Introduction
Background
Lamellar ichthyosis (LI) is an autosomal recessive disorder that is apparent at birth and is present throughout life. The newborn is born encased in a collodion membrane that sheds within 10-14 days. The shedding of the membrane reveals generalized scaling with variable redness of the skin. The scaling may be fine or platelike, resembling fish skin. Although the disorder is not life threatening, it is quite disfiguring and causes considerable psychological stress to affected patients.
Collodion baby with translucent membrane of the body.
Pathophysiology
Patients with lamellar ichthyosis have accelerated epidermal turnover with proliferative hyperkeratosis, in contrast to retention hyperkeratosis. This involves a mutation in the gene for transglutaminase 1 (TGM1). The transglutaminase 1 enzyme is involved in the formation of the cornified cell envelope. The formation of the cornified cell envelope is an essential scaffold upon which normal intercellular lipid layer formation in the stratum corneum occurs. Thus, mutations in the TGM1 secondarily cause defects in the intercellular lipid layers in the stratum corneum, leading to defective barrier function of the stratum corneum and to the ichthyotic phenotype seen in lamellar ichthyosis patients and in transglutaminase 1 knockout mice. How much a defective cornified cell envelope alone contributes to the barrier abnormality in ichthyoses remains unclear.1
To date, 6 genes for lamellar ichthyosis have been localized and 5 of them identified, as follows2 :
- TGM1 (14q11)
- ABCA12 (2q34)
- 19p12-q12
- 19p13
- ALOXE3-ALOX12B (17p13)
- ichthyin (5q33)
Frequency
United States
Prevalence is less than 1 case per 300,000 individuals.
Mortality/Morbidity
- In the neonatal period, following the shedding of the collodion membrane, the newborn is at risk for secondary sepsis and hypernatremic dehydration.
- As the child ages, the hyperkeratosis can interfere with normal sweat gland function, which can predispose to heat intolerance and possible heat shock. Ectropion may result in the inability to fully close the eyelids and can cause exposure keratitis.
Race
- Lamellar ichthyosis affects all populations.
Sex
- Incidence in males and females is equal.
Age
- The disease is present at birth and continues throughout life.
- A rare phenotype of lamellar ichthyosis has been described in South Africa. The term bathing-suit ichthyosis describes the characteristic distribution of the lesions, which involve the trunk, the proximal parts of the upper limbs, the scalp, and the neck, with sparing of the central face and extremities. This form of lamellar ichthyosis is caused by a homozygous missense mutation in TGM1.3,4
Clinical
Physical
Newborn period
The newborn presents encased in a tough, filmlike membrane that fissures when stretched. This collodion membrane is shed by 10-14 days, revealing generalized erythema and scaling.
Childhood and adulthood
- Skin: The disease is characterized by generalized scales, which range from fine and white to thick, dark, and platelike. The scales are arranged in a mosaic pattern resembling fish skin. The lesions involve the entire body and are increased in flexural surfaces such as the axilla, groin, antecubital fossa, and neck. The individual scales tend to be larger over the legs and, in some areas, are centrally attached and raised at the edges.
Keratoderma of the palms in a patient with lamellar ichthyosis. Courtesy of Dirk Elston, MD.
- Nail abnormalities: These include secondary dystrophy with nail fold inflammation, subungual hyperkeratosis, and longitudinal or transverse stippling. The nails may grow 2-3 times the normal rate.
Nail dystrophy and inflammation of the nail folds. Courtesy of M. Bryan, MD.
- Scalp: Scarring alopecia can result from the overall tightness of skin and the thick stratum corneum entrapping hairs. The hair may be thin and fine but, similar to the nails, can grow at 2-3 times the normal rate.
- Other findings: The lips and mucous membranes tend to be spared. Other associated features are ectropion, eclabium, bilateral conjunctivitis, small and deformed ears, and inflexible digits due to taut skin.
Inflexible fingers due to taut skin in a young patient with lamellar ichthyosis. Courtesy of Dirk Elston, MD.
Causes
Lamellar ichthyosis is an autosomal recessive disorder in almost all cases. Genetic linkage studies have been performed on families with classic lamellar ichthyosis and show markers on band 14q11 in the region of the TGM1 gene locus. An autosomal dominant form of lamellar ichthyosis has been described.5
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References
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Oji V, Traupe H. Ichthyoses: differential diagnosis and molecular genetics. Eur J Dermatol. Jul-Aug 2006;16(4):349-59. [Medline].
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Kragballe K, Steijlen PM, Ibsen HH, et al. Efficacy, tolerability, and safety of calcipotriol ointment in disorders of keratinization. Results of a randomized, double-blind, vehicle-controlled, right/left comparative study. Arch Dermatol. May 1995;131(5):556-60. [Medline].
Abdel-Magid EH, el-Awad Ahmed FR. Salicylate intoxication in an infant with ichthyosis transmitted through skin ointment--a case report. Pediatrics. Dec 1994;94(6 Pt 1):939-40. [Medline].
Ramirez ME, Youseef WF, Romero RG, et al. Acute percutaneous lactic acid poisoning in a child. Pediatr Dermatol. May-Jun 2006;23(3):282-5. [Medline].
Allen DM, Esterly NB. Significant systemic absorption of tacrolimus after topical application in a patient with lamellar ichthyosis. Arch Dermatol. Sep 2002;138(9):1259-60. [Medline].
DiGiovanna JJ. Ichthyosiform Dermatoses. In: Freedberg IM, Eisen AZ, Wolff K, Austen KF, Goldsmith LA, Katz SI, Fitzpatrick TB, eds. Fitzpatrick's Dermatology in General Medicine. Vol 1. 5th ed. New York, NY: McGraw-Hill; 1999:587-8.
Novice FM, Collison DW, Burgdorf WHC, Esterly N, eds. Lamellar ichthyosis. In: Handbook of Genetic Skin Disorders. Philadelphia, Pa: WB Saunders; 1994:9-12.
Spitz JL. Lamellar ichthyosis. In: Spitz JL, ed. Genodermatoses. Baltimore, Md: Williams & Wilkins; 1996:8-9.
Sybert VP. Lamellar Ichthyosis. In: Sybert VP, ed. Genetic Skin Disorders. ed. New York, NY: Oxford University Press; 1997:27-30.
Further Reading
Keywords
lamellar ichthyosis, ichthyosis, congenital ichthyosis, nonbullous congenital ichthyosiform erythroderma, non-bullous congenital ichthyosiform erythroderma, autosomal recessive ichthyosis, erythrodermic autosomal recessive lamellar ichthyosis, EARI, nonerythrodermic autosomal recessive lamellar ichthyosis, NEARLI, non-erythrodermic autosomal recessive lamellar ichthyosis
