Epidermolytic hyperkeratosis (bullous ichthyosiform erythroderma)
This rare condition is inherited as an autosomal dominant disorder. Shortly after birth the baby’s skin becomes generally red and shows numerous blisters. The redness fades over a few months, and the tend-ency to blister also lessens, but during childhood a gross brownish warty hyperkeratosis appears, sometimes in a roughly linear form and usually worst in the flexures. The histology is distinctive: a thickened granular cell layer contains large granules, and clefts may be seen in the upper epidermis. The condition is caused by mutations in the genes (on chromosomes 12q13 and 17q21) controlling the production of keratins 1 and 10. A few patients with localized areas of hyperkeratosis with the same his-tological features have gonadal mosaicism, and so their children are at risk of developing the general-ized form of the disorder. Treatment is symptomatic and antibiotics may be needed if the blisters become infected. Acitretin has helped in severe cases.