Laboratory Studies
No general laboratory studies are needed for epidermolytic ichthyosis (EI), except if necessary to follow chosen therapy or bacterial culture for suspected infection.
Genetic studies can be performed on buccal swabs or blood. Once a mutation is identified in an affected individual, mutation-specific testing for relatives and prenatal diagnosis is available.
Procedures
Along with clinical presentation and history, skin biopsy can be helpful, with the histologic findings confirming a diagnosis of epidermolytic ichthyosis.
Prenatal diagnosis can be made through chorionic villus sampling, analysis of amniotic cells, or fetal skin biopsies.
Histologic Findings
In epidermolytic ichthyosis, hematoxylin and eosin findings are distinctive but not unique to epidermolytic ichthyosis. Typical findings include marked hyperkeratosis, a thick granular layer, coarse keratohyaline granules, and vacuolar degeneration of the upper epidermis. Occasionally, deeper granular cells become dense, enlarged, and irregular, and the shaped masses appear to be keratohyaline granules. In addition, dyskeratosis is frequently present to varying degrees. [18] Patients whose pathologic slides demonstrate continuous involvement of the entire horizontal epidermis with these distinctive findings are more likely to have generalized disease; those with focal involvement revealing skip areas of normal epidermis are more likely to have a mosaic form of epidermolytic ichthyosis. [19]
On electron microscopy, large, round-to-oval, dense clumps of keratin tonofilaments can be seen in the lower epidermal layers.
Hematoxylin and eosin staining of epidermolytic ichthyosis is shown in the images below.
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Pathology of epidermolytic ichthyosis (hematoxylin and eosin stain).
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Pathology of epidermolytic ichthyosis (hematoxylin and eosin stain).
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The scale in epidermolytic ichthyosis is classically described as "corrugated". Patients often experience erosions as a result of skin fragility.
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The scale in epidermolytic ichthyosis is classically described as "corrugated". Patients often experience erosions as a result of skin fragility.
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Palms and soles may have varying degrees of hyperkeratosis.
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Hyperkeratosis involving the abdomen.
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Hyperkeratosis involving the knee.
