Hydrocortisone ointment 1% twice daily will settle irritation and scaling but will not restore pigmentation. This requires graduated sun exposure to the pale areas while using a sunscreen daily to avoid excess tanning of the skin that is not affected. As this is quite difficult to do, it is often better to ignore the condition, which improves with age.
Ichthyosis is a genetically determined skin condition. It presents at or soon after birth and persists throughout life. Affected patients have chronically dry, scaly skin.
Ichthyosis is often confused with atopic dermatitis, but it lacks the itch and inflammatory component (unless there is concomitant atopic dermatitis). There are many forms, dominantly inherited ichthyosis vulgaris, X-linked and a number of recessively inherited forms. Most are quite rare; ichthyosis vulgaris is the most common. In patients with ichthyosis vulgaris, the skin surface is dry and scaly. This may be obvious only on the lower legs. Additionally, these children have ‘hyperlinear’ palms and soles; in other words, the normal lines seen on these surfaces are accentuated. In the more severe X-linked ichthyosis, seen only in boys, the lower legs may exhibit a ‘crazy- paving’ appearance (Figure 7) and the whole skin may be dry, particularly early in life. All forms of ichthyosis are more troublesome in dry, cool weather. The recessive ichthyosis skin dryness is of a degree that will not be confused with eczema and patients’ very abnormal skin is usually obvious from birth, when most present as ‘collodion babies’ with an appearance of being encased in plastic wrap as neonates.
Treatment of ichthyosis consists of avoidance of products that dry the skin, such as soap, shampoo and bubble bath. A dispersible bath oil and moisturiser need to be used daily and can make the skin appear relatively normal. Generally, greasier preparations are more useful, particularly in winter. Excess scale may be removed with a preparation containing a keratolytic such as urea 10%, salicylic acid 2 to 6%, lactic acid 10% or propylene glycol 10 to 20%. Urea cream containing sodium pyrrolidone carboxylate is particularly useful. However, keratolytics may cause stinging and may be poorly tolerated by children. Topical corticosteroids are not required in the treatment of ichthyosis unless there is also atopic dermatitis.
Present in about 50% of the population, keratosis pilaris is a very common, dominantly inherited condition. It comprises very small keratotic papules found predominantly on the upper outer arms and lateral thighs (Figure 8). It is often also found on the cheeks in young children. Rarely, it generalises and is then termed follicular ichthyosis. Sometimes the lesions appear pustular but are usually sterile.
Keratosis pilaris is asymptomatic. Some parents see it as a cosmetic problem and a few are truly distressed by it. Occasionally, it may appear erythematous, which can be a cosmetic problem, particularly if it is on the face. Sometimes it is confused with dermatitis and inappropriately treated with corticosteroids.
The prognosis of this condition is good. The facial papules disappear around puberty, and although the lesions elsewhere may be most prominent in the second decade, they become less obvious with advancing age.