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Psoriatic arthritis is a chronic, immune-mediated seronegative spondyloarthropathy associated with psoriasis of skin and nails, characterized by a variable combination of peripheral arthritis, axial disease, enthesitis, and dactylitis.

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https://youtu.be/909OjY851AQ

Epidemiology

Occurs in ~5–30% of patients with psoriasis.
Peak onset: 30–50 years.
Male = Female (axial disease more common in men).
Strong association with HLA-B27 (axial PsA), HLA-Cw6.

Etiopathogenesis

Genetic predisposition: HLA-B27, HLA-Cw6.
Immune dysregulation: IL-17/IL-23 axis, TNF-α pathways.
Environmental triggers: Trauma (Koebner phenomenon), infection.
Pathology: Synovitis + enthesitis → bone erosion + new bone formation.

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Clinical Features

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Mnemonic for features: “P’s of PsA” → Psoriasis, Peripheral arthritis, Pencil-in-cup, Psoriatic nails, Plantar fasciitis (enthesitis).

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Epidemiology

Etiopathogenesis

Clinical Features

Articular Manifestations