Ichthyoses/Disorders of Cornification
Wednesday, October 15, 2008
Ichthyosis results from abnormal retention and/or production of
the stratum corneum layer of the epidermis. Acquired ichthyosis can
be a cutaneous manifestation of an underlying disease (eg,
malignant neoplasm, metabolic disorder, malabsorption). The genetic
ichthyoses comprise a heterogeneous group of disorders that are
either limited to the skin (primary ichthyoses) or part of a
systemic or developmental disease complex (eg, Sjögren-Larsson
syndrome, Refsum disease). Not only are these disorders diverse in
etiology, but the extent of scaling is variable as well, ranging
from mild to severe. Regardless of the diagnosis, the therapeutic
strategy is similar and related to the extent and severity of the
process rather than to the specific diagnosis. Thus, for practical
purposes, management is separated here into the therapy of mild and
H2 First Steps
Emollients with added alpha-hydroxy acids (lactic acid), or
hygroscopic agents (urea) are usually tried first. The efficacy of
these agents are similar and the clinician may choose ammonium
lactate 12% gel, lactic acid 6% lotion, or 40% urea in petrolatum
with or without 5-10% lactic acid depending on the degree of
emollience needed. Each of these preparations is applied daily
immediately after bathing, while skin is still damp.
- Occlusive therapy: Hydrated petrolatum with 6% lactic acid; or
with 10-20% urea; or 40% propylene glycol in water-(any of the
above), applied overnight under a space suit or occlusive treatment
Most milder forms of ichthyosis are accompanied by a relative
inability of the skin to retain moisture. Therefore, the following
general measures should be used in all cases regardless of
- Oilated baths one half cup/bath daily: Soak at least 15 minutes
in the tub to hydrate the skin. Apply the appropriate topical agent
(above) immediately after bathing on still-moist skin.
- Cool-water bathing, in general, will result in less
delipidization, and hence, better water retention of the stratum
- Milder soaps: Glycerinated or nonglycerinated, and oilated
soaps are equally effective. Soap should be applied to the axillae,
groin, and scalp only.
- The inherited ichthyoses are life-long diseases, and therapy
should be adjusted for maximum patient convenience.
- The hydroxy acids (ie, lactic acid lotion, ammonium lactate
gel, or glycolic acid lotion) are especially efficacious in
X-linked ichthyosis, and may be the only specific therapy needed
for this disease.
- Patients with acquired ichthyosis need to be evaluated for
associated systemic diseases.
- Exacerbations in winter and remissions in summer are the rule
for the milder forms of ichthyosis, and therapy should be adjusted
Severe forms of ichthyosis generally require the same topical
approaches as milder forms. However, in addition, systemic
retinoids may be indicated. Because the doses required for
successful control of bullous ichthyosiform erythroderma
(epidermolytic hyperkeratosis), lamellar ichthyosis, and nonbullous
congenital ichthyosiform erythroderma generally are higher than
those used for other applications (eg, acne, cancer
chemoprevention, or psoriasis), acute side effects can be more
severe. Moreover, the benefits of improvement of the skin must be
weighed against long-term risks of systemic retinoid therapy.
Finally, in prepubertal children, there is the additional risk of
premature closure of the epiphyses.
- Acitretin 1-2 mg/kg/day.
- Isotretinoin 2-4 mg/kg/ day; initial therapy should be at the
lower dose levels indicated.
- Improvement should be evident within 6 weeks. If no change has
occurred, the dose can be increased. If and when dramatic
improvement has occurred, attempts should be made to reduce the
dosage, and/or to use every-other-day therapy.
- Topical therapy should be pursued aggressively throughout to
allow reduction in total dosage of systemic retinoids.
- As the structural abnormality of the skin is different for
different disorders, the percutaneous absorption may be diminished,
normal, or enhanced. Topical products that are potentially
irritating or absorbed may result in cutaneous or systemic
toxicities. Topical salicylic acid may cause salicylism or
persistent hypoglycemia if enhanced percutaneous absorption occurs
and excretion is reduced. This is particularly likely to occur in
neonates or adults with impaired renal function.
- Many persons with ichthyosis vulgaris also have atopic
dermatitis. High concentrations of lactic acid (>5%) may
exacerbate or trigger an inflammatory dermatosis in atopics. Lower
concentrations of lactic acid in combination with urea is preferred
- Patients on long-term systemic retinoid therapy require
monitoring of serum lipids, liver function tests, and complete
blood count with platelets, as well as sequential radiographic
studies (to look for calcification of the ligaments and premature
epiphysial closure). Retinoid therapy is best managed by a
physician with special expertise in these applications at these