The various skin disorders that can result in erythroderma are the following: Different types of dermatitis (eg, atopic dermatitis, allergic contact dermatitis, seborrheic dermatitis) Psoriasis Pityriasis rubra pilaris Drug reactions Lichen planus Cutaneous T-cell lymphoma (particularly Sézary syndrome) Ichthyosis Erythroderma can develop in patients known to have skin disorders such as those above, but erythroderma can also develop spontaneously in patients without a history of prior skin problems.