Psoriatic arthritis (PsA) mutilans is a rare and severe type of PsA. The condition ultimately causes bone loss in the affected joints, which can make it impossible to bend or straighten them.

PsA mutilans is the most severe form of PsA. It causes joint damage and the destruction of bone tissue. This arthritis subtype is sometimes called “opera glass hand” or “telescopic finger.”

PsA mutilans typically occurs in the hands and sometimes affects the fingers, wrists, and feet. It’s considered rare.

Keep reading to learn what symptoms to look out for, what causes this condition, and more.

As of 2020, psoriasis affects at least 7.55 million people living in the United States. It’s one of the most common autoimmune diseases in the United States. According to the National Psoriasis Foundation (NPF), about 30% of people with psoriasis develop PsA.

Of the people with PsA, research indicates that roughly 2–20% develop PsA mutilans.

There are five types of PsA, and PsA mutilans is considered the most severe. To understand how the condition develops, it’s helpful to understand how PsA occurs.

You usually develop PsA if you’ve already had psoriasis. Psoriasis is caused by an autoimmune response in your body, where your immune system attacks your healthy cells. This can cause inflammation throughout the body, including the joints. It’s the main cause of arthritis.

Long-term joint inflammation can cause permanent damage. Certain bones, like those connected to frequently used joints, may severely erode and dissolve. When this happens, it’s known as PsA mutilans.

PsA mutilans can be caused or triggered by:

  • physical joint trauma in people with PsA
  • other environmental triggers
  • genetics, which may play a role in the development of PsA

People can develop bone loss in one or more joints.

PsA mutilans is a severe subtype of PsA. People who develop PsA may experience the following symptoms:

  • stiff joints
  • joint pain
  • decreased range of motion
  • swelling
  • skin rash
  • nail deformity

If you develop PsA mutilans, the bone in the affected joints will begin to disappear. This can result in symptoms that may include:

  • inability to straighten or bend the affected joint
  • shortened joints
  • loose skin in affected joints

Over time, as the affected joints shorten, loose skin may develop in the affected areas.

PsA mutilans is rare, so there’s little evidence on how to predict whether it will develop.

So far, research into the PsA risk factors is inconclusive. Childhood obesity and diagnosis of psoriasis at a young age may be risk factors. However, the only strong indicator of developing PsA is a family history of the condition.

Potential risk factors for PsA can include:

  • genetics
  • family history
  • history of infection requiring antibiotics
  • skin trauma
  • joint trauma

According to the NPF, 30% of people with psoriasis develop PsA. However, the diagnosis may not always occur in that order, and some people with PsA do not develop psoriasis.

To diagnose PsA mutilans, a doctor will first confirm that you have arthritis. After checking your joints for signs of swelling or tenderness, they’ll likely request diagnostic testing.

The doctor may order lab tests to check for inflammation. They will also likely recommend an X-ray or other imaging test to assess joint damage.

Once the doctor has diagnosed you with arthritis, they’ll request testing a blood sample to determine the type of arthritis you have. For example, if rheumatoid factor (RF) and cyclic citrullinated peptide (CCP) antibodies are in your blood, you may have rheumatoid arthritis (RA).

Currently, there isn’t a lab biomarker for PsA or the PsA mutilans subset. PsA mutilans is diagnosed by checking the severity of bone damage. There are very few conditions associated with such severe bone loss.

People with this condition may have certain features that can include:

  • telescoping of one bone into another
  • shortened digits
  • pencil-in-cup deformity, where the bone appears sharp on an X-ray and the connecting bone has a cup shape
  • osteolysis, a condition in which bone tissue degrades and becomes softer
  • other nearby joints may be affected, such as the small joints of the hands

PsA mutilans is a progressive disease. The sooner it’s diagnosed, the higher the chance there is to have a greater impact on slowing disease progression. Treatment goals can include managing your symptoms and helping maintain or improve your quality of life.

Treatment options can vary depending on disease progression, co-occurring conditions, and the parts of the body affected.

Treatment options can include:

Many treatments include the DMARD methotrexate (Trexall), a TNF inhibitor, or both.

Methotrexate may ease your arthritis symptoms. But it’s unclear whether it can slow disease progression.

TNF is a protein in the body responsible for inflammation. According to the American College of Rheumatology, TNF inhibitors can help reduce inflammation and keep the disease from getting worse. Suppressing inflammation keeps joints from feeling stiff or painful. Reducing inflammation may also help restore joint function.

A 2017 research review suggests that switching between anti-TNF medications in the event that one becomes less effective may be an effective treatment strategy.

People with PsA mutilans usually live a reduced life span because this type of arthritis can cause permanent disability if it’s not treated. There isn’t much research on the outlook because it’s such a rare form of PsA.

We do know that when left untreated, PsA can damage bone. As bone is destroyed, the fingers and toes may shorten and change shape, leading to decreased joint function.

However, a diagnosis of PsA mutilans means something different today than in the past when it was called “opera glass hand.”

Your outlook can improve dramatically when PsA is diagnosed and treated as soon as possible. Early treatment can help prevent bone loss.

Bone tissue cannot be fully restored. However, treating your PsA can help slow bone damage. Treatment plays an important part in helping prolong the use and functionality of affected joints.

Diseases that are difficult to predict can be difficult to prevent. This describes PsA. Currently, the condition is not preventable.

However, detecting PsA early and getting treatment can help prevent and slow bone damage.

If you have a family history of psoriasis — or experience arthritis symptoms, especially if you have psoriasis — talk with a doctor.

PsA mutilans is a severe subtype of PsA. It leads to bone damage and loss. It can also cause joint stiffness and a loss of mobility.

If you experience symptoms of PsA, it is important to get medical attention. Early detection and treatment can help preserve joint function.