Psoriatic arthritis
An inflammatory arthritis that occurs in some people with the skin condition psoriasis. It causes painful, swollen and stiff joints — sometimes with swelling of a whole finger or toe, nail changes and back involvement — and, like other inflammatory arthritis, benefits from early treatment.
What it is
Psoriatic arthritis is a chronic inflammatory joint disease that develops in a proportion of people with psoriasis, the immune-driven skin condition that causes scaly plaques. In most people the skin disease comes first, sometimes years earlier, but occasionally the arthritis appears before any obvious rash. It belongs to the spondyloarthritis family and can take several forms: it may affect a few large joints, many small joints resembling rheumatoid arthritis, or the spine and sacroiliac joints with inflammatory back pain. Characteristic features help distinguish it: swelling of an entire finger or toe so it looks like a sausage (dactylitis), inflammation where tendons attach to bone (enthesitis, such as at the heel), nail changes such as pitting and separation, and a tendency to involve the joints at the very ends of the fingers. Fatigue is common, and eye inflammation (uveitis) and inflammatory bowel disease can be associated. Blood tests may show raised inflammatory markers (ESR, CRP), but they are often normal; rheumatoid factor and anti-CCP are usually negative, which helps separate it from rheumatoid arthritis. Diagnosis is clinical, supported by the skin and nail findings and imaging. Left untreated, the inflammation can damage joints, so early recognition and treatment — from anti-inflammatories to disease-modifying and biologic drugs — matter for preserving function.
Key lab markers
- ESR and CRP — inflammatory markers; may be raised in active disease but are often normal.
- Rheumatoid factor — usually negative, helping distinguish it from rheumatoid arthritis.
- Anti-CCP — usually negative, again unlike rheumatoid arthritis.
- Full blood count — may show anemia of chronic inflammation.
- Clinical and imaging findings — the skin, nails and joint pattern, plus X-ray or MRI, are central; blood tests alone cannot confirm it.
Symptoms
- Painful, swollen, stiff joints, often with prolonged morning stiffness
- Swelling of a whole finger or toe (dactylitis, 'sausage digit')
- Pain where tendons attach, such as the heel (enthesitis)
- Nail changes — pitting, ridging, or separation from the nail bed
- Involvement of the joints at the fingertips
- Inflammatory back and buttock pain in some people
- Skin psoriasis (though arthritis can precede it)
- Fatigue
Related symptoms
Related lab panels
When to discuss with a doctor
See a doctor, ideally a rheumatologist, if you have psoriasis and develop persistent joint pain, swelling or stiffness, or if you have swelling of a whole finger or toe, heel pain, or nail changes with joint symptoms even without known psoriasis. Prolonged morning stiffness and joints that improve with movement point to inflammation rather than wear-and-tear. Early diagnosis and treatment help control symptoms and protect the joints from lasting damage. Mediora.AI can highlight raised inflammatory markers and a negative rheumatoid factor and anti-CCP, a pattern that fits psoriatic arthritis rather than rheumatoid arthritis, but these tests are often normal and cannot confirm the diagnosis on their own — the assessment rests on the joint, skin and nail picture, made by your doctor.