A chronic, recurrent disease of the skin characterized by dry, well circumscribed, silvery, scaling papules and plaques of differing sizes.

The cause is unknown. However, due to the response of psoriasis to immunosuppressive drugs, it is suggested that an immunologic factor is involved. It is commonly seen in the family history.

The disease onset is gradual with the appearance of chronic remissions and recurrences. Trauma or injury may bring on an episode. Areas involved include: the scalp, behind the ears, and extensor surfaces of the extremities. There may be involvement of the nails, eyebrows, axillae, umbilicus, and anogenital region. The lesions are shiny, silvery scales that may be in papular or plaque form. The lesions heal without scar formation, and hair growth is not changed. The nails resemble a fungal infection. Some other problems associated with psoriasis include: psoriatic arthritis; erythrodermic psoriasis (the entire skin surface is red and covered with fine scales requiring possible hospitalization); and pustular psoriasis (sterile pustules are present, and typical lesions are absent).

Diagnosis is made by visual inspection since the lesions have specific characteristics. Tissue biopsy may aid in some cases.

Treatment cannot cure, but it can help control psoriasis. Careful use of ultraviolet light is helpful as well as skin lubricants, topical corticosteroids, topical vitamin D, and keratolytics. In severe skin or joint cases, antineoplastic drugs have been used. There are specified routines for using the creams and corticosteroids; with alternating rest periods to minimize relapses. Use of 10% salicylic acid in mineral oil, applied at night and washed out with a tar shampoo in the morning, is one recognized therapy for hard to treat scalp lesions.

Skin disorders lead to problems with an alteration in body image, and the need for ongoing counseling. Permanent remission of this condition is extremely rare.

• Rate systemic manifestations (e.g., psoriatic arthritis) separately. Psoriatic arthritis should be separately rated under Diagnostic Code 5009 (applying principles in Esteban v. Brown  6 Vet.App. 259 (1994).

• 38 CFR 4.118 (a) For the purposes of this section, systemic therapy is treatment that is administered through any route (orally, injection, suppository, intranasally) other than the skin, and topical therapy is treatment that is administered through the skin. 

• 38 CFR 4.118 (b) Two or more skin conditions may be combined in accordance with 38 CFR 4.25 only if separate areas of skin are involved. If two or more skin conditions involve the same area of skin, then only the highest evaluation shall be used.

• Rate complications such as psoriatic arthritis and other clinical manifestations (e.g., oral mucosa, nails) separately under the appropriate diagnostic code.