What is Ichthyosis?

Ichthyosis is a group of hereditary keratosis skin diseases, mainly manifested as dry skin. Accompanied by fish scale desquamation. The disease mostly occurs in children, mainly manifested as dry, rough skin on the extremities of the extremities or trunk, accompanied by rhombus or polygonal scales, with fish-like or snake-skin appearance. Cold and dry seasons worsen, and warm and humid seasons ease. Easy to relapse. Multi-line genetic factors cause abnormal proliferation and differentiation of epidermal cells, leading to increased cell proliferation and / or decreased cell shedding.

Basic Information

nickname

Ringworm

English name

ichthyosis

Visiting department

dermatology

Multiple groups

child

Common causes

Multi-line genetic factors

Common symptoms

Mainly as dry skin with fish scale desquamation

Contagious

no

Causes of ichthyosis

Ichthyosis vulgaris

It is an autosomal dominant genetic disease with incomplete penetrance. At present, it is thought that the mRNA is unstable and the post-transcriptional control mechanism is defective.

2. Sex-linked recessive ichthyosis

Stealth inheritance for X chromosome linkage. Deletion or mutation of the steroid sulfatase gene (STS) results in the accumulation of cholesterol sulfate. The stratum corneum cells are tightly bound and cannot fall off normally, forming scales.

3. Lamellar ichthyosis

Autosomal recessive. The gene maps multiple sites, including 2q33-35, 19p12-q12, and 14q11TGM1 gene mutations, deletions or insertions, to cell adhesion and cell membrane protein cross-linking defects.

4. Epidermolytic keratosis ichthyosis

It is an autosomal dominant genetic disease. Pathogenic genes are related to mutations in the keratin 1 (K1) and keratin 10 (K10) genes, leading to defects in keratin synthesis or degradation, affecting the normal arrangement and function of tension microfilaments in the keratinocytes of the basal layer, and thereby causing keratinization Abnormal and epidermal lysis.

5. Congenital Non Bullous Ichthyosis-like Erythema

It is autosomal recessive and is caused by mutations in multiple genes such as the lipoxygenase 12 (R) (ALOX12B) gene and the lipid oxidase 3 (ALOXE3) gene.

6. Alternate linear ichthyosis

It is an autosomal recessive disease and is caused by a mutation in the serine protease inhibitor Kazal5 (SPINK5) gene on chromosome 5p32.

Clinical manifestations of ichthyosis

1. Autosomal dominant hereditary ichthyosis vulgaris

This type is a common mild ichthyosis. If one or both of the parents are sick, there are often patients in the family, but there is no gender difference. Symptoms often develop from infancy, and symptoms ease or disappear in adulthood. Skin lesions vary in severity, with light skin only in winter, no obvious scales, and powdery flakes after scratching. In common, in addition to dry skin, gray-brown or dark brown rhombic or polygonal scales can be seen, with a fixed center and free edges.

The disease is mostly symmetrically distributed on the extremities of the extremities and the trunk, especially the elbows and knees. Flexion can also occur, often with follicular keratinous damage on the back of the hand, accompanied by hyperkeratosis of the palmoplantar. Generally face, scalp, elbow fossa, armpit, gill fossa, vulva, and gluteal cleft are often not violated. Heavier in winter and lighter in summer. Patients often have ectopic constitutions, such as hay fever and asthma.

2. Sex-linked genetic ichthyosis vulgaris

Rarely. Because the disease's genes are on the X chromosome, almost all of them are male, and more than 3 months after birth. The skin lesions are slightly different from the upper ones. The scales are large and prominent. They are yellow-brown or stained black with large fish scales. The skin is dry and rough. The skin lesions can be localized or widespread. , It is limited to the front of the ear and the face. The axillary and elbow sockets in early childhood can also be affected, the popliteal sockets in adulthood can be affected, the neck is most affected, and the abdomen of the trunk is more severe than the back. Keratosis of the hair follicles generally does not occur. The palms and skins are normal. Lighten up in summer. Skin lesions do not decrease with age, but sometimes increase dramatically. The corneal posterior wall and posterior elastic layer film may have small turbid spots, which does not affect vision. May have cryptorchidism, skeletal abnormalities, etc.

3. Epidermolytic keratosis ichthyosis

Also known as bullous ichthyosis-like erythroderma, clinically rare. At birth or within a few hours after birth, generalized erythema scales appeared. After the scales fell off, the whole body was red skin, widely distributed bullae, and there was no scar after the blisters healed. With age, the blister and red skin gradually reduced and subsided, manifested by excessive verrucous keratosis, especially the elbow socket, popliteal socket, axillary socket, groin and other flexion and intercalation sites.

4. Lamellar ichthyosis

It is an autosomal recessive and is very rare. After birth, the whole body is tightly wrapped with a wide layer of collodion-like film. After 2 to 3 weeks, the film falls off, and the skin shows extensive chronic flushing, with gray-brown quadrangular or diamond-shaped large scales, fixed at the center, and edges. free. It often occurs symmetrically on the trunk and limbs of the whole body, including the folds. Palmar plantar hyperkeratosis, the course of the disease is delayed, can survive in life, to adulthood erythroderma can be reduced, but scales still exist. One third of patients have severe ectropion and lip eversion.

5. circuitous linear ichthyosis

A general polycyclic ring-shaped rash on the trunk and near the extremities, with thickened and slowly changing keratinous margins on the periphery, and zygomatic moss formation or hyperkeratosis in the popliteal and elbow sockets. In some cases, flaccid subcorneal blisters may occur, and palmar plantar sweating. Most cases can be seen in bamboo shoots. Atopic dermatitis is often present at the same time. With age, the skin and hair gradually improve, but the skin is still dry and flakes are removed.

6. Congenital non bullous ichthyosis-like erythroderma

At birth, the baby is wrapped in a parchment-like or collodion-like film, with limited movement and ectropion. Cracking and exfoliation occurred within 24 hours, and after 10 to 14 days, a large keratinous plate peeled off and improved rapidly at the same time. With the exfoliation of the membrane, the erythema and scales below it are usually systemic and can involve the face, palmar plantar and flexor areas: the scales are larger, plate-like in the legs, and the trunk, face and scalp are smaller . Scarring alopecia, nail dystrophy, and ectropion are common and are often accompanied by pigmented retinitis. In addition, the disease may develop into skin cancer, including basal cell carcinoma and squamous cell carcinoma.

Ichthyosis diagnosis

1. have family history;

2. Skin lesions;

3. Histopathological changes

(1) Dominant hereditary ichthyosis with moderate hyperkeratosis of the epidermis with thinning or disappearance of the granular layer

(2) Sexual ichthyosis vulgaris, hyperkeratosis, normal or slightly thick granular layer;

(3) Epidermal hyperkeratosis and ichthyosis Epidermal hyperkeratosis or granular degeneration.

Ichthyosis treatment

Mainly symptomatic treatment, topical moisturizers keep the skin moisturized. Some patients can take vitamin A or retinoids orally. Topical glucocorticoid ointment or retinoid ointment.