Psoriatic Arthritis: Statement Analysis
Statements (a) and (e) are correct. Enthesitis and dactylitis are indeed characteristic manifestations of psoriatic arthritis, and joint involvement can present as symmetric polyarthritis resembling rheumatoid arthritis 1.
Detailed Analysis of Each Statement
a) Characteristic manifestations are enthesitis and dactylitis - CORRECT
This is definitively true. Enthesitis (inflammation at tendon/ligament insertion sites) and dactylitis ("sausage digit") are hallmark features that distinguish PsA from other inflammatory arthritides 1.
- Enthesitis commonly affects the plantar fascia insertion, Achilles tendons, and ligamentous attachments to ribs, spine, and pelvis
- Dactylitis represents a combination of enthesitis of tendons/ligaments plus synovitis involving an entire digit
- These features are so characteristic that dactylitis is specifically included in the CASPAR diagnostic criteria 1
b) Serum rheumatoid factor (+) - INCORRECT
Rheumatoid factor negativity is a defining feature of PsA. The CASPAR criteria explicitly include "rheumatoid factor negativity" as one of the diagnostic features 1. PsA is classified as a seronegative spondyloarthropathy. Patients displaying high titers of rheumatoid factor should not be given the diagnosis of PsA 1.
c) The patient always suffers from cutaneous psoriasis - INCORRECT
Skin lesions do NOT always precede or accompany arthritis. While 84% of PsA patients had cutaneous manifestations before arthritis onset (average 12 years prior) 1, the temporal relationship varies significantly:
- Skin precedes arthritis in 64.5-72.7% of cases 2
- Arthritis precedes skin in 14.9-19.4% of cases 2
- Both develop simultaneously in 16.1% of cases 2
The CASPAR criteria accommodate this by allowing diagnosis based on personal history or family history of psoriasis, not requiring current skin disease 1.
d) The sacroiliac joints are not affected - INCORRECT
Sacroiliac involvement is well-documented in PsA. Approximately 20-50% of patients have involvement of both spine and peripheral joints 1. The Moll and Wright classification specifically includes "spondylitis predominant" as one of five PsA subtypes 1. Sacroiliitis in PsA is often asymmetric and may be asymptomatic, requiring imaging for detection 1.
e) Joint involvement can be symmetrical, resembling rheumatoid arthritis - CORRECT
Symmetric polyarthritis is a recognized PsA pattern. The Moll and Wright criteria explicitly list "polyarticular, symmetric arthritis (rheumatoid arthritis-like)" as one of five PsA subtypes 1. Approximately 20% of PsA patients, especially females, present with symmetric polyarticular inflammatory arthritis resembling RA 1.
Key differentiating features from RA include:
- Absence of rheumatoid factor
- Presence of psoriatic plaques or nail changes
- Less tender/swollen joints than RA
- Presence of dactylitis, enthesitis, and DIP involvement (uncommon in RA) 1
Clinical Implications
When evaluating patients with psoriasis, actively screen for PsA at each visit by asking about:
- Early morning stiffness lasting >30 minutes 3
- Joint pain, swelling, or tenderness
- "Sausage digits" (dactylitis)
- Heel or foot pain (enthesitis)
Early diagnosis and treatment initiation are critical to prevent irreversible joint damage, which can occur in 40-60% of patients and may progress within the first year 1, 3.