Psoriatic Arthritis -- An Overview
by Beth G. Hodges, MD

Psoriatic Arthritis is a rheumatologic disorder that usually occurs to people between the ages of thirty to fifty. It can be broken down into five types:

The first type is asymmetric psoriatic arthritis. This type is the most commonly diagnosed, affecting approximately 70% of sufferers. It can affect any joint and multiple joints at the same time, but they will not be the same joints bilaterally (i.e. won't be both knees but might be a knee on one side and a finger joint on the other.) Affected joints are tender, swollen, and warm to the touch.

The second most common type is symmetric psoriatic arthritis. In this type, the affected joints are the same on both sides of the body (ie both knees.) This type affects females more often than males and is fairly easy to diagnose, as it usually only occurs in conjunction with a severe psoriatic rash. Psoriatic rashes occur classically on extensor surfaces (ie elbows, knees) but can affect skin anywhere on the body and are red, scaly, raised areas of skin.

The third type of psoriatic arthritis is spondylitis. This presents as neck stiffness, low back pain, or pain in the SI joints (where the base of the spine meets the pelvis.)

The fourth type of psoriatic arthritis is distal interphalangeal predominant. It is a more rare type affecting males more than females. This subtype attacks the ends of fingers and toes, often making them appear fattened like sausages. Nails become ridges or pitted and can turn a yellow-orange color.

The fifth type is thankfully the most rare, as it is the most disabling of the subtypes. It is called arthritis mutilans. It deforms and destroys joints in the hands, feet, neck, and back.

Who gets psoriatic arthritis?

There seem to be genetic factors involved, meaning a predisposition for the disease can be passed down through generations, but environmental triggers seem to play a role, such as a virus or bacterial infection that "turns on" the disorder.

Stress can also play a role, and sufferers often report a flare will occur when their stress levels are highest. In other words, a woman can inherit the genes for psoriasis from her mother, but unless some environmental factor "turns on" those genes, the woman will not develop psoriasis.

Alternatively, a mother can have very mild psoriatic symptoms (such as occasional rash) but her daughter may develop severe psoriasis with arthritic involvement. There is no known way currently to predict who in a family will develop psoratic arthritis or how severe it will be. Scientists have noted increased levels of a substance called tumor necrosis factor in the blood of people who suffer from severe psoriasis and psoriatic arthritis, but so far have not been able to correlate levels with any predictive certainty.

Published - October, 2009