Exfoliative dermatitis, or erythroderma, is an erythematous, scaly dermatitis involving most, if not all, of the skin. This generalized scaling eruption of the skin is drug induced, idiopathic, or secondary to underlying cutaneous or systemic disease. Appreciation for this condition requires an understanding of the skin’s normal epithelial layer. Normal epidermis has a continual turnover of epithelial cells. Cell division occurs near the basal layer. As cells move toward the periphery, they become well keratinized. This process requires approximately 10-12 days. Cells subsequently remain in the stratum corneum for another 12-14 days prior to being sloughed off.

In exfoliative dermatitis, the mitotic rate in the basal layer increases and overall transit time decreases; therefore, more cells are lost from the surface. The mechanism responsible for this is not known, although an immunologic basis has been suggested.