Ichthyosis types

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. 

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 characteristics of hydration level and barrier function of SC in various types of dry skin were reviewed and summarized in Table 9.3. They are senile xerosis, seasonal allergic rhinitis, ichthyosis valgaris, and experimentally induced dry skin including atopic xerosis and dry skin by hemodialysis. The water content decreased in every type of dry skin and the free amino acids content also decreased corresponding to the decrease of the water content. However, the TEWL or the ceramide levels showed no clear tendency throughout every type of dry skin, especially ceramides showed higher or lower value even though the water content in SC was consistently lower in every type of dry skin. 

The efficacy of urea in the treatment of ichthyosis has been investigated in several clinical studies. Different types of evidence exist for the clinical efficacy and the data support at least evidence-level lb... 

Different types of evidence exist for the barrier-influencing properties of 4 to 10% urea in dry skin disorders (Table 19.7). The data support evidence at level lb for reduction of TEWL in ichthyosis and atopic dry skin and evidence at level II for dryness. 

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... 

All compounds that we have studied for effects on keratinization have been initially evaluated on a series of over twenty patients with ichthyosis of several types. Many of the compounds have been evaluated for therapeutic effects on larger series of patients with dry skin several have been used therapeutically for comedonous acne and a few have been used in therapy of a diverse group of disorders including palmar and plantar hyperkeratosis, Darier s disease, lichen simplex chronicus and others. Reduction in stratum corneum accumulation has been readily demonstrable in all disorders in response to two-four times daily topical application of the compounds formulated as 5-20% oil-in-water creams, as solutions and as gels. 

Table 6.3 Results of thymidine incorporation in patients with various types of ichthyosis...

Type of ichthyosis Number of patients or patient number from Table 2) Thymidine incorporation... 

It may be that the defect in the plasma membrane phospholipids presumably produced by the EFA deficiency is similar to an abnormality produced by the displacement of linoleic and arachidonic acids by the excess phytanic acid in Refsum s syndrome and that there is a special relationship between the plasma membrane and cell division. The normal rate of cell production in dominant ichthyosis that we have found is in agreement with previous workers and the scaliness in these patients is an optical and sensory effect from the abnormal type of desquamation in these patients rather than an increase in scale production. We believe that the hyperkeratotic type of lamellar ichthyosis is special in that there is a normal or low rate of cell production in contradistinction to the erythrodermatous types. 

Refsum s syndrome will only briefly be mentioned here, since our studies together with the dermatologic department of Professor Duperrat and Professor Puissant are reported by Dr. Blanchet-Bardon in more detail (Chapter 9). Though very similar to autosomal dominant ichthyosis vulgaris histopathologically, ichthyosis in Refsum s syndrome may be strictly differentiated from the dominant type by the consistently normal keratohyalin ultra-structure ... 

Ichthyosis linearis cirumflexa Cornel) will not be reported here. Frenk and Mevorah as well as Thorne and co-workers have shown that unknown substances are formed in the border of growing lesions where parakeratosis is present and keratohyalin granules are missing We found this process not only to be limited locally but to be restricted to short periods of abnormal differentiation (unpublished observations). In Netherton s syndrome, this type of ichthyosis is combined with trichorrhexis invaginata, the ultrastructure of which was described by Orfanos et aiy. ... 

Figure 10.7 Ichthyosis hystrix type Curth-Macklin. (a) Unbroken concentric shell of tonofilaments (TS) surrounding the nucleus (N) and perinuclear cytoplasm with ribosomes and granular endoplasmic reticulum (ER) x 16 000. (b) 3 binucleate cells ( ) in the prickle cell layer (compare with Figure 10.6a) x4000...

Finally, ichthyosis hystrix gravior has been reported repeatedly in the literature. It is worth remembering the famous cases of porcupine men of the Lambert family and the Bafverstedt type . A new case of ichthyosis hystrix gravior will briefly be reported. Areas of particularly severe involvement included the face, the ears, and the extremities. Skin malformation is combined in this patient with deafness of the inner ear. This patient has been demonstrated at the Dermatologic Joint Meeting at Heidelberg, October 1976 He seems to us to represent a special syndrome not only from the clinical point of view but also because of his unusual ultrastructural features. 

Intrinsic ultrastructural differences exist between the various types of inherited ichthyoses that may well be used as parameters for their classification. By electron microscopy a distinction is not only possible between representatives of the main clinical groups (ichthyosis vulgaris group, congenital ichthyoses, hystrix-like ichthyoses), but also between the different types within these groups. 

Structural abnormalities are demonstrable in some dominant types, in keratohyalin (defective in autosomal dominant ichthyosis vulgaris), and tono-filaments (impaired or disturbed in their arrangement in hystrix-like ichthyoses clump formation in bullous ichthyosiform erythroderma or epidermolytic hyperkeratosis shell formation associated with high numbers of binucleate cells in ichthyosis hystrix type Curth-Macklin impairment in ichthyosis hystrix gravior type Rheydt). Keratohyalin and tonofilaments are both structural proteins of keratinizing tissues. 

In most recessive types merely quantitative deviations from the normal keratinization process have been found (X-linked recessive ichthyosis, lamellar... 

Figure 10.8 Ichthyosis hystrix gravior with deafness (Type Rheydt). Blown-up cells of the granular layer with largely reduced amounts of tonofilaments (open arrow), normal or slightly rounded keratohyalin (KH) granules, and production of membrane-bound mucous granules (MG) that discharge their contents to the intercellular spaces ( ) A -nuclei x5500...

OUendorff-Curth, H., Allen, F. H., Schnyder, U. W. and Anton-Lamprecht, I. (1972). Follow-up of a family group suffering from ichthyosis hystrix type Curth-Macklin. Humangenetik, 17,37... 

Table 13.2 lists the major types of ichthyosis. In each category can be placed patients with unusual forms, with the reservation that a particularly unusual case may not truly be part of a sub-group of that disorder but, rather, either a distinct entity, or a sub-group of another major category. 

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