๐ ็ธฝ็ฎ้ ๏ฝ ๐ ่ฑๆๅๆ๏ผๆฌ็ฏ๏ผ ๏ฝ ๐ ๅฎๆด็ฟป่ญฏ ๏ฝ โญ ็ฒพ่ฏ็ญ่จ
X-LINKED RECESSIVE ICHTHYOSIS
X-LINKED RECESSIVE ICHTHYOSISย ย ICD-10: Q80.1
โข Occurs in males, X-linked recessive; gene locus Xp22.32.
โข Steroid sulfatase deficiency. Accumulation of cholesterol sulfate resulting in retention hyperkeratosis associated with normal epidermal proliferation.
โข Incidence 1:2000 to 1:6000.
โข Onset soon after birth.
โข Prominent, adherent brown scales on the neck, extremities, trunk, and buttocks (Fig. 4-5).
โข Involvement of flexural regions (Fig. 4-6).
โข Absence of palm or sole involvement.
โข Comma-shaped stromal corneal opacities (asymptomatic) in 50% of adult males. Present in some female carriers.
โข Laboratory: Cholesterol sulfate level โ; increased mobility of ฮฒ-lipoproteins in electrophoresis. Steroid sulfatase decreased or absent.
โข Dermatopathology: Hyperkeratosis and granular layer present.
โข Prenatal diagnosis: Amniocentesis, steroid sulfatase โ in chorionic villus samples.
โข Course: No improvement with age. Worse in temperate climates and winter.
โข Management: Hydration of stratum corneum and keratolytic agents as in ichthyosis vulgaris. Marked improvement with systemic retinoids (acitretin and isotretinoin), intermittent treatment with careful monitoring of toxicity.
FIGURE 4-5 โข X-linked ichthyosis: trunk, buttocks, and armsโDark hyperkeratosis with tessellated scales gives a dirty appearance in this 12-year-old boy.
FIGURE 4-6 โข Distribution of X-linked ichthyosis.