A 74-year-old man presents to the dermatology clinic with joint swelling in his hands. The patient is currently receiving therapy with a biologic agent for a chronic skin condition and arthritis. His medical history is positive for myocardial infarction and a recent bout of pneumonia. Examination of his skin reveals no erythematous patches or scaling on the scalp but marked distal joint swelling is noted on all 10 fingers.
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Psoriatic arthritis is a chronic, immune-mediated, inflammatory arthropathy that develops in approximately one-third of patients with psoriasis.1 Psoriasis affects many areas of the body but occurs most commonly on the extensor surfaces of the elbows and knees.2 It affects men and women equally, most commonly between the ages of 40 and 50 years.3 Psoriasis precedes development of arthritis by 10 years on average.4
The pathogenesis of psoriatic arthritis involves an interaction between genetic and environmental factors. Involvement of CD8+ T cells in the development of psoriasis is supported by an association with HLA class I alleles, oligoclonal expansions of CD8+ T cells, and rising incidence in late-stage HIV infection.5 More recent studies have highlighted the involvement of other immune cells such as interleukin (IL)-23 and IL-17 in the development of various spondyloarthropathies.6 Additional risk factors include obesity and nail disease.7
The earliest classification of psoriatic arthritis by Moll and Wright included 5 subtypes8:
- Oligoarticular arthritis, which is asymmetric and involves less than 5 small or large joints
- Polyarticular arthritis, which is usually symmetric and presents like rheumatoid arthritis but involves the distal interphalangeal joint (DIP) and is rheumatoid factor negative
- Distal arthritis, which is highlighted by prominent involvement of the DIP joints
- Arthritis mutilans, which is characterized by a severe destructive joint disease with deformities, especially in hands and feet
- Spondyloarthritis pattern with sacroiliitis and spondylitis that may occur in the absence of peripheral joint disease
Several other conditions such as rheumatoid arthritis, osteoarthritis, pseudogout, and systemic lupus arthritis are included in the differential diagnosis. The diagnosis of psoriatic arthritis is clinical and based on patient history and physical examination and supported by imaging and laboratory evaluation.9 The numerically valued Classification Criteria for Psoriatic Arthritis (CASPAR) criteria can help aid in the diagnosis.10 The criteria consist of psoriasis, either personal or familial; dactylitis or history of dactylitis recorded by a rheumatologist; juxta-articular new bone formation; negative rheumatoid factor; and psoriatic nail dystrophy.
Early detection and treatment are critically important for improving long-term patient outcomes, as the disease can progress rapidly and cause irreversible damage.11 Psoriatic arthritis is associated with comorbidities such as osteoporosis, uveitis, subclinical bowel inflammation, and cardiovascular disease.12 When psoriatic arthritis is identified early, initiation of treatment with targeted therapies can significantly improve symptoms and prevent progression.13
Current treatment recommendations involve the use of nonsteroidal anti-inflammatory drugs, traditional disease-modifying antirheumatic drugs (DMARDs; eg, methotrexate and sulfasalazine), biologics, and small-molecule inhibitors.14 Choice of therapy is best optimized to target symptoms that are most burdensome to each patient.15
Alexandra Stroia, BS, is a medical student at the Lake Erie College of Osteopathic Medicine. Stephen Schleicher, MD, is director of the DermDox Dermatology Centers, associate professor of medicine at Geisinger Commonwealth Medical College, and clinical instructor of dermatology at Arcadia University and Kings College.
- Villani AP, Rouzaud M, Sevrain M, et al. Prevalence of undiagnosed psoriatic arthritis among psoriasis patients: systematic review and meta-analysis. J Am Acad Dermatol. 2015;73:242-248. doi:10.1016/j.jaad.2015.05.001
- Zlatkovic-Svenda M, Kerimovic-Morina D, Stojanovic RM. Psoriatic arthritis classification criteria: Moll and Wright, ESSG and CASPAR — a comparative study. Acta Reumatol Port. 2013;38(3):172-178.
- Husni E, Michael M. Epidemiology of psoriatic arthritis. In: Fitzgerald O, Gladman D, eds. Oxford Textbook of Psoriatic Arthritis. Oxford University Press; 2018.
- Ritchlin CT, Colbert RA, Gladman DD. Psoriatic arthritis [published correction appears in N Engl J Med. 2017;376(21):2097]. N Engl J Med. 2017;376(10):957-970. doi:10.1056/NEJMra1505557
- Fitzgerald O, Winchester R. Emerging evidence for critical involvement of the interleukin-17 pathway in both psoriasis and psoriatic arthritis. Arthritis Rheumatol. 2014;66(5):1077-1080. doi:10.1002/art.38370
- Menon B, Gullick NJ, Walter GJ, et al. Interleukin-17+ CD8+ T cells are enriched in the joints of patients with psoriatic arthritis and correlate with disease activity and joint damage progression. Arthritis Rheumatol. 2014;66(5):1272-1281. doi:10.1002/art.38376
- Ogdie A, Gelfand JM. Identification of risk factors for psoriatic arthritis: scientific opportunity meets clinical need. Arch Dermatol. 2010;146(7):785-788. doi:10.1001/archdermatol.2010.136
- Moll JM, Wright V. Psoriatic arthritis. Semin Arthitis Rheum. 1973;3(1):55-78. doi:10.1016/0049-0172(73)90035-8
- Gottlieb A, Merola JF. Psoriatic arthritis for dermatologists. J Dermatolog Treat. 2020;31(7):662-679. doi:10.1080/09546634.2019.1605142
- Taylor W, Gladman D, Helliwell P, et al. Classification criteria for psoriatic arthritis: development of new criteria from a large international study. Arthritis Rheum. 2006;54(8):2665-2673. 10.1002/art.21972
- Gottlieb AB, Kircik L, Eisen D, et al. Use of etanercept for psoriatic arthritis in the dermatology clinic: the Experience Diagnosing, Understanding Care, and Rreatment with Etanercept (EDUCATE) study. J Dermatolog Treat. 2006;17:343-352. doi:10.1080/09546630600967166
- Sukhov A, Adamopoulos IE, Maverakis E. Interactions of the immune system with skin and bone tissue in psoriatic arthritis: a comprehensive review. Clin Rev Allergy Immunol. 2016;51(1):87-99. doi:10.1007/s12016-016-8529-8
- Gladman DD, Antoni C, Mease P, Clegg DO, Nash P. Psoriatic arthritis: epidemiology, clinical features, course, and outcome. Ann Rheum Dis. 2005;64 (Suppl 2):ii14–ii17. doi:10.1136/ard.2004.032482
- Coates LC, Kavanaugh A, Mease PJ, et al. Group for research and assessment of psoriasis and psoriatic arthritis 2015 treatment recommendations for psoriatic arthritis. Arthritis Rheumatol. 2016;68(5):1060-1071. doi:10.1002/art.39573
- Gossec L, Smolen JS, Ramiro S, et al. European League Against Rheumatism (EULAR) recommendations for the management of psoriatic arthritis with pharmacological therapies: 2015 update. Ann Rheum Dis. 2016;75(3):499-510. doi:10.1136/annrheumdis-2015-208337