Psoriasis Case 7: Psoriatic arthritis

An obese, 55-year-old Caucasian man with psoriasis for 12 years presented with an 8-month history of painful and swollen joints in the hands, feet, and knees; bilateral heel pain; and morning stiffness of approximately 2-hour duration, unresponsive to nonsteroidal anti-inflammatory drugs (NSAIDs). On physical examination, he had psoriatic plaques on the knees, elbows, genitals, and scalp. The majority of his fingernails showed pitting and onycholysis. Joint evaluation demonstrated multiple tender and swollen joints including the second and third metacarpal-phalangeal joints of both hands; the second, third, and fourth distal interphalangeal joints bilaterally; and both knees. Dactylitis (“sausage digit”) was present on multiple digits in both the hands and the right fourth toe along with a tender and swollen right Achilles tendon. Rheumatoid factor was negative and C-reactive protein was elevated. MTX at 25 mg given orally once weekly along with daily 1 mg of folic acid for 12 weeks failed to adequately control either the joint or skin disease. A TNF-alfa inhibitor was introduced with eventual tapering of MTX to 10 mg once weekly. The patient’s arthritis and skin disease dramatically improved after 4 months of this combination regimen, which was maintained, allowing for significant improvement in his quality of life.  

Discussion

PsA is common in patients with psoriasis. PsA can be disabling with radiographic damage noted in 7% to 47% of patients at a median interval of 2 years despite clinical improvement with standard disease-modifying antirheumatic therapy.184 Because the vast majority of patients with PsA have cutaneous manifestations for up to 12 years before the onset of PsA,185 dermatologists are uniquely positioned to detect the early signs and symptoms of PsA. Patients may also have severe PsA with little to no evident skin disease. Treatment with TNF-alfa-blocking agents can relieve signs and symptoms, inhibit structural damage, and improve quality-of-life parameters in a significant proportion of patients with PsA. Thus dermatologists, in consultation with rheumatologists when necessary, can certainly prevent disability from PsA by initiating the appropriate treatment early on.

The exact proportion of patients with psoriasis who will develop PsA is an area of significant controversy with studies demonstrating a range from 6% to 10% in broadly representative population-based studies to as high as 42% of patients with psoriasis in clinic-based populations.5 Of special interest to dermatologists, the prevalence of PsA increases in patients with more extensive skin disease. The prevalence of PsA in the general population of the United States has been estimated to be 0.1% to 0.25%.186

PsA can develop at any time from childhood on, but for the majority of patients it presents between the ages of 30 and 50 years. PsA affects men and women equally. PsA is characterized by stiffness, pain, swelling, and tenderness of the joints and the surrounding ligaments and tendons. Recurrent early morning stiffness lasting longer than 30 minutes is a valuable question to ask of all patients with psoriasis at each visit when considering the diagnosis of PsA. The enthesis is the anatomic location where tendon, ligament, or joint capsule fibers insert into the bone. Enthesitis may occur at any such site, with common locations including the insertion sites of the plantar fascia, the Achilles tendons, and ligamentous attachments to the ribs, spine, and pelvis. Dactylitis, or “sausage digit,” as seen in our patient, is a combination of enthesitis of the tendons and ligaments along with synovitis involving a whole digit.

Navigate section 6 of the psoriasis guideline: Case-based review

Citation note

Menter A, Korman NJ, Elmets CA,Feldman SR, Gelfand JM, Gordon KB, Guidelines of care for the management of psoriasis and psoriatic arthritis: section 6. Guidelines of care for the treatment of psoriasis and psoriatic arthritis: case-based presentations and evidence-based conclusions. J Am Acad Dermatol. 2011 Jul;65(1):137-74. 



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