1Memorial University of Newfoundland Faculty of Medicine, St. John’s, NL, Canada
2Nexus Clinical Research, St. John’s, NL, Canada
Early diagnosis of psoriatic arthritis (PsA) is essential for preventing disease progression and joint destruction. The majority of patients develop PsA years after the onset of their skin disease. Therefore, dermatologists are in a strategic position to make the diagnosis of PsA, and either manage it or refer the patient to a rheumatologist in order to prevent the potentially irreversible destruction of the affected joints. We will review the presentation and temporal relationship of psoriasis and PsA, the diagnosis, classification, and management, in addition to the role of the dermatologist in the early detection of PsA.
Distal interphalangeal joint (DIP), metatarsophalangeal joint (MTP), psoriasis, psoriatic arthritis, PsA
Psoriatic arthritis (PsA) is often described as a chronic, inflammatory arthropathy affecting the distal interphalangeal joints (DIP) of the hands, metatarsophalangeal joints (MTP)
of the feet, and spine in association with psoriasis.1 One to three percent of the world population has been diagnosed with psoriasis.2
Estimates of the prevalence of PsA within the psoriasis population range from 6%-39%.3 The Psoriasis Foundation 2001 Benchmark Survey estimated the prevalence of PsA in patients with psoriasis to be as high as 23%.4 PsA is often under diagnosed or misdiagnosed, and therefore, statistics may be misrepresented.
There appears to be great variability in the case definition for PsA. One such definition, proposed by Moll and Wright, defines PsA as “an inflammatory arthritis associated with
psoriasis and usually with a negative serological test for rheumatoid arthritis.”5 Due to the broad spectrum of PsA there has been a need to create subgroups (Table 1).
Characteristic features of psoriatic arthritis include: swelling, erythema, warmth, and inflammation of the affected joint. PsA can present with asymmetrical joint distribution,
involving more joints over time and progressing as an oligoarticular/polyarticular disease. Almost any joint can be involved including peripheral (e.g., the DIPs) and/ or axial joints (e.g., spine and sacroiliac joints). PsA can also manifest with involvement of periarticular structures such as tenosynovitis (inflammation of the tendon sheath), dactylitis or “sausage digit” (inflammation of entire digit), and enthesitis (insertion of the tendon).4
As with other sero-negative spondylarthropathies, there can also be extra-articular manifestations of PsA. These features may include inflammation of the eye, mucous
membranes, urinary system, and cardiovascular system (i.e., iritis, conjunctivitis, aortic dilation, and urethritis).6
There does not appear to be a difference in the prevalence of psoriasis between the sexes,7 however, the onset of disease seems to be earlier in women.8 The onset of psoriasis is bimodal with a median age of onset at 29.1 years.9 Those with early disease can have a greater body surface area involved, unstable psoriasis, frequent relapses, and a higher incidence of guttate psoriasis and nail involvement.9,10
Patients with later onset tend to have a more stable course and less severe disease, but more frequent palmoplantar pustulosis.9,10
|Form of PsA||Frequency||Joint Distribution||Other Features|
|Oligoarticular asymmetrical arthritis||70%||< 4 joints||dactylitis and/or monoarthritis|
|Symmetrical polyarthritis||15%||5 joints||erosive and metacarpophalangeal joint involvement|
|Predominantly DIP arthritis||5%||severe nail psoriasis|
|Arthritis mutilans||5%||May not have severe general disease||telescoping of fingers and toes, often associated with sacroiliitis|
|Spinal form||5%||Sacroiliitis||can be asymptomatic, uni/bilateral sacroiliitis, +/- peripheral joints|
|Table 1: PsA classification subgroups (proposed by Moll and Wright5)|
DIP = PsA in the distal interphalangeal joints of the hands observations.
|Clinical Feature||Psoriatic Arthritis||Rheumatoid|
|Most common joint pattern||Oligoarticular/|
|DIP joint||High||Low||Does not occur||Does not occur||Does not occur|
|Dactylitis||High||Does not occur||Low||Medium||Low|
|Enthesitis||Medium||Does not occur||Medium||High||Medium|
|Spondylitis||Medium||Does not occur||High||Low||Medium|
|Sacroiliitis||Asymmetric||Does not occur||Symmetric||Asymmetric||Symmetric|
|Skin/nail lesion||High||Does not occur||Does not occur||Medium||Does not occur|
|Rheumatoid factor positive||Does not occur||High||Does not occur||Does not occur||Does not occur|
|Table 2: Clinical features in psoriatic arthritis and other seronegative arthropathies (adapted from Brockbank and Gladman17)|
DIP = PsA in the distal interphalangeal joints of the hands
The temporal sequence of disease onset can vary, making the diagnosis of PsA difficult. As high as 75%-80% of psoriasis patients will present with cutaneous manifestation 5-10 years prior to the onset of joint complaints.4,11 There can exist a flare in arthritis with or without a coinciding flare of psoriasis.4
The majority of patients with PsA have mild or moderate cutaneous manifestation,12 and 80%-90% of this population have nail lesions.12,13 However, 46% of patients with psoriasis (no affected joints) have nail involvement.13 The extent and severity of both skin and joint disease correlate closely with the severity of psoriatic nail involvement, however this association is more commonly found in the DIP arthritis form of PsA.14
Distinguishing PsA from other inflammatory conditions can be challenging since the clinical features may overlap. The differential diagnosis may include: rheumatoid arthritis (RA), reactive arthritis, inflammatory bowel disease (IBD) and ankylosing spondylitis, to name a few. (See Table 2.)
To further complicate matters, other rheumatologic conditions such as osteoarthritis, soft tissue rheumatism, septic arthritis, and true RA can coexist with psoriasis. In addition, psoriasis has been found to occur with higher frequency in patients with IBD and ankylosing spondylitis.15,16,17
The presence of such confounding variables stresses the importance of a full history and physical examination that includes serological, radiological, and perhaps genetic investigations to aid in the diagnosis.
Making the Diagnosis
There exist several PsA classification criteria in the literature. The Classification criteria for Psoriatic Arthritis (CASPAR) are newly developed criteria for the diagnosis of PsA. They are simple to use, have a high specificity of 98.7%, and a sensitivity of 91.4% for the diagnosis of PsA.18
A patient must have inflammatory articular disease (joint, spine, or entheseal) with 3 or more of the following 5 criteria:
- Current OR personal history of psoriasis, OR family history of psoriasis (1st or 2nd degree relative). Psoriasis is defined as skin or scalp disease.
- Psoriatic nail disease including: onycholysis, pitting, hyperkeratosis on current physical exam
- Negative for rheumatoid factor (by any method except latex)
- History of or current dactylitis recorded by a rheumatologist
- Radiographic evidence of juxta-articular new bone formation, appearing as ill defined ossification near joint margins (but excluding osteophyte formation) on plain radiographs of the hand or foot.
Based on these criteria and established clinical features of PsA, a basic workup for a new patient in your office with psoriasis should include a history, physical examination, laboratory investigations, and review of treatment options as summarized below.
|Type of Psoriasis||Characteristics||Area Involved||Lesion|
(Size and Symmetry)
|Other Findings & Complications|
|Plaque (80%)||Erythematous plaques with|
raised, sharp defined margins
and thick silvery scales
elbows, knees, and
|Nail pitting, possible umbilicus and|
intergluteal cleft involvement
|Pustular (<3%)||Erythema, scaling, sheets|
of superficial pustules with
erosions; variety of subtype
|Malaise, fever, diarrhea, leukocytosis,|
hypocalcemia, hepatic involvement;
can be severe and life threatening;
associated with pregnancy, infection,
and oral glucocorticoids
|Scalp (79%)||Erythematous plaques with|
raised, sharp defined margins
and thick silvery scales
|Can extend to|
the forehead and
auricular area or as
a patch on occiput
|May have fissuring of superior and|
posterior auricular folds
|Guttate||Abrupt onset, multiple small|
the palms and soles
|shaped papule||Associated with Streptococcus|
infection, usually pharyngitis
exfoliation of fine scales
without plaque or guttate
|Head to toe||Generalized||Complications due to loss of adequate|
barrier, such as infection, sepsis,
fluid loss (electrolyte abnormalities);
associated with stress, medications,
burns with phototherapy and infection
|Palmoplantar||Tender, erythrodermic, dry|
scaling patches or thickening
|Palms and soles||Pustules and|
|Less severe form of pustular psoriasis|
|Inverse (Flexural)||Salmon red color with|
defined margins, minimal
|Eczema can also be present;|
perspiration can irritate fissures and
|Table 3: Clinical manifestations of psoriasis8,19|
- Current OR personal history of psoriasis, OR family history of psoriasis
- Swelling of joints
- Pain or tenderness in joints
- Morning stiffness >30 minutes
- Functional capacity in activities of daily living (changes in ability to function at home and at work and impact on quality of life), etc.
• Nails: evidence of onycholysis, pitting, hyperkeratosis, oil-drop sign, and nail crumbling
• Skin: see Table 1.
- Signs of joint inflammation such as swelling, effusion, synovial thickening, erythema, decrease in range of movement
- Other manifestations: DIP joint involvement, enthesis, dactylitis, spondylitis and sacroiliitis, eye symptoms (i.e., iritis), etc.
- See Table 1 for other characteristic findings for PsA.
- Laboratory tests should include: complete blood count, erythrocyte sedimentation rate, C-reactive protein, Rh factor, and routine renal and liver function tests.
- Plain radiographs: these can be normal in the early stages of disease. However, juxta-articular new bone formation, periarticular osteopenia, and later stages may demonstrate “pencil in cup” erosive disease in the hands or feet.
When treating the cutaneous and joint manifestations, as in PsA, each aspect of the disease must be considered. The 2 may be treated independently, although a number of
systemic therapies may benefit both. Treatment options that can improve both PsA and psoriasis include:
1. Traditional systemic agents
- Cyclosporine (3-5mg/kg PO daily)
- Methotrexate (doses ranging from 15-25mg PO/IM weekly)
2. Biologic agents (with indication for PsA)
- Etanercept (50mg SC bi-weekly)
- Infliximab (5mg/kg IV at week 0, 2, 6 and then every8 weeks)
- Adalimumab (40mg SC every 2 weeks)
However, some may help one while adversely affecting the
other. Drugs that can induce disease exacerbation include:20
1. Drugs that treat arthritis, but may worsen psoriasis
- Systemic corticosteroids
2. Drugs that treat psoriasis, but may worsen arthritis
The Role of the Dermatologist
The recognition and early treatment of PsA is analogous to that of acne. We are aware of the importance of early recognition of acne and the urgency in treating it aggressively in order to induce remission and prevent further damage. The destruction of the joints in PsA follows the same principle: treat early to prevent the damage. The dermatologist who monitors a psoriatic patient can detect PsA at its earliest stage.
A study by Zanolli and Wikle concluded that a large portion of patients with psoriasis presenting to a dermatologist for treatment were recognized to have coexisting joint complaints; and the prevalence of PsA is greater than that identified by a nondermatologist.21
The prevalence of psoriasis is greater than PsA, and psoriasis typically precedes the joint complaints.4,11,22 Therefore, the dermatologist is in a unique position to screen patients with
psoriasis for PsA by maintaining a high index of suspicion and close follow-up. In limited cases, consultation with a rheumatologist may be necessary to make the diagnosis of PsA.
A screening questionnaire could be designed for patients presenting to the dermatologist for the first time with psoriasis. The Psoriasis and Arthritis Screening Questionnaire (PASQ)23 that was developed by our group was created using the CASPAR criteria as its framework. This questionnaire does not replace a proper history, but reminds us to consider the diagnosis of PsA in any patient with symptoms of psoriasis, regardless of the severity of the cutaneous
The dermatologist is in a strategic position for early diagnosis, intervention, and appropriate management of the patient with PsA at its onset. The skin and joint involvement
in PsA can significantly affect a patient’s function and quality of life, and may increase cardiovascular morbidity and mortality.24 These effects, in turn, may have significant impact on the family and society in general. Early diagnosis and effective therapy for PsA can prevent the progression of joint damage, and possibly induce a remission of the disease.
- Stern RS. The epidemiology of joint complaints in patients with psoriasis. J Rheumatol 12(2):315-20 (1985 Apr).
- Myers WA, Gottlieb AB, Mease P. Psoriasis and psoriatic arthritis: clinical features and disease mechanisms. Clin Dermatol 24(5):438-47 (2006 Sep-Oct).
- Gelfand JM, Gladman DD, Mease PJ, et al. Epidemiology of psoriatic arthritis in the population of the United States. J Am Acad Dermatol 53(4):573 (2005 Oct).
- Qureshi AA, Husni ME, Mody E. Psoriatic arthritis and psoriasis: need for a multidisciplinary approach. Semin Cutan Med Surg 24(1):46-51 (2005 Mar).
- Moll JM, Wright V. Psoriatic arthritis. Semin Arthritis Rheum 3(1):55-78 (1973).
- Weinstein GD, Gottlieb AB, editors: Therapy of Moderate to Severe Psoriasis, 2nd ed. New York: Marcel Dekker, (2003).
- Lebwohl M. Psoriasis. Lancet 361(9364):1197-204 (2003 Apr 5).
- Myers W, Opeola M, Gottlieb AB. Common clinical features and disease mechanisms of psoriasis and psoriatic arthritis. Curr Rheumatol Rep 6(4):306-13 (2004 Aug).
- Ferrandiz C, Pujol RM, Garcia-Patos V, et al. Psoriasis of early and late onset: a clinical and epidemiologic study from Spain. J Am Acad Dermatol 46(6):867-73 (2002 Jun).
- Henseler T, Christophers E. Psoriasis of early and late onset: characterization of two types of psoriasis vulgaris. J Am Acad Dermatol 13(3):450-6 (1985 Sep).
- Alenius GM. Psoriatic arthritis-new insights give new options for treatment. Curr Med Chem 14(3):359-66 (2007).
- Cohen MR, Reda DJ, Clegg DO. Baseline relationships between psoriasis and psoriatic arthritis: analysis of 221 patients with active psoriatic arthritis. Department of Veterans Affairs Cooperative Study Group on Seronegative Spondyloarthropathies. J Rheumatol 26(8):1752-6 (1999 Aug).
- Gladman DD, Anhorn KA, Schachter RK, et al. HLA antigens in psoriatic arthritis. J Rheumatol 13(3):586-92 (1986 Jun).
- Williamson L, Dalbeth N, Dockerty JL, et al. Extended report: nail disease in psoriatic arthritis–clinically important, potentially treatable and often overlooked. Rheumatology (Oxford) 43(6):790-4 (2004 Jun).
- Yates VM, Watkinson G, Kelman A. Further evidence for an association between psoriasis, Crohn’s disease and ulcerative colitis. Br J Dermatol 106(3):323-30 (1982 Mar).
- Hellgren L. Association between rheumatoid arthritis and psoriasis in total populations. Acta Rheum Scand 15:316-26 (1969).
- Brockbank J, Gladman D. Diagnosis and management of psoriatic arthritis. Drugs 62(17):2447-57 (2002).
- Taylor W, Gladman D, Helliwell P, et al. Classification criteria for psoriatic arthritis: development of new criteria from a large international study. Arthritis Rheum 54(8):2665-73 (2006 Aug).
- Gladman DD. Clinical Manifestations and diagnosis of psoriatic arthritis. In: UpToDate online 2007 version 15.3.
- Soriano ER, McHugh NJ. Therapies for peripheral joint disease in psoriatic arthritis. A systematic review. J Rheumatol 33(7):1422-30 (2006 Jul).
- Zanolli MD, Wikle JS. Joint complaints in psoriasis patients. Int J Dermatol 31(7):488-91 (1992 Jul).
- Thumboo J, Uramoto K, Shbeeb MI, et al. Risk factors for the development of psoriatic arthritis: a population based nested case control study. J Rheumatol 29(4):757-62 (2002 Apr).
- Kraishi M, Heale C, Landells I, et al. The Psoriasis and Arthritis Screening Questionnaire (PASQ): a sensitive and specific tool to diagnose psoriatic arthritis patients with high correlation to the CASPAR criteria. Accepted for presentation at the 83rd Annual Conference of the Canadian Dermatology Association, June 27-July 2, 2008, Montréal, QC.
- Gelfand JM, Neimann AL, Shin DB, et al. Risk of myocardial infarction in patients with psoriasis. JAMA 296(14):1735-41 (2006 Oct 11).