What is Psoriatic Arthritis Mutilans?

Psoriatic arthritis mutilans is a rare but severely disabling form of psoriatic arthritis.¹ While there is some debate about the actual clinical definition of arthritis mutilans, there is no doubt that it is the most severe form of psoriatic arthritis.^2,3 It is estimated that anywhere from 1-39% of patients with psoriasis will be diagnosed with psoriatic arthritis.² Of these patients, 2-25% will be diagnosed with arthritis mutilans.¹ Most estimates state that about 5% of psoriatic arthritis patients will be diagnosed with arthritis mutilans, but as the clinical definition of the disease is unclear, the number can vary greatly.² Psoriatic arthritis mutilans seems to affect men and women fairly equally.

What are the symptoms of arthritis mutilans?

Some of the main symptoms of arthritis mutilans are:

• Joint disfiguration, such as telescoping of the fingers, described as “opera-glass hands", or bunching of the toe joints.
• Shortening of the fingers and/or toes due to bone absorption by the body.
• The presence of flail joints, which are joints that cannot stabilize themselves, and cannot function correctly.¹
• Swollen, painful joints due to bone fusion.
• Folds of skin on the fingers created by the shortening of the fingers.³

How is arthritis mutilans diagnosed?

An important tool for diagnosing psoriatic arthritis mutilans is radiographic imaging. When arthritis mutilans patients have X-rays or other images such as MRIs or CTs, these images will show symptoms such as bone resorption, joint erosion, and narrowing of the space in the joints.^1,3 Patients will also have symptoms of bone fusion, as well as bone edema.

What causes arthritis mutilans?

Psoriatic arthritis mutilans seems to be a specific form of psoriatic arthritis that is either a unique disease or a specifically aggressive form of psoriatic arthritis.¹ It is thought to be caused, at least in part, by the immune system attacking itself, or autoimmune disease, like psoriatic arthritis.⁴

What treatments are available for arthritis mutilans?

Treatment for psoriatic arthritis mutilans varies. Patients were traditionally treated with non-steroidal anti-inflammatory drugs (NSAIDs), as well as disease-modifying antirheumatic drugs (DMARD).² These drugs helped reduce inflammation in the affected joints and helped control some of the pain associated with psoriatic arthritis mutilans.

Patients now have the option of using targeted biologic agents, which help control the inflammation by targeting specific cells and pathways in a patient’s immune system.² Biologic and targeted agents are available in oral and injectable forms, making treatment relatively easy for most patients.

It is important to note that early intervention is important in arthritis mutilans as treatment can prevent joint damage and bone destruction. Patients who start biologic agents can regain some function and repair some damage, but therapies need to be started early in order to regain function.²

What is the long-term outlook for arthritis mutilans patients?

With the advent of biologic agents, patients with arthritis mutilans have a better outlook than ever. Biologic agents can slow disease progression and have even been shown to repair arthritis mutilans damage.² Even patients with irreversible damage had clinical benefits from biologic therapies.²

As patients with psoriasis and psoriatic arthritis are now starting to receive biologic therapies such as TNF alpha inhibitors and other biologic agents, there may be even less of an opportunity for psoriatic arthritis to become arthritis mutilans. As new drugs are developed for psoriasis and psoriatic arthritis, hopefully, they will lead to new treatment of existing cases of psoriatic arthritis mutilans, and possible prevention of future cases of this debilitating disease.