Your Guide to Pediatric Granulomatous Arthritis (PGA)

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The question “What’s in a name?” can be particularly difficult to answer when it comes to diseases that have or are linked to more than one name. Do these different names matter? What did they tell you?

Pediatric granulomatous arthritis (PGA) is a disease that goes by many names. Three of these names are Blau syndrome (BS), early onset sarcoidosis (EOS), and chronic granulomatous disease (CGD).

Don’t worry if you’ve never heard of BS, EOS or CGD before. You’re not alone! After all, BS is so rare that less than 300 people in the United States are believed to have this condition.

In order to understand PGA, it is essential to understand what the terms ‘BS’, ‘EOS’ and ‘CGD’ mean. So we’ve combed through the scientific research to help you understand these names, how they fit together, and what they mean for PGA diagnosis and treatment.

As its name suggests, PGA is an arthritis that occurs in young people as result of granulomatous inflammation.

BS, EOS, and CGD are chronic genetic disorders that cause granulomatous inflammation in children. So, when arthritis is present as a result of this granulomatous inflammation, it can be called PGA.

The path to PGA can begin with a genetic mutation. The mutation and its resulting effects are called BS or EOS. BS and EOS are chronic progressive diseases.

BS and EOS are essentially identical conditions because they have the same genetic cause and the same symptoms. Both include NOD2 gene mutations and usually manifests as granulomatous dermatitis (inflamed skin), arthritis (joint pain), and uveitis (swelling of the middle layer of the eye).

The difference between these two conditions is that EOS is caused by new genetic modifications. It occurs in people with no history of disorder in their family. On the other hand, BS is a hereditary condition which comes with a family history of genetic mutation.

For a person to be included in international register of these conditions, they must have granulomatous inflammation, arthritis, and uveitis or eye rash.

Like BS and EOS, CGD is a disorder in which people can develop granulomas.

CGD is a rare inherited disorder of the immune system that does not allow phagocytic leukocytes – a type of white blood cells that help prevent infection – to kill germs. This means that people with CGD are not protected against bacterial and fungal infections.

Children with CGD are usually born healthy but develop serious infections during infancy and early childhood. These infections can affect the lungs, skin, liver, lymph nodes and intestines.

People with CGD may also develop granulomas, which are masses of inflammatory material. These frequently develop in the skin, gastrointestinal tract, and genitourinary tract. (GCD was named for these granulomas before the genetic part of the disease was discovered.)

Most children with CGD will be diagnosed by age 5. Symptoms leading to this diagnosis may include:

  • fevers
  • rashes, which can appear as early as 1 month of age and usually appear on the face before spreading to the trunk
  • joint pain, which may be accompanied by areas of swelling resembling cysts on the backs of the feet and wrists
  • arthritis
  • pneumonia
  • bacterial and fungal infections

After reviewing a person’s medical history and performing a physical exam, healthcare professionals diagnose frequently CGD by skin biopsy and a variety of tests.

These may include:

  • neutrophil function tests to determine how well white blood cells are working
  • a dihydroergotamine reduction test
  • genetic tests to confirm the specific genetic mutation

It is also important to rule out chronic infections before diagnosing someone with CGD.

The only way for a medical professional to diagnose BS or EOS without asking questions is to do a genetic test for the specific NOD2 gene mutation.

Treat APG requires a multidisciplinary approach.

Healthcare professionals often prescribe steroids to help manage arthritis pain and inflammation. However, prolonged use of these drugs can cause unwanted side effects.

To suppress disease activity and allow these treatments to be tapered off, a healthcare professional may prescribe the immunosuppressive drug methotrexate.

There has been a lack of evidence-based treatment options, but healthcare professionals are beginning to use anti-TNF monoclonal antibody agents in PGA treatment. Given that tumor necrosis factor (TNF)-alpha plays a possible role in the inflammatory conditions of CGD, etanercept (an anti-TNF agent) could be a game-changer in future treatment plans.

PGA is a rare disease that causes arthritis pain in very young children as a result of granulomatous inflammation. Genetic disorders cause PGA. Most people with PGA appear healthy at birth, but begin to suffer from frequent skin conditions and illnesses soon after birth.

PGA is very rare. If you think your child may have PGA, the next step is to contact a medical professional for help and referrals.

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