystrophies
A rare group of in-
herited childhood diseases in which the
myelin
sheaths that form a protective
covering around many nerves are des-
troyed. These diseases cause severely
disabling conditions, such as impaired
speech,
blindness
,
deafness
, and
para-
lysis
,
and are always fatal.
leukoplakia
Raised white patches on
the
mucous membranes
of the
mouth
or
vulva
, caused by tissue thickening. It is
most common in the elderly and is
increasingly found in people with
AIDS
.
Leukoplakia in the mouth, which most
commonly occurs on the tongue, is
usually due to tobacco-
smoking
or to
rubbing by a rough tooth or denture. It
is not known what causes the condition
to develop on the vulva.
338
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