Peripheral spondyloarthritis and psoriatic arthritis; overlaps and distinctions: a report from the GRAPPA 2012 annual meeting.

For over 40 years the concept of psoriatic arthritis (PsA) has slowly evolved as new knowledge has emerged. This has been facilitated by the development of new criteria for classification, improvement on existing criteria by the use of updated methodologies, and new information about the disease. At the same time, there has been discussion about categorization within the generic term spondyloarthritis. At the 2012 annual meeting of the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA), some of this history was reviewed, along with the current thinking about the taxonomy of PsA within spondyloarthritis.