Start With One Question at Every Psoriasis Visit
With roughly 30% of plaque psoriasis patients developing psoriatic arthritis (PSA) and no single confirmatory test, PA Buchi Neita and PA Jennifer Connor open by asking their guest, Dr. April Armstrong, how she screens in a busy clinic. Her answer is refreshingly simple: start with one triage question — when patients wake up in the morning, do they feel stiffness in their joints or back?
Armstrong explains the logic. PSA is an inflammatory arthritis, which distinguishes it from degenerative arthritis like osteoarthritis. Inflammatory joints feel worse with rest and better with activity, so morning is the ideal time to ask. If that stiffness lasts longer than 30 minutes, it suggests inflammatory arthritis and should prompt a targeted joint exam and further workup. Osteoarthritis behaves the opposite way — the joints feel worse with activity.
She also reminds clinicians to make the link for patients. In about 75–80% of cases, psoriasis predates PSA; in roughly 10% the conditions appear concurrently; and in the remaining ~10%, arthritis actually precedes the skin lesions. Because patients rarely connect their joints to their skin, Armstrong argues that dermatology clinicians should ask about joints at every visit.
The Focused Exam and Targeted Workup
Once morning stiffness is established, Armstrong lets the patient's reported symptoms guide her joint exam, paying close attention to peripheral joints in the hands and toes — including the PIP and DIP joints, which are frequently affected in PSA. She palpates with enough pressure to blanch about a third of her own thumbnail; that whitening tells her she's applying adequate force to elicit tenderness.
Beyond the joints, she looks for enthesitis — heel pain and inflammation of the Achilles tendon — and dactylitis, the 'sausage digit' inflammation of the entire digital unit. When asked whether dactylitis is bilateral or unilateral, Armstrong says it's often oligoarticular, involving only a few digits, and clinicians shouldn't be surprised to see it unilaterally, though more severe disease can present bilaterally.
Her targeted labs include CRP and ESR, which are more suggestive of inflammatory arthritis when elevated but don't rule out PSA when negative. Because rheumatoid arthritis is also common in psoriasis patients, she checks rheumatoid factor and anti-CCP — a positive result on either points more toward RA. She may also order initial imaging to jump-start the workup while patients wait for rheumatology.
Diagnosis, Referral, and the Cost of Delay
When a patient presents with fairly classic PSA — good evidence of inflammatory arthritis, suggestive labs, and fulfillment of the CASPER classification criteria — Armstrong will make and document the diagnosis herself. But she still refers to rheumatology for confirmation, since certain arthritities can mimic PSA. She notes the diagnostic challenge runs both ways: dermatologists also get referrals from rheumatology asking whether a rash is psoriasis.
Delay carries real consequences. Armstrong points out that even a six-month delay can show radiographic progression, and unlike psoriatic skin, which typically heals without scarring, the bone changes in PSA — erosions and joint space narrowing — are progressive and irreversible. That reality reframes the urgency: dermatology clinicians shouldn't simply wait months for a rheumatology slot.
She also broadens the risk picture. Compared with psoriasis patients without arthritis, PSA patients may carry an even higher magnitude of cardiovascular comorbidity, including MI and stroke risk. Add functional impairment, reduced work productivity, depression, and fatigue — the last now formally measured in some studies — and the case for early recognition becomes clear. PSA tends to track later than psoriasis and is predominantly an adult disease, though it can affect pediatric patients at lower absolute rates.
Treating With Confidence Before Rheumatology
Armstrong's key treatment principle: regardless of the degree of skin involvement — even just 1% — if she suspects PSA, she starts a systemic therapy directed at the joints as well as the skin. Fortunately, most systemic psoriasis therapies carry a PSA indication, so clinicians can protect the joints while patients await rheumatology evaluation.
She frames her choices around the GRPPA recommendations (Group for Research and Assessment of Psoriasis and Psoriatic Arthritis), which break PSA into domains — peripheral arthritis, dactylitis, enthesitis, and skin and nail — each with listed therapies. For patients preferring oral options, apremilast and deucravacitinib are both indicated. With no head-to-head data against biologics, Armstrong notes that clinical experience suggests joint efficacy may be a bit more modest with orals.
For very active, severe disease, she leans toward biologics, noting that the IL-17 and IL-23 classes work well in both the skin and joints, with data now showing inhibition of radiographic progression. Her closing pearl for APPs: many of these advanced therapies originated in dermatology, so dermatology clinicians are often more familiar with them than rheumatology colleagues — which means treating both skin and joints can deliver tremendous benefit, especially where rheumatology access is limited.