Ichthyosis is a long-term condition that results in persistently thick, dry, "fish-scale" skin. There is no cure, but a daily skincare routine usually keeps the symptoms mild and manageable.
Most people with ichthyosis have inherited a particular faulty gene from their parent. The signs and symptoms of inherited ichthyosis appear at birth or within the first year of life.
This faulty gene affects the rate at which their skin regenerates – either the shedding of old skin cells is too slow, or the skin cells reproduce at a much faster rate than they can shed old skin. Either way, this causes a build-up of rough, scaly skin.
Ichthyosis can also be acquired as an adult, caused by developing certain health conditions.
The most common type of inherited ichthyosis is ichthyosis vulgaris, which affects about 1 in 250 people. Signs and symptoms include:
skin may appear normal at birth
skin gradually becomes dry, rough and scaly, usually before the age of one
the bends of the elbows and knees and the face are not usually affected
limbs may develop fine, light grey scales
skin on the palms of the hands and the soles of the feet may have more lines than normal and be thickened
the child often also has eczema
symptoms are more obvious in the winter
Other types of inherited ichthyosis
Other inherited forms of ichthyosis are very rare and include:
X-linked ichthyosis – this only affects males and includes general scaling, particularly over the limbs, neck and buttocks
congenital ichthyosiform erythroderma – see below
harlequin ichthyosis – this is extremely rare, but the scaling is severe and requires intensive care at birth
syndromes that include ichthyosis – such as Netherton's syndrome or Sjogren-Larsson syndrome
Congenital ichthyosiform erythroderma
Ichthyosis may develop if a baby is born with a shiny yellow membrane (collodion membrane) that sheds within the first week of life. Once the membrane has shed, one of the following types of ichthyosis can develop:
non-bullous ichthyosiform erythroderma – inflamed, scaly skin affecting the entire skin surface
bullous ichthyosiform erythroderma – inflamed, scaly skin with fluid-filled blisters that may become infected and produce a foul-smelling skin odour
lamellar ichthyosis – where the skin is not as red, but the scales are larger and tighter to the skin
In severe cases of congenital ichthyosiform erythroderma, a child may also have drooping lower eyelids (ectropion), mild hair loss and tight skin on the fingers.
Acquired ichthyosis tends to develop in adulthood and is not inherited. It's usually associated with another disease, such as:
an underactive thyroid
sarcoidosis – a rare disease that causes clumps of cells to form in the organs
lymphoma – a type of cancer
Treatment and outlook
There is no cure for ichthyosis. Treatment involves moisturising and exfoliating the skin every day to prevent dryness, scaling, cracking and the build-up of skin cells.
Some of the more common forms of ichthyosis are mild and will improve in the summertime.
Your dermatologist (skin specialist) will prescribe or recommend suitable emollients, which may be a cream, ointment, lotion or bath oil.
You may find the following advice useful:
apply emollients to wet skin to trap in the moisture – ideally a few minutes after having a bath or shower
gently rub wet skin with a pumice stone to remove some of the thickened skin
brush washed hair to remove scales from your scalp
other useful exfoliating or moisturising products may include lanolin creams, products containing urea, lactic acid and other alpha hydroxy acids
Your dermatologist may recommend peeling creams, such as salicylic acid, to help exfoliate and moisturise the skin. However, some people may find these products irritate their skin.
People with severe ichthyosis may need to spend several hours a day caring for their skin. They may find they suffer the following problems:
overheating – because of a reduced ability to sweat
limited movement – because dry skin makes it too painful to move certain parts of the body
skin infection – after cracking and splitting of the skin
impaired hearing or eyesight – this is if skin builds up over the ears or eyes