OVERVIEW

What is ichthyosis?

Ichthyosis, derived from the Greek root meaning "fish," describes a condition where the skin becomes dry and scaly, resembling fish scales or snake skin. It primarily affects the thighs, front of the calves, outer arms, chest, and back.

Ichthyosis is a genetic disorder, and the causative genes have been identified in some patients.

Currently, there is no cure for ichthyosis. Treatment mainly involves moisturizers and emollients, while severe cases may require retinoid medications.

At what age does ichthyosis typically develop?

Ichthyosis usually appears during childhood, though a small number of cases manifest at birth or shortly after.

SYMPTOMS

What are the types of ichthyosis?

Common clinical types of ichthyosis include ichthyosis vulgaris, lamellar ichthyosis, X-linked ichthyosis (also known as sex-linked ichthyosis), and epidermolytic hyperkeratosis (also known as congenital bullous ichthyosiform erythroderma).

What are the genetic characteristics of ichthyosis vulgaris?

• Ichthyosis vulgaris is the most common type, accounting for over 95% of ichthyosis cases. At least one of the patient's parents is affected.

• At least half of the patient's children may inherit the condition, sometimes up to 75%.

• The genetic trait is directly passed from the patient to their children and continues to appear in subsequent generations.

• The occurrence of the disease is not related to gender.

• The condition is generally mild and does not affect lifespan or work ability.

What are the genetic characteristics of lamellar ichthyosis?

• The patient's parents and ancestors may be unaffected, but siblings may have the same condition.

• There is a 1/4 chance that siblings will inherit the disease.

• Both males and females can be affected, with equal probability.

• The incidence is higher among the patient's parents' relatives.

• Children of consanguineous marriages have a higher risk of developing the disease.

• The occurrence of the disease is not related to gender.

• The condition is usually severe and may even be life-threatening.

What are the genetic characteristics of X-linked ichthyosis?

• X-linked ichthyosis, also known as sex-linked ichthyosis, is the second most common type.

• It occurs only in males, while females are carriers of the pathogenic gene and do not develop symptoms.

• All daughters of affected males are carriers but do not develop the disease.

• There are no geographical or racial differences in incidence.

• Symptoms appear at birth or shortly after.

• Children of consanguineous marriages have a higher risk of developing the disease.

• Affected individuals often have poor development and are smaller in stature compared to their peers.

What are the genetic characteristics of epidermolytic hyperkeratosis ichthyosis?

• Epidermolytic hyperkeratosis ichthyosis, also known as congenital bullous ichthyosiform erythroderma, is a rare type.

• At least one of the patient's parents is affected.

• At least half of the patient's children may inherit the condition, sometimes up to 75%.

• The genetic trait is directly passed from the patient to their offspring and continues in subsequent generations.

• The occurrence of the disease is not related to gender.

• The condition is generally mild and does not affect lifespan.

• Most patients develop symptoms between ages 1–5, and the disease is not gender-related.

• The skin lesions are characterized by symmetrical scaling across the body, more severe on the lower limbs than the upper limbs, worse on the front of the thighs and calves than the back, and more pronounced on the back than the abdomen. Scaling worsens in winter and improves in summer.
  In milder cases, scaling may only appear on the front of the calves without affecting other areas.

• The scales are light or dark brown, diamond- or polygonal-shaped, resembling fish scales.

What are the manifestations of lamellar ichthyosis?

• Symptoms appear at birth, affecting both males and females equally.

• At birth, the skin may be tightly wrapped in a film resembling plastic wrap. After shedding, widespread square-shaped scales with raised edges appear, resembling snake skin, as if covered in a brown-gray scaly armor, often accompanied by varying degrees of erythroderma.

• The skin lesions are characterized by extensive square-shaped scales across the body, resembling snake skin, making the body appear as if covered in brown-gray scaly armor.

What are the manifestations of X-linked ichthyosis?

• Symptoms appear at birth or shortly after, affecting only males, while females are carriers and do not develop symptoms.

• The skin lesions are characterized by prominent dark brown scales on the chest, back, nape, front of thighs and calves, and outer arms. The scales are firmly attached, often giving the face a "dirty" appearance.

• The condition does not improve with age.

What are the manifestations of epidermolytic hyperkeratosis ichthyosis?

• Symptoms appear at birth or shortly after, and the disease is not gender-related.

• The skin lesions initially present as generalized redness and blistering. The blisters have thin, fragile walls and rupture easily. After a few days, the redness subsides, and gray-brown "bumps" or "porcupine-like" scales appear in areas such as the armpits, groin, wrists, and elbows.

• The condition improves with age.

How does ichthyosis affect the body?

Most cases of ichthyosis are not severe and do not threaten life, but they significantly affect appearance. Severe cases may cause skin cracking and bleeding.

The psychological distress for patients and their families is comparable to that of other serious diseases. Many patients develop autism, social anxiety, or mental disorders.

Some patients even contemplate suicide due to the unbearable physical and emotional suffering caused by ichthyosis, and the number of such cases is increasing.

We should offer patients care, support, and understanding.

Can ichthyosis turn into cancer?

There are currently no reports of ichthyosis leading to cancer, either domestically or internationally.

CAUSES

What causes ichthyosis?

Ichthyosis is a group of inherited skin disorders caused by changes in genetic material (genes). As the name suggests, it is passed from affected parents to their children and continues to appear in subsequent generations.

Different types of ichthyosis involve different causative genes. While the specific genes responsible for some forms of ichthyosis have been identified, the genetic causes of other types remain unknown.

Is ichthyosis contagious?

Ichthyosis is a genetic skin condition, not an infectious disease. Close daily contact will not transmit the disorder.

Is ichthyosis related to seasonal changes?

The severity of scaling in ichthyosis patients varies with the seasons, typically worsening in cold, dry winters and improving in warm, humid summers.

What factors can worsen ichthyosis?

Consuming spicy or irritating foods, irregular lifestyle habits, lack of sleep, or low mood may aggravate symptoms for some ichthyosis patients. These individuals should pay special attention to maintaining a balanced diet and keeping a positive emotional state.

DIAGNOSIS

What tests are needed to diagnose ichthyosis?

Most ichthyosis patients can be diagnosed based on characteristic skin lesions, age of onset, and family history. However, a few patients require a critical skin biopsy for confirmation.

This involves taking a small piece of skin (about the size of a peanut or soybean) from the affected area, which is then processed into a specimen and examined under a microscope. This test helps differentiate ichthyosis from other skin conditions, identify the specific type of ichthyosis, and facilitate genetic counseling for the next steps.

How to distinguish hereditary ichthyosis from acquired ichthyosis?

Characteristics of acquired ichthyosis:

• Most cases are caused by systemic diseases such as lymphoma, multiple myeloma, sarcoidosis, thyroid disorders, or cancer. Symptoms typically appear months after the onset of these diseases. It can also result from drug side effects (e.g., allopurinol, niacin).
• No clear family history.
• Usually occurs at an older age.
• Symptoms improve when the underlying systemic disease resolves.

Characteristics of hereditary ichthyosis:

• Generally not associated with systemic diseases.
• Most patients have a clear family history.
• Early onset—present at birth or shortly after, or before age 5.
• Some patients experience skin improvement with age.

What is the role of genetic counseling for ichthyosis patients?

When ichthyosis patients or individuals with a family history visit a hospital offering genetic counseling, doctors conduct detailed consultations to address concerns, provide guidance, and confirm the diagnosis—whether it is monogenic or polygenic.

Diagnosing different types of ichthyosis relies on family history and pedigree analysis, combined with clinical features, genetic testing, chromosome/sex chromosome analysis, and biochemical assays.

Even after identifying the pathogenic gene, further analysis is needed to determine whether it is a new mutation or inherited from parents, which is crucial for predicting disease risk.

Thus, genetic counseling helps patients understand marriage suitability, reproductive risks, prevention strategies, and disease prognosis, making it highly important for ichthyosis patients.

Why is prenatal (in utero) diagnosis important for ichthyosis?

Prenatal diagnosis detects genetic abnormalities with high accuracy early in pregnancy. If fetal abnormalities are found, pregnancy can be terminated promptly, avoiding psychological and financial burdens for the child and family.

Are there risks associated with prenatal (in utero) diagnosis for ichthyosis?

Prenatal diagnosis for ichthyosis is an invasive procedure that may lead to miscarriage, intrauterine infection, or fetal developmental issues. It is only performed when absolutely necessary.

TREATMENT

Which department should I visit for ichthyosis?

Dermatology.

How is ichthyosis treated?

There is currently no specific cure, and the condition cannot be completely eradicated—only symptoms can be alleviated:

• Topical medications to reduce scaling, such as lactic acid, glycolic acid, pyruvic acid, calcipotriol, and tretinoin. Salicylic acid can be used for thicker scales.

• Moisturizers and emollients to prevent skin water loss. For mild cases, enhancing skin hydration can relieve symptoms.

• Newborns require intensive care and monitoring. Severe cases often need systemic retinoid therapy starting from early childhood.

How does retinoid therapy work for ichthyosis?

Common retinoids include acitretin and isotretinoin, which primarily inhibit scale formation and promote normalization of the skin, significantly improving lesions.

Patients should regularly monitor liver function and blood lipids during treatment. These drugs can cause fetal malformations and are strictly prohibited for women planning pregnancy or who are pregnant.

Can ichthyosis resolve on its own without treatment?

Ichthyosis does not resolve spontaneously.

Symptoms of ichthyosis vulgaris and epidermolytic hyperkeratosis may improve with age. Lamellar ichthyosis is present at birth and persists for life, while X-linked ichthyosis symptoms remain unchanged over time.

Does ichthyosis require hospitalization?

Most cases are not severe and can be managed through outpatient visits and regular follow-ups at reputable hospitals.

Newborns or patients with extensive skin damage may require hospitalization due to risks of dehydration, infection, or even death from compromised skin barrier function.

Can ichthyosis be completely cured?

Ichthyosis is a group of genetic skin disorders with no definitive cure. Treatment focuses on symptom relief. Patients should seek proper medical care and avoid unverified remedies.

What are the severe consequences of untreated ichthyosis?

• Dry, rough skin may cause itching, cracking, bleeding, and pain.

• Infants may develop ectropion, eclabium, restricted finger/toe movement, patchy hair loss, and scarring alopecia.

• Newborns with skin lesions risk dehydration, severe bacterial/fungal infections, and death due to impaired skin protection.

Can ichthyosis recur after treatment?

Relapse is common, and most patients require long-term or lifelong therapy.

How should pregnant patients with ichthyosis be treated?

Medication use is generally discouraged. Severe cases may require strictly supervised emollients and moisturizers.

How should breastfeeding patients with ichthyosis be treated?

Topical moisturizers and emollients can be used, avoiding application near breastfeeding areas.

DIET & LIFESTYLE

If neither spouse has ichthyosis but one has a family history of ichthyosis, can they have children?

Ichthyosis is a group of inherited skin disorders. Different types of ichthyosis have different inheritance patterns, and the risk of offspring being affected also varies.

Even if neither spouse has ichthyosis, as long as there is a family history of the condition, there is still a chance their child may develop it.

If planning to conceive, genetic counseling should be sought in advance to assess the risk of having a child with ichthyosis. Prenatal diagnosis can be performed during pregnancy, and if abnormalities are detected, termination may be considered.

What dietary precautions should be taken for ichthyosis?

• Patients with ichthyosis are advised to consume more protein-rich foods, such as eggs, milk, and fish.
• Additionally, a balanced diet is recommended, including fresh vegetables, fruits, and foods rich in vitamin A, such as carrots and animal liver.
• Recent foreign studies have reported that consuming fish oil, vitamin D, and probiotics may improve symptoms in some ichthyosis patients.

How should the skin be cared for in ichthyosis? Can cosmetics be used?

• Skin care is crucial for ichthyosis. Moisturizers should be applied daily, morning and evening—its importance is comparable to eating daily.

• Regular lukewarm baths are also recommended to increase skin hydration and soften affected areas. Avoid alkaline soaps, reduce bathing frequency in winter, keep baths short, and avoid excessively hot water. Applying moisturizers immediately after bathing helps lock in moisture.

• To minimize skin irritation, wear cotton clothing and avoid synthetic or fur-based fabrics.

• Additionally, minimize the use of cosmetics and hair dyes on affected skin to reduce exposure to potentially irritating chemicals.

PREVENTION

How to prevent ichthyosis?

Prevention of ichthyosis includes:

• Genetic counseling and related gene testing before pregnancy.

• Avoid consanguineous marriages.

• If both spouses have a family history of ichthyosis, consult a genetic specialist before pregnancy to assess the risk of the disease in offspring.

• For couples with a family history of ichthyosis, fetal genetic testing can be performed during pregnancy. If abnormalities are detected, the pregnancy can be terminated promptly.

• Pay attention to daily life and diet to avoid triggering or worsening ichthyosis. For specific precautions, refer to related questions under the [Lifestyle] section.