AUTHOR AND EDITOR INFORMATION

Section 1 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

INTRODUCTION

Section 2 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Background

Psoriasis is a noncontagious skin disorder that most commonly appears as inflamed, edematous skin lesions covered with a silvery white scale. The most common type of psoriasis is plaque psoriasis.

Flares may be related to systemic or environmental factors, including life stress events and infections.

Discoid/plaque psoriasis is the most common type and is characterized by patches on the scalp, trunk, and limbs. The nails may be pitted and/or thickened.

Psoriasis may occur on the oral mucosa as well, although it is rare.

Pathophysiology

The skin is the primary organ affected, but joints also are affected in 10% of cases.

Frequency

United States

Between 2 and 2.6% of the US population is affected. Between 150,000 and 260,000 new cases of psoriasis occur annually.

International

Incidence of psoriasis is dependent on the climate and genetic heritage of the population. It is less common in the tropics and in dark-skinned persons.

Mortality/Morbidity

• Four hundred people die annually from psoriasis-related causes in the US.
• Approximately 1.5 million people with psoriatic arthritis seek medical care each year in the US.

Race

Psoriasis is more common in whites.

Sex

Psoriasis is slightly more common in women.

Age

Approximately 10-15% of new cases begin in children younger than 10 years. The median age at onset is 28 years.

CLINICAL

Section 3 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

History

• Worsening of a long-term erythematous scaly area
• Sudden onset of many small areas of scaly redness
• Recent streptococcal throat infection, viral infection, immunization, use of antimalarial drug, or trauma
• Family history of similar rash
• Pain
• Pruritus
• No fever
• Vesicles
• Long-term rash with recent presentation of joint pain

Physical

Findings on physical examination depend on the type of psoriasis.

• Plaque psoriasis is characterized by raised inflamed lesions covered with a silvery white scale. The scale may be scraped away to reveal inflamed skin beneath. This is most common on the extensor surfaces of the knees, elbows, scalp, and trunk.
• Guttate psoriasis presents as small red dots of psoriasis that usually appear on the trunk, arms, and legs; the lesions may have some scale. It frequently appears suddenly after an upper respiratory infection (URI).
• Inverse psoriasis occurs on the flexural surfaces, armpit, groin, under the breast, and in the skin folds and is characterized by smooth, inflamed lesions without scaling.
• Pustular psoriasis presents as sterile pustules appearing on the hands and feet or, at times, diffusely, and may cycle through erythema, pustules, and scaling.
• Erythrodermic psoriasis presents as generalized erythema, pain, itching, and fine scaling.
• Scalp psoriasis affects approximately 50% of patients, presenting as erythematous raised plaques with silvery white scales on the scalp.
• Nail psoriasis may cause pits on the nails, which may develop yellowish color and become thickened. Nails may separate from the nail bed.
• Psoriatic arthritis affects approximately 10% of those with skin symptoms. The arthritis is usually in the hands, feet, and, at times, in larger joints. It produces stiffness, pain, and progressive joint damage.
• Oral psoriasis may present with whitish lesions on the oral mucosa, which may appear to change in severity from day to day. It may also present as severe cheilosis with extension onto the surrounding skin, crossing the vermillion border.

Causes

• Lesions of psoriasis are caused by an increase in the turnover rate of dermal cells from the normal 23 days to 3-5 days in affected areas.
• Silver scale on the surface of lesions is a layer of dead skin cells and may be scraped away from most lesions even if the scale is not apparent on visual inspection.
• Patients with psoriasis have a genetic predisposition for the disease.
• • Gene locus has been determined.

  • The trigger event may be unknown in most cases but is likely an immunologic event.

  • Commonly, the first lesion appears after an upper respiratory infection, such as streptococcal pharyngitis.

• Perceived stress can cause exacerbation of psoriasis. Some authors suggest that psoriasis is a stress-related disease and offer findings of increased concentrations of neurotransmitters in psoriatic plaques.
• Autoimmune function
• • Significant evidence is accumulating that psoriasis is an autoimmune disease.

  • Lesions of psoriasis are associated with increased activity of T cells in underlying skin.

  • Guttate psoriasis has been recognized to appear following certain immunologically active events, such as streptococcal pharyngitis, cessation of steroid therapy, and use of antimalaria drugs.

• Superantigens and T cells
• • Psoriasis is related to excess T-cell activity. Experimental models can be induced by stimulation with streptococcal superantigen, which cross-reacts with dermal collagen. This small peptide has been shown to cause increased activity among T cells in patients with psoriasis but not in control groups.

  • Some of the newer drugs used to treat severe psoriasis directly modify the function of lymphocytes.

  • Also of significance is that 2.5% of those with HIV develop psoriasis during the course of the disease.

DIFFERENTIALS

Section 4 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Other Problems to be Considered

Seborrheic dermatitis
Diaper dermatitis
Onychomycosis
Squamous cell carcinoma
Nummular eczema
Lichen planus
Lichen simplex chronicus
Mycosis fungoides
Subcorneal pustulosis
Pustular eruptions

WORKUP

Section 5 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Lab Studies

• Test for rheumatoid factor (RF) is negative.
• Erythrocyte sedimentation rate (ESR) is usually normal.
• Uric acid level may be elevated in psoriasis, causing confusion with gout in psoriatic arthritis.
• Fluid from vesicles or pustules is sterile with lymphocytic infiltrate.
• Perform latex fixation test.
• Perform fungal studies.

Imaging Studies

• Radiographs of affected joints can be helpful in differentiating types of arthritis.
• Bone scans can identify joint involvement early.

Procedures

• Although most cases of psoriasis are diagnosed clinically, some, particularly the pustular forms, can be difficult to recognize. In these cases, dermatologic biopsy can be used to make diagnosis.

TREATMENT

Section 6 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Emergency Department Care

• Patients with guttate, erythrodermic, or pustular psoriasis may present to the emergency department.
• • In each of these cases, restoration of the barrier function of the skin is of prime concern. This can be performed with cleaning and bandaging.

  • Plaque and scalp lesions are frequently encountered in patients seeking care for other problems, and initial treatment of the lesions should be offered.

  • Solar or ultraviolet radiation may be helpful.

  • Oatmeal baths may be helpful.

Consultations

This disease is a chronic problem, and consultation for follow-up with a dermatologist or rheumatologist is appropriate.

• Psoriatic lesions on the palms are especially debilitating and require consultation.
• Patients with infectious diseases and psoriasis may be using drugs that modify immunologic response and render them immunocompromised. Investigation into the type of therapy is important and if such an agent is identified, referral and close follow-up is needed.

MEDICATION

Section 7 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Many drugs that affect the rate of production of skin cells are used in psoriasis therapy alone or in combination with light therapy, stress reduction, and climatotherapy. Adjuncts to treatment include sunshine, moisturizers, and salicylic acid as a scale-removing agent. Generally, these therapies are used for patients with less than 20% of body surface area involved, unless the lesions are physically, socially, or economically disabling.

Treatments for more general or advanced psoriasis include UV-A light, psoralen plus UV-A light (PUVA), retinoids (eg, isotretinoin [Accutane], acitretin [Soriatane]), methotrexate (particularly for arthritis), cyclosporine (Neoral, Sandimmune), infliximab (Remicade), etanercept (Enbrel), and alefacept (Amevive).

The drugs listed below are used for initial treatment.

Drug Category: Topical corticosteroids

These agents are used to reduce plaque formation. These agents have anti-inflammatory effects and may cause profound and varied metabolic activities. In addition, these agents modify the body's immune response to diverse stimuli.

Drug Category: Coal tar

An inexpensive treatment that is available over the counter in shampoos or lotions for use in widespread areas of involvement. It is particularly useful in hair-bearing areas. Some recent research has shown the 1% concentration may be superior in control of lesions to more concentrated preparations.

Drug Category: Keratolytic agents

Used to remove scale, to smooth the skin, and to treat hyperkeratosis.

Drug Category: Vitamin D-3 analogs

Used in patients with lesions resistant to older therapy or with lesions on the face or exposed areas where thinning of the skin would pose cosmetic problems.

Drug Category: Topical retinoids

Aqueous gel formulations are odorless and colorless, and no long-term skin damage has been noted with topical retinoids. There is also no threat of worsening if the therapy is withdrawn, as with steroids. These drugs should not be used in women if pregnancy is a possibility.

FOLLOW-UP

Section 8 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Deterrence/Prevention

• Avoid injury to skin, including sunburn and other physical trauma, as these areas may develop psoriasis. This problem is known as the Koebner phenomenon.


• Avoid drugs known to worsen the problem (eg, chloroquine, beta-blockers, aspirin).

Complications

• Secondary infections


• Psoriatic arthritis


• Mitral valve prolapse

Prognosis

• Lifelong involvement, with waxing and waning, with progression to arthritis in about 10% of cases


• Usually benign


• May be refractory to treatment

Patient Education

• Most psoriasis can be controlled at a tolerable level with the regular application of care measures.


• For excellent patient education resources, visit eMedicine's Psoriasis Center. Also, see eMedicine's patient education articles Psoriasis, What Is Psoriasis?, Types of Psoriasis, Nail Psoriasis, and Understanding Psoriasis Medications. 

MISCELLANEOUS

Section 9 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Medical/Legal Pitfalls

• Abruptly stopping steroid therapy in psoriasis or adding known irritant drugs can result in the sudden worsening of psoriasis or appearance of a new form. Commonly, this new form is guttate psoriasis, which is much more severe and cosmetically problematic than the preexisting plaque type.
• Many of the therapies for psoriasis manipulate the function of the immune system and expose the patient to risk of severe infections while blunting the body's response. In these patients, findings suggestive of minor infections must be taken seriously, and the risk versus the benefit of continuing the drug in the face of the infection must be weighed.

MULTIMEDIA

Section 10 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Media file 1:  Guttate psoriasis erupted in this patient after topical steroid therapy was withdrawn during a pregnancy. Contributed by Randy Park, MD
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Media file 2:  Plaque psoriasis is most common on the extensor surfaces of the knees and elbows. Contributed by Randy Park, MD
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Media type:  Photo

Media file 3:  Plaque psoriasis is raised, roughened, and covered with white or silver scale with underlying erythema. Contributed by Randy Park, MD
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Media type:  Photo

REFERENCES

Section 11 of 11

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

• Bowcock AM. Genetic locus for psoriasis identified. Ann Med. Apr 1995;27(2):183-6. [Medline].
• Bowcock AM, Barker JN. Genetics of psoriasis: the potential impact on new therapies. J Am Acad Dermatol. Aug 2003;49(2 Suppl):S51-6. [Medline].
• Bruce AJ, Rogers RS. Oral psoriasis. Dermatol Clin. Jan 2003;21(1):99-104. [Medline].
• Cuellar ML, Espinoza LR. Psoriatic arthritis. Current developments. J Fla Med Assoc. May 1995;82(5):338-42. [Medline].
• Elder JT, Henseler T, Christophers E, Voorhees JJ, Nair RP. Of genes and antigens: the inheritance of psoriasis. J Invest Dermatol. Nov 1994;103(5 Suppl):150S-153S. [Medline].
• Farber EM, Nall L. Psoriasis. A review of recent advances in treatment. Drugs. Oct 1984;28(4):324-46. [Medline].
• Farber EM. Therapeutic perspectives in psoriasis. Int J Dermatol. Jul 1995;34(7):456-60. [Medline].
• Greaves MW, Weinstein GD. Treatment of psoriasis. N Engl J Med. Mar 2 1995;332(9):581-8. [Medline].
• Lebwohl M. Combining the new biologic agents with our current psoriasis armamentarium. J Am Acad Dermatol. Aug 2003;49(2 Suppl):S118-24. [Medline].
• Lebwohl MG. The evolution of vitamin D analogues for the treatment of psoriasis. Arch Dermatol. Nov 1995;131(11):1323-4. [Medline].
• Lewis HM. Therapeutic progress. II: Treatment of psoriasis. J Clin Pharm Ther. Aug 1994;19(4):223-32. [Medline].
• Menter MA, Krueger GC, Feldman SR, Weinstein GD. Psoriasis treatment 2003 at the new millennium: position paper on behalf of the authors. J Am Acad Dermatol. Aug 2003;49(2 Suppl):S39-43. [Medline].
• Naldi L. Psoriasis. Dermatol Clin. Jul 1995;13(3):635-47. [Medline].
• Pines A, Ehrenfeld M, Fisman EZ, Kaplinsky N, Samra Y, Ronnen M, et al. Mitral valve prolapse in psoriatic arthritis. Arch Intern Med. Jul 1986;146(7):1371-3. [Medline].
• Raychaudhuri SP, Rein G, Farber EM. Neuropathogenesis and neuropharmacology of psoriasis. Int J Dermatol. Oct 1995;34(10):685-93. [Medline].
• Task Force on Psoriasis. Guidelines of care for psoriasis. Committee on Guidelines of Care. Task Force on Psoriasis. J Am Acad Dermatol. Apr 1993;28(4):632-7. [Medline].
• Valdimarsson H, Sigmundsdottir H, Jonsdottir I. Is psoriasis induced by streptococcal superantigens and maintained by M- protein-specific T cells that cross-react with keratin?. Clin Exp Immunol. Jan 1997;107 Suppl 1:21-4. [Medline].
• Weinstein GD. Tazarotene: A novel retinoid for the topical treatment of psoriasis. Pharmacy and Therapeutics. Aug 1997;377-81. [Medline].

Article Last Updated: May 1, 2007