Psoriatic Arthritis (PsA): Terminology, Features & Diagnosis

Psoriatic arthritis (PsA) is a chronic inflammatory arthritis associated with psoriasis. The formal medical term is psoriatic arthropathy.

Key Features

• Joint involvement: Asymmetric oligoarthritis, symmetric polyarthritis (RA-like), distal interphalangeal (DIP) predominance, spondylitis, arthritis mutilans.
• Enthesitis: Inflammation at tendon/ligament insertions (Achilles, plantar fascia).
• Dactylitis: "Sausage digit" – diffuse swelling of entire finger/toe.
• Skin/nail psoriasis: Plaques, pitting, onycholysis, oil spots.
• Extra-articular: Uveitis, IBD, cardiovascular comorbidity.

Diagnostic Criteria (CASPAR)

≥3 points from: current psoriasis (2), personal/family history (1), nail changes (1), dactylitis (1), negative RF (1), juxta-articular new bone on imaging (1).

Management

• NSAIDs, local glucocorticoid injections.
• Conventional DMARDs: methotrexate, sulfasalazine, leflunomide.
• Biologic DMARDs: TNF inhibitors, IL-17/IL-23 inhibitors, JAK inhibitors.
• Multidisciplinary: rheumatology, dermatology, physical therapy.