X-linked ichthyosis
Introduction
Introduction of X-linked ichthyosis X-linked ichthyosis (X-linkedichthyosis) is also known as ichthyosisnigricans, and X-linked recessive ichthyosis (recessiveX-linkedichthyosis). basic knowledge The proportion of illness: 0.005% Susceptible people: male Mode of infection: non-infectious Complications: testicular cancer cryptorchidism
Cause
X-linked ichthyosis
(1) Causes of the disease
In the 1860s, X-linked recessive ichthyosis was distinguished from other ichthyosis by clinical manifestations. Later studies found that the disease is associated with steroid sulfatase abnormalities, steroid sulfatase hydrolyzed sulfate, including cholesterol sulfate and Sulfated steroids, fetal epinephrine desulfurization, become estrogen, excreted from the mother's urine, the lack of steroid sulfatase in the fetal placenta can lead to a decrease in estrogen in the mother's urine, in some women, can also cause labor initiation and labor Obstacles, male sympathetic ichthyosis patients, reduced or lack of steroid sulfatase activity in many tissues, including epidermis, stratum corneum, white blood cells and cultured fibroblasts, in addition, the enzyme substrate - cholesterol sulfate can be in scales In the middle of accumulation, the level of white blood cell steroid sulfatase in female carriers is between normal individuals and male patients.
In men, the incidence of ichthyosis vulgaris is about 1:2000 ~ 1:6000, about half of adult male patients may have comma-like corneal opacity, but does not affect vision, but also in female carriers, male patients The incidence of cryptorchidism and testicular cancer increases, serum cholesterol, epidermis, and squamous cholesterol levels increase, and gel electrophoresis shows an increase in -lipoprotein (low-density lipoprotein), which can be used as one of the diagnostic features of serum sulfuric acid. When the cholesterol level is increased from normal 80-200 g/dl to 2000-9000 g/dl, the diagnosis can often be confirmed.
(two) pathogenesis
The steroid sulfatase gene is located on the short-armed two-zone, two-band, and three-subbands of the X chromosome (Xp22.3). About 80% of patients have this enzyme gene deficiency. For example, sclerotin dysplasia and X-linked ichthyosis can occur in the absence of sulfatase deficiency. Overlap syndrome.
In the epidermis, steroid sulfatase catalyzes the hydrolysis of cholesterol sulfate. The deficiency of steroid sulfatase in X-linked ichthyosis patients indicates that the hydrolysis of sulphuric acid cholesterol is very important for normal desquamation. In mice, topical sulphuric acid cholesterol can induce desquamation abnormalities. Further support for the hydrolysis of cholesterol sulfate plays a role in the dissociation of keratinocytes.
However, some studies have found that some patients have normal steroid sulfatase activity and no corneal opacity, which shows the genetic heterogeneity of X-linked ichthyosis, so male ichthyosis patients with normal steroid sulfatase levels cannot exclude X- Linkage recessive hereditary ichthyosis.
Prevention
X interlocking ichthyosis prevention
Avoid close relatives to get married, prevent excessive dryness of the skin, and disable alkaline heavy soaps and irritating drugs.
Complication
X interlocking ichthyosis complications Complications testicular cancer cryptorchidism
Male patients may have cryptorchidism and testicular cancer.
Symptom
X-linked ichthyosis symptoms common symptoms squamous pigmented lesions
Almost all of them are seen in males. They occur at birth or shortly after birth. The limbs, face, neck, trunk, and buttocks often have large and significant scales. The neck, face, and trunk are the most affected. Individual cases or severe cases can affect the elbow. Under the armpits and armpits, the palmar appearance is normal or slightly thickened. The scales are often brown and sticky. Female carriers have mild scales in front of the arms and ankles. Eye slits are examined. Some patients can see the posterior corneal wall. Or the elastic layer is turbid, male patients may have cryptorchidism and testicular cancer, and the skin lesions do not decrease with age.
Examine
X interlocking ichthyosis examination
Histopathology: excessive keratinization, normal or slightly thickened granular layer, decreased sweat glands, and lymphatic-based perivascular inflammatory cell infiltration in the dermis.
Diagnosis
Diagnosis and identification of X-linked ichthyosis
According to the clinical manifestations, the characteristics of skin lesions and histopathological features can be diagnosed.
Differential diagnosis
1. Acanthosis nigricans is more common in adults, more invading the armpits, groin and vulva and other skin wrinkles and deep spots of physiological pigments. The skin lesions are brown patches, and the histopathological findings show papillary-like proliferation, often complicated by visceral cancer.
2. Congenital ichthyosis-like erythroderma appears ichthyosis-like damage on the basis of diffuse flushing of the skin, with the body flexing side and increasing in summer.
3. The scaly hair follicles have black spots in the center of the keratinized scaly, which are consistent with the hair follicles. The central fixation is visible, and the surrounding small leaf-like scales are more common in the waist, buttocks and ventral side.
