Types of Psoriasis:

Various forms of psoriasis exist. Some can occur alone or at the same time as other types, or one may follow another. The most common type is called plaque psoriasis, also known as psoriasis vulgaris.

Plaque Psoriasis

Plaque psoriasis leads to skin patches that start off in small areas, about one-eighth of an inch wide. They usually appear in the same areas on opposite sides of the body.

The patches slowly grow larger and develop thick, dry plaque. If the plaque is scratched or scraped, bleeding spots the sizes of pinheads appear underneath. This is known as the Auspitz sign.

Some patches may become ring shaped (annular), with a clear center and scaly raised borders that may appear wavy and snake-like.

As the disease progresses, eventually separate patches may join together to form larger areas. In some cases, the patches can become very large and cover wide areas of the back or chest. This is known as geographic plaques because the skin lesions resemble maps.

Plaque psoriasis may persist for long periods of time. More often it flares up periodically, triggered by certain factors such as cold weather, infection, or stress.

Patches most often occur on the:

• Elbows
• Knees
• Lower back

They may also be seen on the:

• 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.

Psoriatic Arthritis

Psoriatic arthritis (PsA) is an inflammatory condition that leads to stiff, tender, and inflamed joints. Estimates on its prevalence among those with psoriasis range from 2 - 42%. AIDS patients and those 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.

Although patients with psoriatic arthritis tend to have mild skin symptoms, the disease affects the entire body. PsA, therefore, is more serious than the more common plaque psoriasis. Infrequently, the course of PsA has been associated with a syndrome known by the acronym SAPHO, which stands for:

• Synovitis (inflammation in the joints)
• Acne
• Pustule eruptions
• Hyperostosis (abnormal bony growths)
• Osteolysis (bone destruction)

Some experts group PsA 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 and should not be considered as a way to delay this type of psoriasis.