One of the complications of COVID-19 is juvenile dermatomyositis (JDM), a connective tissue disease.

In the Children’s Medical Center in Iran, researchers documented that from Feb of 2020 to Feb of 2021, there was an uptake of JDM cases. 8 new pediatric cases were admitted during that time period. The usual for that length of time is much less (typically 2 to 4). Additionally, the average age of the patients admitted this past year was higher than it was typically, and there were more females than males.

Another surge has occurred in Mumbai. However, this surge was in an adult population.

Scholars in this article, propose 3 different hypotheses which may explain this increase.

Hypotheses

1. This increase is true JDM

This hypothesis is justified by the fact that it is well known that infectious agents have the potential to trigger the condition. Other viruses which have been found to trigger JDM include parvovirus B19, influenza, toxoplasma, coxsackievirus B, group A streptococcus, enterovirus, and more. Therefore, COVID-19 could be a trigger for the standard form of the condition.

Further, we know that Type 1 IFN pathway is dysregulated during JDM. Myxovirus resistance protein A is expressed by the body when responding to a viral infection. However, it is expressed in COVID-19 as well.

The deposition of the Myxovirus resistance protein A is one of the first signs of JDM.

2. JDM seen in COVID-19 patients is a prolonged post-viral myositis (PVM)

PVM leads to symptoms typically localized in the soles and gastrocnemius muscles. The symptoms are diffuse/multifocal muscle pain as well as potentially rhabdomyolysis.

The symptoms of this condition start 3-7 days after respiratory symptoms/fever begin. These symptoms tend to resolve after a week, although they can last a full month. However, like many of the symptoms COVID-19 patients experience, this condition could take longer than normal to resolve.

3. JDM seen in COVID-19 patients is a dermatomyositis-like syndrome

This means that the JDM seen in this patient population is not true JDM but a different condition which has the very same symptoms. These scholars explain how it may be another form of hyperinflammation syndrome that we have already seen in COVID-19 patients.

The most frequently documented of these is currently multisystem inflammatory syndrome in pediatric patients, which presents as a Kawaski-like-syndrome. However, JDM-like syndrome could be another form of this hyper inflammation.

The researchers emphasize that this hypothesis only makes sense if the condition seen in COVID-19 patients its less severe in complications and duration than typical dermatomyositis.