ICHTHYOSIS
What is Ichthyosis?
Ichthyosis is the term used to describe continual and widespread scaling of
the skin. It may be inherited (genetic) or acquired during life. The inherited
forms are rare and are generally present from infancy and are usually lifelong
conditions. Acquired Ichthyosis can develop at any age due to a number of
medical problems, such as kidney disease.
The commoner forms of inherited Ichthyosis are mild and do improve in the
summertime. There are a number of very rare conditions where Ichthyosis occurs
with problems in other systems of the body. Each of the major types of
Ichthyosis will be discussed briefly, followed by an outline of the management.
What is Inherited Ichthyosis?
Inherited Ichthyosis is due to a single genetic flaw which is passed on
either from one parent, or both parents, or develops as a new fault in the gene
very early in foetal life. It can be mild as with ichthyosis vulgaris, or
severe.
Ichthyosis vulgaris
This is the commonest form of inherited Ichthyosis affecting one in every
250 people. It is usually quite mild and develops in early childhood with fine,
light grey scales and roughness on the arms and legs. It may be more widespread
and is more obvious in the winter time and in temperate climates. It is
sometimes associated with atopic or childhood allergic eczema and may cause an
increased wrinkling of the palms and soles.
It can be improved with regular application of moisturisers. It improves in
adult life and may be passed on to a sufferer's children, with a risk for each
child of 50% (autosomal dominant transmission).
X-linked Recessive Ichthyosis
This condition occurs in males only and develops in infancy with tan or grey
scales on the limbs and across the trunk. It may effect the ears and face and
the scales appear to be stuck on like stamps. It varies in its severity and
improves in fine or sunny weather. It changes very little with age.
This condition is passed on by a mother, who is a carrier of the abnormal
gene, to her son with a 50% risk for each son (X-linked recessive
transmission). A carrier mother shows no evidence of the condition. The gene
that causes this condition has been identified and very rarely a similar fault
can affect adjacent genes on the same chromosome, causing a variety of other
problems for an affected male, for instance, bony defects or lack of the sense
of smell.
A mother who is carrying an affected male baby may have a prolonged and
consequently difficult labour. It is important for family members who may carry
this gene, to inform their obstetricians. A small number of affected boys have
poorly descended, or undescended testicles, it is usual to check this aspect of
development in affected families. The child's growth should be monitored from
time to time. It is quite common to have very small specks in the front of the
eye, both in the affected boy and sometimes also in the boy's mother. These do
not interfere with vision.
Congenital Ichthyosiform Erythroderma
There are two types of Ichthyosis in this category. They generally declare
themselves at birth with the appearance of a so called collodion membrane on
the newborn baby. This is a shiny, yellow film stretched across the skin like a
sausage skin. It dries out and gradually sheds within the first week of life.
The "collodion baby" is nursed in a humidified incubator until the
skin settles down. The majority of collodion babies will develop congenital
ichthyosiform erythoderma. However, a small number of these babies will have
normal skin once the membrane is shed and, therefore, it is not possible to
accurately predict the outcome in the early stages.
Most collodion babies develop non-bullous ichthyosiform erythroderma, which
literally means inflamed, scaly skin, without blisters. It affects 1 in every
300,000 births and so is quite rare. Once the collodion membrane has shed, the
skin remains red and has fine, white scales affecting all of the skin surface.
(Fig 2). In severely affected children the eyelids may be pulled outwards and
there may be some mild scalp hair loss and tightness of the fingers results.
Because the skin is inflamed it will feel hot, even if the child is cold. Most
children with this condition do not sweat normally and may overheat in hot
weather, when exercising or with a fever. The palms and soles are sometimes
thickened and scaly. Otherwise a child's health is normal. They may suffer from
cosmetic and this is especially important when a child starts school, or in the
teenage years.
The less common form of congenital ichthyosiform erythoderma is Lamellar
Ichthyosis. This is different in that the skin is less red but the scaling is
larger, perhaps darker and more adherent, or stuck down.
These two conditions are passed on by parents with normal skin who both
carry the abnormal gene (autosomal recessive) and the risk of a further child
being affected is 1 in 4. They can be diagnosed on a skin biopsy from the
foetus taken (between 18 - 20 weeks) halfway through a pregnancy, if the
parents which to know but there is no way of preventing them before conception,
as the abnormal gene has not yet been identified.
Bullous Ichthyosiform Erythroderma
Bullous ichthyosiform erythoderma, also known as bullous ichthyosis, is
another rare inherited Ichthyosis. At birth the baby's skin seems to be fragile
and may show blisters, without much scaling. This causes severe problems for
the young infant and intensive care is sometimes necessary in the first few
weeks of life. A skin biopsy will be required early on to confirm the
diagnosis. During the first year or two of life, the blistering tendency
reduces but widespread redness, scaling and thickening of the skin becomes more
obvious through childhood (Fig 3). This produces warty skin changes around the
creases of the joints. Skin infections are quite common and can lead to a
characteristic odour. There may be a reduction in sweating in childhood, which
improves later in life. This is a troublesome and distressing condition for the
child and the family.
It is transmitted as an autosomal dominant disorder, which means that one of
the parents may be affected. However, in at least half of affected children,
neither parent is affected and therefore the child has developed a new gene
fault while growing in the womb. This means that there is no risk above the
ordinary for further pregnancies in that family although the child may pass on
the condition onto the next generation. Detailed genetic counselling is
necessary.
Harlequin Ichthyosis
Harlequin Ichthyosis is a very severe, but extremely rare type of inherited
ichthyosis (approximately 3 per year in the UK). It is evident at birth because
the newborn baby looks like a harlequin costume, with very thick scaling all
over. Intensive care is required and detailed information on the condition will
be needed for the parents and staff.
Netherton's Syndrome
The incidence of this condition is not known but it is probably in the
region of 1 in each 200,000 births in the UK. The newborn child is very red and
has scaly or peeling skin. The infant is often underweight and slow to grow and
this problem continues for the first year or two of life. The affected child
may need prolonged hospital treatment until both the skin and the nutrition
improve. A characteristic feature of Netherton's syndrome is thin fragile scalp
hair in the baby. Later it is spiky and this is an important clue to the
diagnosis. In many affected children the skin improves in childhood, although
it can flare up without warning.
Netherton's syndrome is an autosomal recessive disorder where both parents
are carriers and show no sign of the condition. There is however a risk to
further babies of the order of 25%.
There are a number of other genetic or inherited forms of ichthyosis where
there are other medical problems but these are so uncommon, that they are not
discussed here.
Treatment of Ichthyosis
In the milder types of ichthyosis the main treatment is regular application
of moisturisers or emollients. A very wide selection of emollients is available
(creams, ointments, lotions, bath oils) and a person with ichthyosis should try
several different types before deciding on which is best. Parents will need to
help young children with regular moisturisers, so that they get into the habit
of applying them. Peeling creams ( keratolytics, e.g. salicylic acid) are
sometimes used but they can irritate the skin. They are helpful on the palms
and soles. There are encouraging reports of improvement with Dovonex and
similar skin preparations that were originally developed to treat psoriasis.
The rarer types of Ichthyosis with inflamed skin in the infant require
intensive medical and nursing care. For older children and adults with these
severe types of ichthyosis, a trial of retinoid (vitamin A) tablet treatment
may be suggested. Retinoids reduce the growth of over-active scaly skin and can
improve its appearance. They have little influence on the inflammation or
redness of severe inflamed Ichthyosis. Regular blood tests and checks on growth
will be needed. As retinoid treatment can severely damage an unborn baby,
pregnancy is to be avoided at all costs. Antibiotics or antiseptics may be
prescribed for skin infections but steroid treatments are not effective in
ichthyosis.
The genetics of Ichthyosis
There are so many types of inherited Ichthyosis that have different patterns
of inheritance, that parents of an infected child and, when appropriate, the
affected person will need expert genetic counselling to help them understand
the genetics of the disorder.
Research in Ichthyosis
There have been dramatic advances in the understanding of the causes of
certain inherited Ichthyosis, especially X-linked recessive ichthyosis and
bullous ichthyosis. Intensive research is ongoing and in time will lead early
diagnosis and better treatments.
Further information
A patient support group, called Ichthyosis Support Group, has been set up
and is delighted to hear from people with ichthyosis, and their families.
They can give advice, support and information on all types of inherited
Ichthyosis.
National contact
Ichthyosis Support Group
Mrs Pamelia Catlyn
16 Cambridge Court
Cambridge Avenue
Kilburn
London
NW6 5AB
 020-7461 0356 after 8 pm.
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