Superficial Epidermolytic Ichthyosis

Superficial epidermolytic ichthyosis (SEI) is a rare keratinopathic ichthyosis (KI; see this term) characterized by the presence of superficial blisters and erosions at birth.

Epidemiology

Less than 30 families have been reported in the literature.

Clinical description

Clinical features of SEI are similar but milder that those of epidermolytic ichthyosis (EI; see this term). SEI presents at birth or during the neonatal period with mild superficial blistering that is more frequent on flexures, shins, abdomen and extremities. After a few weeks, the skin starts to peel leaving characteristic denuded areas with normal skin (called molting/ mauserung phenomenon). A variable and mild grey rippled hyperkeratosis develops predominantly on the limbs, lower trunk and flexural areas. Blistering diminishes with age but persists through childhood and sometimes into adult life in response to trauma, heat or excessive sweating. Palmoplantar involvement is usually not observed but palmoplantar blistering, usually associated with hyperhidrosis, may sometimes occur. Skin odor is not present.

Etiology

SEI is caused by mutations in the KRT2 gene encoding keratin 2. These mutations impair keratin filament formation and weaken the structural stability of the keratinocyte cytoskeleton.

Diagnostic methods

Diagnosis is based on clinical and histological examination of skin lesions biopsies revealing acanthosis, a prominent granular layer, epidermolytic changes in the granular and upper spinous layers, hyperorthokeratosis and intracorneal blister formation. On electron microscopic examination, keratinocytes of the granular layer display structural alterations of tonofilaments. Molecular analysis, if available, reveals KRT2 mutations.

Differential diagnosis

Differential diagnosis includes epidermolytic ichthyosis, peeling skin syndrome, staphylococcal scalded skin syndrome, Alopecia-contractures-dwarfism-intellectual disability syndrome (see these terms), and atopic dermatitis.

Antenatal diagnosis

Genetic prenatal diagnosis is available for inherited ichthyoses (see this term) but it is generally not proposed for SEI due to its mild course.

Genetic counseling

Transmission is autosomal dominant. Genetic counseling should be offered to affected families. The risk for an affected parent to have an affected child is 50%.

Management and treatment

Treatment is symptomatic. Emollient and mild topical keratolytics may be used to reduce hyperkeratosis. Low dose of oral retinoids may also reduce hyperkeratosis, but must be used with caution because of their side effects and of their effect in the increase of skin fragility. Antibiotic therapy is required to treat secondary infection.

Prognosis

SEI is usually a mild disease. Life expectancy is normal and quality of life is not severely impaired.