Common ichthyosis

In both types of common ichthyosis, scaling is usually most apparent on the extensor surface of the extremities, but it may also appear on the trunk, especially in XRI (Figure 8.2). Xerosis of the skin is a prominent feature in most patients, but there is no skin inflammation unless ichthyosis is complicated by, for example, atopic eczema (common in IV) or microbial infections. 

Ichthyosis vulgaris is the most common ichthyosis and its onset during childhood is distinctive. The condition is transmitted as an autosomal dominant trait. The trunk and extensor surfaces of the limbs are the site of fine, white and branny scales which may have a pasted on appearance. The flexures are characteristically spared. The face scales only during early childhood. Palms and soles have prominent markings. 

Recessive X-linked ichthyosis (RXLI) is a dermatological condition that is caused by steroid sulfatase deficiency (STSD), although the mechanism by which the deficiency causes the characteristic scaly skin has not been adequately explained. RXLI is the most common genetic disorder of steroid metabolism, affecting about 1 2000 males. Epstein and workers [16] first demonstrated that serum cholesterol sulfate was elevated in the condition, and this compound has become the preferred analyte for diagnosis. The serum level is more than tenfold greater than normal in the condition. 

The most common forms of ichthyosis — autosomal dominant ichthyosis vulgaris (IV) and X-linked recessive ichthyosis (XRI) — in many countries occur at frequencies a high as 1/300 and 1/2500, respectively. In fact, the genetic traits for IV and XRI are so frequent that the two diseases sometimes coexist in one and the same family, which may cause confusion as to the inheritance pattern. Although the incidence of IV and XRI is probably similar around the world, climate differences in particular will affect the severity of the disease, and hence its notification by the health care system. 

The two most severe types of ichthyosis, lamellar ichthyosis (LI) and epidermolytic hyperkeratosis (EHK), are distinct families of diseases with completely different etiologies (see Figure 8.1 and Table 8.3). Nevertheless, LI and EHK have several things in common they are rare, congenital diseases (prevalence <1/100,000) with more or less generalized hyperkeratosis and a defective skin barrier, and they usually demands vigorous therapy. 

The S ACD can be employed to sample and quantify loose corneocytes and squames from the skin surface. Such a procedure is only valid for conditions where the intercorneocyte bonds are weaker than the SACD adhesion to the SC.14 In fact, tiny scales found in the common type of facial dry skin, dandruff, and seborrheic dermatitis come off quite easily.31-42 By contrast, thick compact adherent scales found in ichthyosis and severe winter xerosis of the lower legs12 31 are not reliably harvested using SACD. This represents a classical pitfall of the method.14... 

Any disruption in the biosynthetic pathway will lead to very low maternal serum UE3. Conditions that cause disruption include fetal anencephaly, placental sulfatase deficiency, fetal death, chromosome abnormalities, molar pregnancy, and Smith-Lemlit Opitz syndrome (SLOS). Placental sulfatase deficiency presents in the infant as X-linked ichthyosis. It is present in approximately 1 in every 2000 males. Because of the lack of uEj, the mother often has delayed onset of labor. The cesarean section rate is significantly higher in these mothers. SLOS is a serious, rare birth defect that is the result of an inborn error in cholesterol metabolism, 7-dehydrosterol-7-reductase deficiency. Down syndrome leads to a modest decrease in uEj. Screening for Down syndrome is now the most common application of uEs measurements. ... 

Keratolytics are available in a multitude of formulations for treating skin diseases. Prolonged use of salicylic acid preparations over large areas, especially in children and patients with renal and hepatic impairment, can result in salicylism. Irritation is a common side effect with higher concentrations. Lactic acid (Lac-hydrin, others) is an emoUient that contains 12% lactic acid, which is an effective moisturizer indicated for the treatment of xerosis and ichthyosis vulgaris. 

Localized systematized form — The systematized form with extensive symmetrical lesions, commonly designated as ichthyosis hystrix is frequently associated with skeletal deformities and central nervous defects such as mental retardation, epilepsy and neural deafness. ... 

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