Psoriasis is a chronic auto-immune skin condition, which in essence is due to the increased and excessive growth cycle of skin cells. There are five types of psoriasis: plaque, guttate, inverse, pustular and erythrodermic. The most common form, plaque psoriasis, presents as a red patch of thickened skin with overlying scaliness, due to the rapid turnover rate of skin cells. These plaques occur mostly on the elbows and knees, scalp, palms of hands and soles of feet, and genitals. A variety of factors -- ranging from emotional stress and trauma to streptococcal infection -- can cause an episode of psoriasis. These external stressors serve as triggers for an inherited defect in immune function and so causes the immune system to react.
Psoriasis can also cause inflammation of the joints, which is known as psoriatic arthritis. Between 10% and 40% of all people with psoriasis have psoriatic arthritis. You may develop psoriatic arthritis if you have a strong family history of psoriasis or psoriatic arthritis.
Psoriatic arthritis involves joint and connective tissue inflammation. Psoriatic arthritis can affect any joint, but is most common in the joints of the fingers and toes. This can result in a sausage-shaped swelling of the fingers and toes known as dactylitis. You may also develop swelling and deformities in your hands and feet before having significant joint symptoms. Psoriatic arthritis can also affect the hips, knees and spine (spondylitis). Joint pain, stiffness and swelling are the main symptoms of psoriatic arthritis. When the spine is affected, the symptoms are stiffness, burning, and pain, most often in the lower spine and sacrum.
Both psoriatic arthritis and psoriasis are chronic diseases that get worse over time, but you may have periods when your symptoms improve or go into remission alternating with times when symptoms become worse. Nevertheless, there are treatments and options available for management of psoriatic arthritis. It is vital to get treatment as early as possible to prevent the chronic deformities which can occur.