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Ichthyoses: Introduction

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  • A group of hereditary disorders characterized by an excess accumulation of cutaneous scale, varying from very mild and asymptomatic to life threatening.

  • A relatively large number of types of hereditary ichthyoses exist; most are extremely rare and often part of multiorgan syndromes. The four most common and important types are discussed here plus a brief discussion of two syndromic ichthyoses and ichthyosis affecting the newborn.

  • Acquired ichthyosis can be a manifestation of systemic disease, malignancy, drugs, endocrine disease, autoimmune disease, and HIV and other infections.

  • Support groups such as Foundation for Ichthyosis and Related Skin Types (FIRST) exist.

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For an in-depth discussion of ichthyoses, see P Fleckman, JJ DiGiovanna, in L Goldsmith et al (eds): Fitzpatrick’s Dermatology in General Medicine, 8th ed. New York, McGraw-Hill, pp 507–538, 2012.

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Classification

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  • Dominant ichthyosis vulgaris (DIV)

  • X-linked ichthyosis (XLI)

  • Lamellar ichthyosis (LI)

  • Epidermolytic hyperkeratosis (EH)

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Dominant Ichthyosis Vulgaris (DIV)

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ICD-9: 701.1 ○ ICD-10: Q 80.0 Image not available.

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  • Characterized by usually mild generalized xerosis with scaling, most pronounced on lower legs; in severe cases large, tessellated scales.

  • Hyperlinear palms and soles.

  • Perifollicular hyperkeratosis (keratosis pilaris) usually on arms and legs.

  • Frequently associated with atopy.

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Epidemiology

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Age of Onset
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3 to 12 months.

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Sex
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Equal incidence in males and females. Autosomal dominant inheritance.

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Incidence
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Common (1 in 250).

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Pathogenesis

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Etiology unknown. There is reduced or absent filaggrin. Epidermis proliferates normally, but keratin is retained with a resultant thickened stratum corneum.

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Clinical Manifestation

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Very commonly associated with atopy. Cosmetic concern to many patients, particularly when hyperkeratosis is severe.

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Skin Lesions
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Xerosis (dry skin) with fine, powdery scaling but also larger, firmly adherent tacked-down scales in a fish-scale pattern (Figs. 4-1 and 4-2). Diffuse general involvement, accentuated on the shins, arms, and back, buttocks, and lateral thighs; axillae and the antecubital and popliteal fossae spared (Figs. 4-2 and 4-4); face usually spared but cheeks and forehead may be involved. Keratosis pilaris is perifollicular hyperkeratosis with little, spiny hyperkeratotic follicular papules of normal skin color either grouped or disseminated, mostly on the extensor surfaces of the extremities (Fig. 4-3); in childhood, also on cheeks. Hands and feet usually spared, but palmoplantar markings are more accentuated (hyperlinear).

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Figure 4-1.

Ichthyosis vulgaris: chest Fine fish scalelike hyperkeratosis of the pectoral area. This is a mild form of ichthyosis vulgaris.

Graphic Jump Location
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Figure 4-2.

Ichthyosis vulgaris: legs Grayish tessellated (tilelike), firmly bound down scales. The similarity to fish skin or the skin of an amphibian is ...

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