Diagnosis: Ichthyosis
Photo of "mosaic lines" on my left leg, between achilles and calf muscles. I've had these on both of my legs for decades, but just learned today that they are "tell-tale" signs of Ichthyosis vulgaris. Clinical photograph sourced from Wikimedia Commons (CC BY-SA 3.0). Attribution: Skoch3.
Ichthyosis vulgaris: fine white-gray scale on extensor surfaces, sparing flexures. Keratosis pilaris and hyperlinear palms common. X-linked ichthyosis: larger, darker scales, may involve flexures. Lamellar/CIE: collodion baby at birth, generalized erythema and scale.
Onset in infancy or early childhood. Family history (AD for vulgaris, X-linked recessive for XLI). Worsens in winter/dry conditions. IVig associated with atopic dermatitis in 50%. Acquired ichthyosis in adults: consider underlying malignancy (lymphoma), medications.
Emollients (cornerstone — apply to damp skin). Keratolytics: ammonium lactate 12%, urea 10-40%, salicylic acid. Topical retinoids for severe cases. Systemic retinoids (acitretin) for severe congenital ichthyoses. Avoid hot water, harsh soaps.
Atopic dermatitis, Psoriasis, Tinea, Lamellar ichthyosis, Netherton syndrome, Acquired ichthyosis
Filaggrin mutations link ichthyosis vulgaris and atopic dermatitis pathogenetically. Collodion baby is a medical emergency requiring NICU care. Acquired ichthyosis in an adult should prompt investigation for underlying malignancy, particularly lymphoma.
Tags: ichthyosis, keratinization, genetic, xerosis, scaling