Psoriatic arthritis belongs to a group of diseases that are referred to collectively as spondylo arthritis. To find more information on psoriatic arthritis a disease characterized by both skin and joint manifestations, go to the "About Psoriatic Arthritis," section of the Spondylitis Association of America web site.

Lymphoma encompasses a variety of cancers of the lymphatic system, according to the Leukemia and Lymphoma Society. They generally start in lymph nodes or collections of lymphatic tissue in organs like the stomach or intestines, and may involve the marrow and the blood in some cases.

Latest Research Findings
Researchers from the University of Pennsylvania in Philadelphia looked at a random sample of patients from a British database that holds medical records for over eight million people. The records covered people 65 or older who were treated between 1988 and 1996.

“Patients with psoriasis had an almost three-fold increased rate of lymphoma compared with patients without psoriasis,” stated the authors. “Patients 65 years or older who had psoriasis developed an additional 122 lymphomas per 100,000 patients annually.”

Previous research indicated that people with psoriasis were at higher risk of developing lymphoma, but no one had measured the degree of the risk.