Keratinization

Introduction The most important physiological function of the epidermis is to form a protective outer skin, the stratum corneum, to resist the various stimuli from the outside world. Epidermal cells will be transformed according to the order of basal cells acanthosis cells granulosa cells stratum corneum cells, and gradually move to the surface layer, and finally become keratinocytes. This process of differentiation of epidermal cells is called "keratinization." Epidermal hyperkeratosis can cause a series of skin diseases such as ichthyosis and palmoplantar keratosis, ecdysis and menopausal keratoderma.

Cause

The basal cells of the lowermost layer of the human epidermis successively become polygonal spine cells, flattened granulosa cells containing basophilic particles, flat cell-free nuclei and organelle keratinocytes. This process generally takes 28 to 45 days.

The differentiation process of the epidermis is controlled by many factors and is easily disturbed. Any factor that causes basal cell division and differentiation can cause hyperkeratosis and parakeratosis. Such as cyclic adenosine and cyclophosphoguanine, prostaglandins, polyamines, statins, adrenergic agonists and glucocorticosteroids, etc., all regulate the keratinization of the skin.

Excessive keratinization or keratinous accumulation can cause hyperkeratosis of the stratum corneum. The keratinization process is incomplete or abnormal in keratinization, resulting in parakeratosis and poor keratinization. There are many reasons for causing hyperkeratosis and abnormalities, which can be summarized as hereditary and acquired.

an examination

Related inspection

Skin smear microscopy skin test

A group of skin diseases characterized by hyperkeratosis of the epidermis. Can express local skin keratin hyperplasia, dry skin, scaly, chapped, generally no subjective discomfort, sometimes itching or pain, often worse in winter. It is generally easy to identify based on its clinical characteristics.

Commonly occurring in hereditary keratoderma are ichthyosis and palmoplantar keratosis. Both should be identified.

Differential diagnosis

Commonly occurring in hereditary keratoderma are ichthyosis and palmoplantar keratosis.

Ichthyosis:

Commonly known as ichthyosis. When the epidermis is increased or the adhesion is increased, scales may be generated, the scales are close to the surface and the edges are free, and the scales are arranged like fish scales, hence the name. According to its different genetic methods, it is divided into ichthyosis vulgaris, X-linked ichthyosis, lamellar ichthyosis and epidermolytic hyperkeratosis. It is the most common form of autosomal dominant ichthyosis, and it is estimated that one out of every 250 people may have this disease. The disease begins in young years and varies in severity. The lighter skin is only dry in winter, with a small amount of powdery scales and hairy moss. Some cases become lighter with age.

Scales are usually made with limbs. In cold and dry climates, the scaly and heel keratosis of the back and calves are more pronounced, and the palms and ankles can be split in a straight line. Sexual ichthyosis is a hereditary recessive hereditary, less common, only found in males, after onset or in infancy. Skin lesions are more common than ichthyosis, large and significant scaly, large yellow-stained or black-stained scaly scales can be spread throughout the body, the abdomen is particularly heavy than the back. Generally, follicular keratinization and palmar keratinization do not occur. With age, skin lesions are not alleviated, but worse. Lamellar ichthyosis is autosomal recessive. Skin lesions appear at birth or shortly after birth. They are characterized by large yellow-gray scales, which are square, with a central sticking, high edges, severe cases like armor, and a slightly flush base. Epidermal loosening hyperkeratosis is an autosomal dominant inheritance, formerly known as bullous ichthyosis-like erythroderma. At the beginning of the skin, it is red, moist, and painful. After a few days, thick scaly scales form. The scaly patches are polygonal and have deep red cracks around them, which ooze odorous bloody fluids. Hard keratin covers the entire body of the child, affecting breathing and swallowing, and most of them die within a few days after birth. The limited type has thicker squamous keratin slices only on the flexor and wrinkles of the extremities. This type is rare.

Palmoplantar keratosis:

A group of hereditary diseases characterized by marked keratinization of the palmar palpebral. Common ones are diffuse and disseminated, all of which are autosomal dominant. Diffuse palmoplantar keratosis is more common in childhood, manifested as obvious pale yellow keratosis, hard and smooth surface. In severe cases, it can proliferate like a scorpion, and there is a split in winter, involving the elbow, knee, ankle and sputum. Lighter can only affect the foot. Disseminated palmoplantar keratosis, also known as punctate palmoplantar keratosis, is characterized by a large round miliary to mung bean keratotic papules, hard and scattered in the palm of the hand. The more prominent ones in acquired keratosis are ecdysis and menopausal keratoderma.

Suede disease:

A skin manifestation of vitamin A deficiency. When vitamin A is deficient, it may be caused by its ability to inhibit polyamine synthesis, which causes this disorder characterized by hyperkeratosis. Occurs in children and young people, the performance of the upper extremity stretch side, the outer side of the thigh and the trunk, etc. There are many miliary large follicular papules, conical, dark red, hard, central spinous horny plug, remove the angle plug After leaving a small pit. Generally no symptoms. Because of the dense papules, the skin looks like a sable skin, hence the name.

Menopausal keratoderma:

Found in menopausal women, the performance of palm, ankle or palm and sputum at the same time hyperkeratosis, there is significant thickening. The disease can also be seen after ovarian or hysterectomy. Treatment with female hormones is ineffective. A group of skin diseases characterized by hyperkeratosis of the epidermis. Can express local skin keratin hyperplasia, dry skin, scaly, chapped, generally no subjective discomfort, sometimes itching or pain, often worse in winter. It is generally easy to identify based on its clinical characteristics.

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