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INTRODUCTION

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

  • More than 20 ichthyoses exist; most are extremely rare and often part of multiorgan syndromes. The most common types are discussed here along with 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 as well as other infections.

    Classification
  • Ichthyosis vulgaris

  • X-linked ichthyosis

  • Lamellar ichthyosis

  • Epidermolytic hyperkeratosis

ICHTHYOSIS VULGARIS ICD-10: Q80.0

  • Characterized by excessively dry skin with fine white to gray to brown scales.

  • Affects extensors and torso.

  • Frequently associated with atopy, hyperlinear palms and soles, keratosis pilaris.

EPIDEMIOLOGY

AGE OF ONSET Three to 12 months.

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

INCIDENCE Common (1 in 250).

PATHOGENESIS

Filaggrin mutation. Epidermis proliferates normally but keratin is retained with a resultant thickened stratum corneum.

CLINICAL MANIFESTATION

Very commonly associated with atopy. When hyperkeratosis is severe, many patients have a cosmetic concern.

SKIN LESIONS 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 4-3). The face is usually spared but the 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. 4-4); in childhood, also on cheeks. The hands and feet are usually spared, but palmoplantar markings are more accentuated (hyperlinear).

FIGURE 4-1

Ichthyosis vulgaris: back Fine “fish scale”-like hyperkeratosis of the back.

FIGURE 4-2

Ichthyosis vulgaris: legs Symmetric fine scale with “fish scale” appearance.

FIGURE 4-3

Distribution of ichthyosis vulgaris Dots indicate keratosis pilaris. Palms with increased skin markings (hyperlinearity).

FIGURE 4-4

Ichthyosis vulgaris. Keratosis pilaris: arm Small, follicular, horny spines occur as a manifestation of mild ichthyosis vulgaris; arising mostly on the shoulders, upper arms, and thighs. Desquamation of the nonfollicular skin results in hypomelanotic (less pigmented) spots similar to pityriasis alba (compare with Fig. 13-18).

ASSOCIATED DISEASES More than 50% of individuals also have atopic dermatitis. ...

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