Large brown scale: DDx and Ix.  A case report of X linked ichthyosis and review of literature on treatment options 

Ichthyoses are a group of heterogeneous inherited and acquired disorders characterized by dry, thickened and scaly skin. We describe a 24-year old male with generalized scaling present since age seven. Examination demonstrated widespread course, thickened scaling affecting the upper and lower limbs, abdomen and torso with sparing of the palms, soles and face. Lamellar ichthyosis, ichthyosis vulgaris and x-linked ichthyosis were key differential diagnoses. Lamellar ichthyosis, which presents at birth as severe collodion baby, is primarily characterised by scaling of the whole body with no sparing of the flexor creases. This condition is often due to reduced levels of transglutaminase, which can be demonstrated by genetic testing. Ichthyosis vulgaris often presents as a mild scale between infancy and childhood with defining features of hyperlinear palms, atopy and keratosis pilaris. Definitive diagnosis is based upon histological absence of granular layer. Presenting between birth and infancy, x-linked ichthyosis is characterised by large, course, dark scales affecting most of the skin surface. In x-linked ichthyosis, definitive diagnosis is achieved with a steroid sulphate assay, demonstrating elevated serum levels of cholesterol sulphate, as was the case for our described patient. Ichthyosis management aims to address hydration, lubrication and keratolysis. Hydration and lubrication can be achieved with bathing, oils and humidification. Keratolytic agents are used to decrease keratinocyte adhesion, promoting stratum corneum desquamation, enhancing skin hydration. Systemic treatment is achieved with the use of retinoids, which reduce hyperkeratosis, lesion extent and increase barrier function.

Dr. Mitchell Robinson