Lamellar ichthyosis, also called ichthyosis lammellaris or nonbullous congenital ichthyosis, is a congenital skin condition characterized by hyperkeratosis, or thickening of the stratum corneum, the outermost layer of the skin. It results in a scaly appearance of the skin, particularly on the neck, groin, armpits, inner elbow, and similar joints. Lamellar ichthyosis is very rare, affecting only one in 600,000 people. It is a moderate form of ichthyosis, a group of genetic disorders that ranges from the very mild and relatively common ichthyosis vulgaris to the life-threatening harlequin-type ichthyosis.
Babies born with lamellar ichthyosis are referred to as "collodion babies" because they are born with a collodion membrane, which looks like an extra layer of skin, and is shed about two weeks after birth. The skin is shiny, waxy, and tight, and may pull the eyes and mouth wide open. Because of their abnormal skin, collodion babies are at risk of hypothermia, dehydration, skin infection, and intoxication from topically applied products. Nursing in a neonatal intensive care unit until the collodion membrane is shed, often including the use of topical moisturizers and a humidified incubator, helps address and prevent these risks. The condition is not painful or uncomfortable for the baby, though its complications may be.
Not all collodion babies have lamellar ichthyosis, and about ten percent experience no further symptoms after the collodion membrane is shed. About 15% have a different genetic skin disorder. Laboratory examination of the baby's skin, blood, or hair can help doctors make a diagnosis.
In addition to scaly, thickened skin, lamellar ichthyosis in children and adults can cause overheating due to defective sweating, dry and irritated eyelids, and temporary hair loss due to scaling on the scalp. Children with the condition sometimes develop tight bands around the fingers or toes that restrict circulation. There is no cure for lamellar ichthyosis, but it can be alleviated with moisturizers for the skin, and eye drops for dry eyes. In addition, patients should avoid hot weather and vigorous exercise to prevent overheating.