The etiology of the disease is multifactorial, with both genetic and environmental factors. PsA affects men and women equally and is predominantly seen in white individuals, similar to psoriasis.
- Pain, stiffness in affected joints, with joint stiffness present for >30 minutes in the morning (after waking) or after prolonged inactivity. Improves with activity (versus osteoarthritis / degenerative joint disease, which typically worsens with activity).
- With axial involvement – Inflammatory back pain and stiffness that improve with activity; night symptoms can cause waking from sleep; decreased range of motion of the axial spine and neck over time.
- Tender / painful; swelling at entheses (sites of tendon insertion into bone).
- Tendonitis / tenosynovitis
- Ocular inflammation may lead to scleral erythema, dry eye / foreign body sensation, or uveitis with potential visual disturbance and pain.
- Tender, painful, swollen joints with possible erythema, effusion, and warmth noted in more actively inflamed joints.
- Dactylitis – Inflammation and swelling of the entire digit including metacarpophalangeal (MCP) through proximal / distal interphalangeal (PIP/DIP) joints and intervening soft tissue, giving a "sausage digit" appearance.
- Enthesitis – Inflammation at tendinous insertion into bone, with tenderness.
- Distal (DIP) arthritis
- Oligoarthritis, asymmetric
- Rheumatoid arthritis (RA)-like symmetrical polyarthritis
- Arthritis mutilans – aggressive, destructive phenotype
- Axial spondylitis, sacroiliitis
- Patients with nail, scalp, and inverse (intertriginous) psoriatic skin disease have a higher risk of developing PsA.
- Several genetic risk markers (HLA associations) are associated with development and variable prognosis in PsA.
- Progression to PsA among patients with psoriasis has been reported to occur at a rate of around 2% per year.
- Episodic flares of the disease in addition to chronic, baseline joint inflammation.
- Joint erosion / damage may accrue over time, with the potential for development of functional impairments.
L40.59 – Other psoriatic arthropathy
33339001 – Psoriasis with arthropathy
- Rheumatoid arthritis (RA) – Symmetric polyarthritis; presentation, clinical course, and radiologic and serologic features are distinct from PsA (may be rheumatoid factor and anti-cyclic citrullinated peptide [anti-CCP] positive). The absence of DIP involvement, asymmetry, axial involvement, dactylitis, skin psoriasis, psoriatic nail disease, and radiography may help distinguish RA from PsA.
- Gout – History of podagra, joint fluid from arthrocentesis demonstrating monosodium urate crystal should help to differentiate; gout and psoriasis / PsA may co-exist, however.
- Pseudogout – Chondrocalcinosis on radiographs and calcium pyrophosphate crystals on joint fluid examination.
- Reactive arthritis – Would not expect the presence of psoriasis skin disease; associated with other symptoms such as preceding genitourinary symptoms, diarrheal illness, and skin findings such as keratoderma blenorrhagicum.
- Ankylosing spondylitis – To be distinguished from axial disease in PsA; PsA tends to have an asymmetric involvement of the sacroiliac joints, formation of "jug-handle" nonmarginal syndesmophytes that are asymmetrically located, skip lesions along the spine (cervical > lumbar involvement).
- Fibromyalgia – Diffuse widespread pain involving "tender point" soft tissue areas. Synovitis is not a component of fibromyalgia. It is important to distinguish enthesitis (inflammation at sites of tendon insertion into bone) from the tender points of fibromyalgia, eg, near the lateral epicondyle of the upper extremity. Fatigue may be common to both conditions. Stiffness may be reported but does not improve with activity.