ConditionSkin, hair & nails
Ichthyosis
Ichthyosis is a group of skin conditions that cause persistently dry, thickened, scaly skin, named after the Greek word for fish. The most common form, ichthyosis vulgaris, is inherited, affects about 1 in 250 people, and causes fine white or gray scales mainly on the shins, with dry, lined palms. Rarer inherited forms can be severe from birth. Ichthyosis can also be acquired in adulthood with thyroid disease, lymphoma or some medicines. There is no cure, but daily moisturizing and exfoliating keep skin comfortable.
Also called: Fish scale disease, ichthyosis vulgaris, disorders of cornification
At a glance
- What it is
- A group of conditions where skin cells build up into dry scales.
- Most common
- Ichthyosis vulgaris, from filaggrin gene changes.
- Other types
- X-linked, lamellar, congenital ichthyosiform erythroderma, harlequin, epidermolytic.
- Acquired causes
- Thyroid disease, lymphoma, kidney disease, HIV, some medicines.
- Treatment
- Daily emollients, urea or lactic acid creams, bathing routines, retinoids for severe forms.
When to get help
Call 911 or go to the ER
- A newborn encased in a tight, shiny membrane or with thick plates of skin (collodion or harlequin baby), with feeding or breathing difficulty
- A baby with widespread red, peeling skin who is feverish, floppy or not feeding
See a doctor within a day or two
- Cracked skin with spreading redness, warmth, pus or fever (possible infection)
- Overheating, dizziness or confusion in hot weather (reduced sweating)
Book a routine appointment
- Persistent dry, scaly skin on the legs and arms that does not respond to moisturizers
- New ichthyosis-like scaling in an adult with no previous history, especially with weight loss or night sweats
- Eye irritation or reduced vision in someone with ichthyosis
Usually safe to manage at home
- Mild winter-worse scaling on the shins in someone with known ichthyosis vulgaris
What happens in the skin
The outer layer of skin normally renews itself by shedding dead cells invisibly. In ichthyosis, gene changes or other factors either cause skin cells to be produced too fast or prevent them from separating and shedding. The cells build up into visible scales, and the skin barrier holds water poorly, making skin dry, tight and prone to cracking.
Types of ichthyosis
| Type | Inheritance | Onset | Features |
|---|---|---|---|
| Ichthyosis vulgaris | Autosomal semi-dominant (filaggrin gene) | Infancy or childhood | Fine light scales on shins and back, spares skin folds; lined palms; often with eczema and keratosis pilaris |
| X-linked recessive | X-linked (STS gene) | Infancy, males | Larger dark brown scales on neck, trunk and limbs; corneal opacities; undescended testes in some |
| Lamellar ichthyosis | Autosomal recessive | Birth (collodion baby) | Large, dark plate-like scales; eyelids turned out |
| Congenital ichthyosiform erythroderma | Autosomal recessive | Birth | Red skin with fine white scales |
| Harlequin ichthyosis | Autosomal recessive | Birth | Very thick plates of skin; life-threatening in the newborn period |
| Epidermolytic ichthyosis | Autosomal dominant | Birth | Blistering at birth, then thick, ridged scales |
| Acquired ichthyosis | Not inherited | Adulthood | Scaling linked to underlying disease or medicines |
Some types are part of wider syndromes, such as Netherton syndrome or Sjögren-Larsson syndrome.
Symptoms
- dry, rough skin with fine to thick scales
- scales most obvious on the shins, arms and back
- itching, especially in dry weather
- deep lines on the palms and soles
- cracking and painful fissures on heels and hands
- worse in winter and cold, dry climates, better in summer and humidity
- reduced sweating and heat intolerance in more severe types
Acquired ichthyosis
Ichthyosis appearing for the first time in adulthood should prompt a search for a cause:
- Hodgkin and other lymphomas
- underactive thyroid
- chronic kidney disease
- HIV infection
- sarcoidosis
- malnutrition
- medicines such as some cholesterol drugs, kinase inhibitors and kava
Diagnosis
Most cases are diagnosed by appearance and family history. Further tests may include:
- skin biopsy
- genetic testing, especially for congenital forms
- blood tests for thyroid function, kidney function, and for acquired causes
- steroid sulfatase test for X-linked ichthyosis
- eye examination in X-linked and severe types
Treatment
Daily skin care
- Moisturize at least twice a day, ideally within 3 minutes of bathing, with thick creams or ointments.
- Keratolytic creams loosen and remove scale: urea (10% to 40%), lactic acid, glycolic acid, or salicylic acid. Avoid salicylic acid on large areas in young children because it can be absorbed.
- Bathe in lukewarm water, adding bath oil; soak to soften scale and gently remove it with a soft cloth or pumice.
- Humidifier in dry months.
- Avoid harsh soaps and very hot showers.
Prescription treatment
- Topical retinoids for thickened areas.
- Oral retinoids (acitretin, isotretinoin) for severe inherited forms; they need monitoring and are not used in pregnancy.
- Antibiotic or antifungal treatment for skin infections.
- Eye drops and eye care for eyelid problems.
Other care
- watch for overheating: cool clothing, fans and fluids
- newborns with collodion or harlequin presentation need specialized neonatal intensive care
- ear cleaning may be needed for scale buildup in ear canals
- psychological support for the effects on appearance and self-esteem
Outlook
Ichthyosis vulgaris is usually mild and often improves with age and in summer. Severe congenital forms need lifelong care but many people lead full lives. Research into targeted treatments for specific gene defects is ongoing.
Frequently asked questions
What causes ichthyosis?
Most cases are inherited and caused by gene changes that affect how skin cells form and shed. The most common, ichthyosis vulgaris, results from changes in the filaggrin gene. Acquired ichthyosis can develop in adults with thyroid disease, lymphoma, kidney disease or certain medicines.
Is ichthyosis the same as eczema?
No, but they are linked. Ichthyosis vulgaris and atopic eczema share a common gene, filaggrin, and often occur together. Eczema causes inflamed, itchy red patches, while ichthyosis causes persistent dry scaling, usually without much inflammation.
Can ichthyosis be cured?
There is no cure for inherited ichthyosis, but it can be well controlled. Daily moisturizers, creams with urea or lactic acid, and good bathing habits greatly improve the skin. Severe forms may need oral retinoids. Acquired ichthyosis may improve when the cause is treated.
Is ichthyosis contagious?
No. Ichthyosis is a genetic or acquired skin condition and cannot be caught from or spread to other people.
Sources
This guide was written from current patient and clinical guidance, including:
- American Academy of Dermatology: Ichthyosis vulgaris
- Foundation for Ichthyosis and Related Skin Types (FIRST): Types of ichthyosis
- MedlinePlus Genetics: Ichthyosis vulgaris; X-linked ichthyosis
- NHS: Ichthyosis
- National Organization for Rare Disorders: Ichthyosis