Erythroderma:

Generalized involvement of the skin with systemic manifestations (such as fever, weight loss, or hypoproteinemia) AND one of the following

Constant or near-constant systemic therapy such as therapeutic doses of corticosteroids, other immunosuppressive drugs, retinoids, PUVA (psoralen with long-wave ultraviolet-A light), UVB (ultraviolet-B light) treatments, biologics, or electron beam therapy required over the past 12 month period; or No current treatment due to a documented history of treatment failure with 2 or more treatment regimens

Generalized involvement of the skin without systemic manifestations and one of the following

Constant or near-constant systemic therapy such as therapeutic doses of  corticosteroids, other immunosuppressive drugs, retinoids, PUVA, UVB treatments, biologics, or electron beam therapy required over the past 12-month period; or No current treatment due to a documented history of treatment failure with 1 or more treatment regimens

Any extent of involvement of the skin, and any of the following therapies required for a total duration of 6 weeks or more, but not constantly, over  the past 12- month period: systemic therapy such as therapeutic doses of corticosteroids, other immunosuppressive drugs, retinoids PUVA, UVB treatments, biologics, or electron beam therapy

Any extent of involvement of the skin, and any of the following therapies required for a total duration of less than 6 weeks over the past 12-month period: systemic therapy such as therapeutic doses of corticosteroids, other immunosuppressive drugs, retinoids, PUVA, UVB treatments, biologics, or electron beam therapy

Any extent of involvement of the skin, and; no more than topical therapy required during the past 12-month period