What Are the Five Types of Psoriatic Arthritis?

Psoriatic arthritis is a type of inflammatory arthritis. It is different from other types of arthritis because it affects the joints differently and also involves the skin. The main types of psoriatic arthritis include symmetric polyarthritis, asymmetric oligoarthritis (asymmetric psoriatic arthritis), distal arthritis, arthritis mutilans, and spondyloarthritis.

People with psoriasis, a chronic autoimmune skin condition that causes rapid skin cell growth and renewal, can develop psoriatic arthritis, a type of inflammatory arthritis. Psoriatic arthritis is not the same as other forms of arthritis because it involves the skin and it affects the joints differently. 

There are five main types of psoriatic arthritis (PsA), classified by the types of joints that are affected. Patients may have one or more types. 

• Symmetric polyarthritis
  • Affects five or more joints on both sides of the body (symmetric), similar to the symptoms of rheumatoid arthritis
  • The most common type of psoriatic arthritis, and accounts for about half of all cases
• Asymmetric oligoarthritis (also called asymmetric psoriatic arthritis)
  • Usually affects fewer than five small or large joints in the body
  • Joint symptoms only occur on one side of the body (asymmetrical)
  • Accounts for about 35% of PsA cases
• Distal arthritis
  • Affects end joints of the fingers and toes (the distal interphalangeal joints)
  • May cause nail changes such as spotting, pitting, or separating from the nail bed
  • Fewer than 20% of patients with PsA have distal arthritis alone; it tends to occur with other types of psoriatic arthritis
• Arthritis mutilans
  • A severe type of psoriatic arthritis that can deform and destroy the joints in the fingers, hands, wrists, and feet
  • This type prevents bone cells from breaking down and rebuilding, which can cause fingers to look like the opening of opera glasses (“opera glass hand”) or like a telescope (“telescoping finger”)
  • Other symptoms include stretched, shiny, and wrinkled finger skin; stiffness and immobility of the joint due to fused together bones (ankylosis); and wearing down of joints and bone tissues in the feet and hands
  • Arthritis mutilans is rare, and fewer than 5% of patients with PsA have this type
• Spondyloarthritis
  • Psoriatic arthritis is a type of spondyloarthritis, which refers to several different types of arthritis share some characteristics
  • Symptoms of spondyloarthritis include inflammation in the joints of the spine, which can cause pain and stiffness in the neck, lower back, and sacroiliac joints (on each side of the spine
  • If not treated, the bones in the spine (vertebrae) may fuse together
  • Extremities and hips may also be affected