Psoriatic is characterized by inflammation of the skin, which is the psoriasis part and inflammation of the joints, which is the arthritis part. Psoriatic Arthritis affects approximately 2% of the Caucasian population living in the U.S. It looks like patchy, reddened skin with inflamed and scaling areas. It can appear on the elbows, knees, scalp, navel, genitals, and basically anywhere you have skin. When an individual has psoriasis and also complains of inflamed, painful and sore joints they are diagnosed with psoriatic arthritis.
Usually this diagnosis is made at ages 40s or 50s with both males and females being affected. Most of the patients are diagnosed with psoriasis first and arthritis later in life but 15% of those with the disease were diagnosed with arthritis first.
Psoriatic arthritis is a systemic rheumatic disease. It causes inflammation of body tissues surrounding the joints as well as the skin. Tissues that may also be involved are the eyes, lungs, kidneys and the heart.
Like psoriasis, the cause of psoriatic arthritis is unknown. It is suspected that a combination of immune deficiencies and genetics play a role in the disease as well as possible environmental issues. Heredity is suspected because certain genes have been found to be common in those who have psoriatic arthritis including the HLA-B27 gene marker. There exists a blood test to determine if this gene marker is present in the blood.
Individuals with psoriatic arthritis usually have arthritis in the knees, ankles, and the joints of the feet. Typically only a few of these joints are inflamed at any one time. Inflammation causes pain and stiffness. If the inflammation is in the finger or toe the entire digit can swell giving the appearance of a sausage. Usually the individual is stiffer in the morning but the stiffness eases with movement.
A common development for those with psoriatic arthritis is to have some involvement of inflammation in the tendons called "tendonitis". The tendons surround the cartilage. When inflammation is in the tendon located behind the heel, it is called Achilles tendonitis. This type of tendon involvement makes it painful for the individual to walk or climb stairs.
Psoriatic arthritis can mimic rheumatoid arthritis because it can affect many different joints at the same time in a symmetrical fashion.
Psoriatic arthritis can also spread to inflammation in other organs such as the aorta artery of the heart, the lungs, and the eyes.
Those who have psoriatic arthritis often also have acne and nail psoriasis.
When making the diagnosis, the doctor may order laboratory tests as well as to make the diagnosis based on clinical observations and medical history from the patient. The blood tests: sedimentation rate, and the rheumatoid factor test are performed to check for elevation of cells to reflect inflammation of joints and to exclude the disease rheumatoid arthritis.