Monday, February, 13, 2012

Psoriasis - Causes

Table of Contents

  • Upper pelvic bone area
  • Bottom of the feet
  • Calves and thighs
  • Genital areas
  • Palms of the hands

Psoriasis of the scalp affects about 50% of patients. In some cases, the psoriasis may cover the scalp with thick plaques that extend down from the hairline to the forehead.

Psoriasis patches rarely affect the face in adulthood. In children, psoriasis is most likely to start in the scalp and spread to other parts of the body. Unlike in adults, it also may occur on the face and ears.

Less Common Forms of Psoriasis

Psoriasis Form

Description of Skin Patches

Comments

Guttate Psoriasis

The patches are teardrop-shaped and appear suddenly, usually over the trunk and often on the arms, legs, or scalp. They often disappear without treatment.

Guttate psoriasis can occur as the initial outbreak of psoriasis, often in children and young adults 1 - 3 weeks after a viral or bacterial (usually streptococcal) respiratory or throat infection. A family history of psoriasis and stressful life events are also highly linked with the start of guttate psoriasis.

Guttate psoriasis can also develop in patients who have already had other forms of psoriasis, most often in people treated with widely-applied topical (rub-on) products containing corticosteroids.

Inverse Psoriasis

Patches usually appear as smooth inflamed areas without a scaly surface. They occur in the folds of the skin, such as under the armpits or breast, or in the groin.

Inverse psoriasis may be especially difficult to treat.

Seborrheic Psoriasis

Patches appear as red scaly areas on the scalp, behind the ears, above the shoulder blades, in the armpits or groin, or in the center of the face.

Seborrheic psoriasis may be especially difficult to treat.

Nail Psoriasis

Tiny white pits are scattered in groups across the nail. Toenails and sometimes fingernails may have yellowish spots. Long ridges may also develop across and down the nail.

The nail bed often separates from the skin of the finger and collections of dead skin can build up underneath the nail.

Over half of patients with psoriasis have abnormal changes in their nails, which may appear before other skin symptoms. In some cases, nail psoriasis is the only symptom. Nail psoriasis is linked to psoriatic arthritis.

Generalized Erythrodermic Psoriasis (also called psoriatic exfoliative erythroderma)

This is a rare and severe form of psoriasis, in which the skin surface becomes scaly and red. The disease covers all or nearly all of the body.

About 20% of such cases evolve from psoriasis itself. The condition may also be triggered by certain psoriasis treatments, and other medications such as corticosteroids or synthetic antimalarial drugs.

Pustular Psoriasis

Patches become pus-filled and blister-like. The blisters eventually turn brown and form a scaly crust or peel off.

Pustules usually appear on the hands and feet. When they form on the palms and soles, the condition is called palmar-plantar pustulosis.

Pustular psoriasis may erupt as the first occurrence of psoriasis, or it may evolve from plaque psoriasis.

A number of conditions may trigger pustular psoriasis, including infection, pregnancy, certain drugs, and metal allergies.

Pustular psoriasis can also accompany other forms of psoriasis and can be very severe.

Psoriatic Arthritis

Psoriatic arthritis (PsA) is an inflammatory condition that leads to stiff, tender, and inflamed joints. Estimates on its prevalence among people with psoriasis range from 2 - 42%. Psoriasis patients who also have AIDS and people with severe psoriasis are at higher risk for developing PsA.

About 80% of PsA patients have psoriasis in the nails. Arthritic and skin flare-ups tend to occur at the same time. It is not clear whether psoriatic arthritis is a unique disease or a variation of psoriasis, although evidence suggests they are both caused by the same immune system problem.

PsA is often divided into five forms. The forms differ according to the location and severity of the affected joint:

  • Symmetric PsA: Symptoms occur in the same location on both sides of the body. The condition usually affects multiple joints. In about half of the cases, symmetric PsA will get worse. The condition is very similar to, but less disabling than, rheumatoid arthritis. The psoriasis itself is often severe.
  • Asymmetric PsA: This form involves periodic joint pain and redness, usually in only one to three joints, which can be the knee, hip, ankle, wrist, or one or more fingers. The pain does not occur in the same location on both sides of the body.
  • Distal interphalangeal predominant (DIP): DIP involves the joints of the fingers and toes closest to the nail. It occurs in about 5% of PsA cases.
  • PsA in the spine: Inflammation in the spinal column (spondylitis) is the primary symptom in about 5% of PsA cases. Such patients may have stiffness and burning sensations in the neck, lower back, sacroiliac, or spinal vertebrae. The spine can be involved in many patients with PsA, even though stiffness and burning sensations in these areas are not the primary symptoms. When it affects the spine, psoriatic arthritis most frequently targets the sacrum (the lowest part of the spine). Movement is difficult.
  • Arthritis mutilans: This is a severe, deforming, and progressive form of arthritis. It affects less than 5% of PsA cases. It mainly affects the small joints of the hands and feet, but it can also be found in the neck and lower back. Arthritic and skin flares and remissions tend to coincide.

People who start to smoke after developing psoriasis may delay the onset of psoriatic arthritis. However, research has also linked smoking to an increased risk of psoriasis, and because smoking causes serious health problems, it should not be considered as a way to delay this type of psoriasis.


Review Date: 10/21/2010
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)