| Psoriatic arthritis | |
|---|---|
| Other names | Arthritis psoriatica, arthropathic psoriasis, psoriatic arthropathy |
 | |
| Severe psoriatic arthritis of both feet and ankles. Note the changes to the nails. | |
| Specialty | Rheumatology |
Psoriatic arthritis (PsA) is a long-term inflammatory arthritis that occurs in people affected by the autoimmune disease psoriasis.[1][2] The classic feature of psoriatic arthritis is swelling of entire fingers and toes with a sausage-like appearance ("sausage digit").[3] This often happens in association with changes to the nails such as small depressions in the nail (pitting), thickening of the nails, and detachment of the nail from the nailbed.[3] Skin changes consistent with psoriasis (e.g., red, scaly, and itchy plaques) frequently occur before the onset of psoriatic arthritis but psoriatic arthritis can precede the rash in 15% of affected individuals.[3] It is classified as a type of seronegative spondyloarthropathy.
Genetics are thought to be strongly involved in the development of psoriatic arthritis.[3] Obesity and certain forms of psoriasis are thought to increase the risk.[3]
Psoriatic arthritis affects up to 30% of people with psoriasis and occurs in both children and adults.[3] Approximately 40–50% of individuals with psoriatic arthritis have the HLA-B*27 genotype.[3] The condition is less common in people of Asian or African descent and affects men and women equally.[3]
- ^ Freedberg, Irwin M., Fitzpatrick, Thomas B. (2003). Fitzpatrick's dermatology in general medicine (6th ed.). New York: McGraw-Hill. pp. 427–436. ISBN 978-0-07-138076-8.
- ^ James, William, Berger, Timothy, Elston, Dirk (2005). Andrews' Diseases of the Skin: Clinical Dermatology (10th ed.). Saunders. p. 194. ISBN 978-0-7216-2921-6.
- ^ a b c d e f g h Ritchlin CT, Colbert RA, Gladman DD (March 2017). "Psoriatic Arthritis". New England Journal of Medicine (Review). 376 (10): 957–70. doi:10.1056/NEJMra1505557. PMID 28273019. S2CID 43867408.