Types of PsA
The diagnosis of psoriatic arthritis (PsA) is largely based on the presentation of the disease in a patient. There are 5 different presentations of PsA, each with its own unique characteristics, although there is considerable overlap1. These different PsA types can present on their own or in combination in a specific patient. Recognizing the pattern is an important step to early diagnosis and targeted treatment. For this reason, patients with psoriasis are often questioned by their health care provider about any joint pain, the joints involved, morning stiffness, or “sausage” digits.
Symmetric
Symmetric polyarticular (poly = many) PsA is characterized by inflammation of five or more joints similarly on both sides of the body. It affects 50% of those suffering from PsA. This type of PsA can affect many joints in the body, and closely resembles rheumatoid arthritis.
Asymmetric
Asymmetric oligoarticular (oligo = few) PsA involves 1-4 joints. This type of PsA impacts different joints on each side of the body. Like symmetric PsA, this type is quite common.
Distal Interphalangeal Predominant PsA
Distal interphalangeal predominant PsA involves inflammation of the distal joints (such as those in the fingers and/or toes closest to the nail bed) and affects about 1 in 10 individuals with PsA. Since the joints closest to the nail beds are most commonly affected, nail changes are especially frequent in this form of PsA. Some common nail changes include pitting, ridges, crumbling, or separation from the nail.
Spondylitis PsA
Spondylitis PsA is also known as Axial PsA. Spondylitis PsA involves inflammation of the spine or at the joints where the spine joins the pelvic bones, which can significantly reduce mobility. Symptoms include pain, stiffness, and reduced mobility of the back or neck.
Supplied by Prof. Raimo Suhonen
Psoriatic Arthritis Mutilans
This uncommon but most severe subtype of PsA is destructive and is characterized by painful deformities in the hands and feet. Loss of bone at the joints may lead to the shortening of fingers and toes. The deformations are significant and cause severe problems with the use of hands or feet. Fewer than 5% of individuals with PsA have arthritis mutilans.
References
1Ritchlin CT, Colbert RA, Gladman DD. Psoriatic Arthritis. N Engl J Med. 2017 Mar 9;376(10):957-970. doi: 10.1056/NEJMra1505557. Erratum in: N Engl J Med. 2017 May 25;376(21):2097. PMID: 28273019.
The Types of PsA section was written by:
Yuliya Lytvyn, PhD Temerty Faculty of Medicine, University of Toronto
Richie Jeremian, PhD Faculty of Medicine & Health Sciences, McGill University