• Home

Home > Medical Reference > Patient Education

• Highlights
• Introduction
• Causes
• Risk Factors
• Prognosis
• Diagnosis
• Treatment
• Topical Medications
• Other Medications
• Phototherapy
• Managing Psoriasis
• Resources
• References

Psoriasis

Description

An in-depth report on the causes, diagnosis, treatment, and prevention of psoriasis.

Diagnosis

A microscopic examination of tissue taken from the affected skin patch is required to make a definitive diagnosis of psoriasis and to distinguish it from other skin disorders. Usually in psoriasis, the examination will show a large number of dry skin cells, but without many signs of inflammation or infection. Changes in the nails typical of psoriasis are often strong indicators of psoriasis.

Ruling Out Other Conditions

Distinguishing Psoriasis Patches from Other Disorders. Several conditions produce symptoms that resemble those of psoriasis. Examples include:

• Seborrheic psoriasis is hard to distinguish from seborrheic dermatitis (dandruff is one form of this condition). Seborrheic dermatitis patches are usually greasy, yellowish, and crusty. Nail involvement may also help differentiate psoriasis.
• Generalized erythrodermic psoriasis may be confused with drug allergic reactions, atopic eczema, and symptoms of lymphomas.
• Fungal infections, other skin conditions, or circulation problems may also cause nail changes typical of psoriasis.

Distinguishing Psoriatic Arthritis from Other Conditions. Psoriatic arthritis may resemble the following:

• Rheumatoid arthritis (RA). As in rheumatoid arthritis, psoriatic arthritis can cause pain or tenderness in one or more joints, and morning stiffness is common. People with psoriatic arthritis, however, lack a particular antibody, called rheumatoid factor, which is found in the blood of many people with rheumatoid arthritis.
• Systemic lupus erythematosus (SLE). Symptoms of SLE may include both a psoriasis-like rash and arthritis, which could make the diagnosis difficult.
• Reiter's disease. Reiter's disease is a syndrome that includes arthritis and inflammation in the eyes and urinary tract. It also causes skin lesions that are very similar to psoriasis, which are usually raised patches on the lips, penis, palms, and soles.
• Gout. Gout causes pain, often in the fingers and toes.

Some evidence now indicates that inflammation in psoriatic arthritis may be distinguished from other arthritic conditions by its occurrence in sites where muscle tissue inserts into the bone (called enthesitis ) rather than in the joint, which is a common site in other inflammatory arthritic conditions.

• Review Date: 10/30/2006
• Reviewed By: Harvey Simon, M.D., Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is the first of its kind, requiring compliance with 53 standards of quality and accountability, verified by independent audit. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial process . A.D.A.M. is also a founding member of Hi-Ethics (www.hiethics.com) and subscribes to the principles of the Health on the Net Foundation (www.hon.ch).

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997-2007 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.