ICD-9: 701.1 ○ ICD-10: Q 80.0
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.
Equal incidence in males and females. Autosomal dominant inheritance.
Etiology unknown. There is reduced or absent filaggrin. Epidermis proliferates normally, but keratin is retained with a resultant thickened stratum corneum.
Very commonly associated with atopy. Cosmetic concern to many patients, particularly when hyperkeratosis is severe.
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).
Ichthyosis vulgaris: chest Fine fish scalelike hyperkeratosis of the pectoral area. This is a mild form of ichthyosis vulgaris.
Ichthyosis vulgaris: legs Grayish tessellated (tilelike), firmly bound down scales. The similarity to fish skin or the skin of an amphibian is quite obvious. Note sparing of popliteal fossae. This is a more severe form of ichthyosis vulgaris.
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. 3-18).
Distribution of ichthyosis vulgaris Dots indicate keratosis pilaris.
More than 50% of individuals with DIV also have atopic dermatitis, rarely keratopathy.
Xerosis; acquired ichthyoses, all other forms of ichthyosis.
Compact hyperkeratosis; reduced or absent granular layer; small, poorly formed keratohyalin granules by electron microscopy, germinative layer flattened.
By clinical findings; abnormal keratohyalin granules in electron microscopy.
Improvement in the summer, in humid climates, and in adulthood. Keratosis pilaris occurring on the cheeks during childhood usually improves during adulthood.
Hydration of Stratum Corneum
Best accomplished by immersion in a bath followed by the application of petrolatum. Urea-containing creams bind water in the stratum corneum.
Propylene glycol–glycerin–lactic acid mixtures. Propylene glycol (44–60% in water); 6% salicylic acid in propylene glycol and alcohol, used under plastic occlusion (beware of hypersalicism). α-Hydroxy acids (lactic acid or glycolic acid) control scaling. Urea-containing creams and lotions (2–10%) are effective.
Isotretinoin and acitretin are very effective, but careful monitoring for toxicity is required. Only severe cases may require intermittent therapy.