as Milroy’s disease. In addition, the dis-
order may occur for no known cause.
Lymphoedema may develop in the arm
following a radical mastectomy. Other-
wise, it usually causes swelling of the
legs, to an incapacitating degree in some
people. There is no known cure. Treat-
ment consists of taking diuretic drugs,
massage, wearing an elastic bandage or
compression sleeve, and special exer-
cises; these measures may bring about
some improvement.
lymphogranuloma venereumA sex-
ually transmitted disease caused by a
chlamydial infection; it is most common
in tropical areas. The first sign of this
condition may be a small genital blister
that heals in a few days. There may also
be fever, headache, muscle and joint
pains, and a rash. The lymph nodes, par-
ticularly in the groin, become painfully
enlarged and inflamed. Abscessesmay
form, and persistent ulcersmay develop,
on the skin over the affected glands.
Treatment is with antibiotic drugs.
lymphomaAny of a group of cancers in
which the cells of lymphoid tissue (found
principally in the lymph nodesand the
spleen) multiply unchecked. Lymphomas
fall into 2 categories. If certain charac-
teristic abnormal cells (Reed–Sternberg
cells) are present, the disease is called
Hodgkin’s disease. All other forms are
known as non-Hodgkin’s lymphoma.
(See Burkitt’s lymphoma;Hodgkin’s dis-
ease;lymphoma, non-Hodgkin’s.)
lymphoma, non-Hodgkin’sAny can-
cer of lymphoid tissue (found mainly in
the lymph nodesand spleen) other than
Hodgkin’s disease. In most cases there
is no known cause. Occasionally, the
disease is associated with suppression
of the immune system, particularly after
an organ transplant. One type of non-
Hodgkin’s lymphoma, known as Burkitt’s
lymphoma, is thought to be caused by
the Epstein–Barr virus.
There is usually painless swelling of
lymph nodesin the neck or groin. The
liverand spleenmay enlarge, and lym-
phoid tissue in the abdomen may be
affected. Many other organs may become
involved, leading to diverse symptoms
ranging from headache to skin ulcera-
tion. Unless it is controlled, the disease
(often marked by fever) progressively
impairs the immune system, leading to
death from infections or an uncontrolled
spread of cancer. Diagnosis is based on
a biopsy, usually taken from a lymph
node. Chest X-ray,CT scanning,MRI,
bone marrow biopsy, and lymphangiog-
raphyof the abdomen may be needed
to assess the extent of the disease.
If the lymphoma is confined to a single
group of lymph nodes, treatment con-
sists of radiotherapy. More often, the
disease is more extensive, and in such
cases anticancer drugsare given. A bone
marrow transplant, together with drug
treatment and/or radiotherapy, may be
performed on some people.
lymphosarcomaThe former name for
a condition that is now classified as a
type of non-Hodgkin’s lymphoma (see
lymphoma, non-Hodgkin’s).
lysergide see LSD.
lysisA medical term for breaking down
or destruction, usually applied to the
destruction of cells by disintegration of
their outer membrane. A common ex-
ample is haemolysis, the breakdown of
red blood cells. Lysis may be caused
by chemical action, such as that of an
enzyme, or by physical action, such as
that of heat or cold. The term lysis is
also occasionally used to refer to a sud-
den recovery from a fever.
lysozymeAn enzymefound in tears,
saliva, sweat, nasal secretions, breast
milk, and many tissues. It destroys bac-
teria by disrupting their cell walls.LYMPHOGRANULOMA VENEREUM LYSOZYME
L