Psoriatic Arthritis
psoriatic arthritis
- Common/classic features:
Pencil-in-cup deformity
- The show the pencil-in-cup sign, which occurs through periarticular erosion and bone resorption.
- This finding occurs in many different arthropathies but is especially common in the DIP joint in psoriatic arthritis
Dactylitis (sausage digit)
- Dactylitis of the 3rd and 4th digits – inflammation and swelling of these toes: the most common site of dactylitis in psoriatic arthritis.
Nail dystrophy
- Psoriatic nail dystrophy involves onycholysis (nail detachment), vertical ridges, pitting, and hyperkeratosis.
Additional Features
- Plaque psoriasis – psoriatic arthritis is a manifestation of the skin disease psoriasis: it affects up to one-third of patients with psoriasis and tends to develop several years after the onset of skin lesions.
- Axial spondyloarthritis – it's a less prominent feature of psoriatic arthritis than ankylosing spondylitis but still an important one.
- Enthesitis, which refers to tendon/ligament inflammation (especially of the achilles).
Genetic predisposition
- Note that psoriatic arthritis is considered a polygenic disorder with numerous HLA associations, including: HLA-Cw6, HLA-B38, HLA-B39, in addition to HLA-B27.