Multisystem inflammatory syndrome

COVID-19: Multisystem inflammatory syndrome in children (MIS-C)

Let’s start with the good news – COVID-19 in children is usually asymptomatic to mild disease.

Severe cases are very rare and usually affects children with underlying chronic health problems.

But we discovered that it can cause a rare complication 2-6 weeks after either symptomatic or asymptomatic COVID-19 infection. This is this multisystem inflammatory syndrome (MIS-C) in children, sometimes also called Pediatric multisystem inflammatory syndrome (PIMS). It was describes in all age roups under 18 years and rarely even in adults, but the median age is around 9.

What is MIS-C or PIMS?

This syndrome is what we call an “inflammatory” syndrome. For a reason we don’t really know why and how, COVID-19 infection causes an exaggerated delayed immune system response which causes damage to different organs in the body.

Is it a new disease?

Well, since COVID-19 is new than this rare complication is also new and has its unique characteristics. But, the concept of an exaggerated immune system response after viral infections/other triggers in not new to us. MIS-C/PIMS share some features with other “inflammatory syndromes” such as Kawasaki disease, Hemophagocytic lymphohistiocytosis, Macrophage activating syndrome, Toxic-shock syndrome etc.

Is it a common complication of COVID-19 in children?

No (remember the good news). It is very rare and occurring in <1% of children with confirmed COVID-19 infection, with Afro-Americans and Hispanic children affected more than Asian.

What are the signs and symptoms of MIS-C / PIMS?

Because the basis for this syndrome is damage to different organs from an exaggerated uncontrolled immune response, it causes signs and symptoms in many different organs. You have to remember that it has a spectrum of severity from mild to severe illness, but the classic presenting sign and symptoms includes (sometimes only some of those):
• Persistent fever
• Gastrointestinal – abdominal pain (even mimicking appendicitis), vomiting, diarrhea
• Cardiovascular – the heart is involved causing a drop in blood pressure and need for infusing drugs to stabilize its function
• Neurological – headache, sleepiness and confusion
• Rash
• Red swollen lips, “strawberry” tongue
• Red eyes
• Lab test demonstrating elevated “inflammatory markers” (proteins in our blood that rise up in cases of inflammation in our body), elevated cardiac markers indicating damage to the heart, evidence of damage to the kidneys and the liver, abnormal coagulation studies (proteins involved in the process of bleeding and clot formation) and abnormal blood cell counts
• Less prominent respiratory symptoms in contrast to the classic COVID-19 symptoms

What are the treatment options for MIS-C / PIMS?

The first and most important step is to suspect and diagnose this complication as soon as possible. It is also important to be hospitalized in a medical center familiar with and who have treated other cases of this severe disease.
Now, if the immune system is causing all of this than the main strategy of the treatment are drugs that suppress the exaggerated and uncontrolled immune response. These include high-dose steroids, Intravenous immunoglobulins (IVIG) and inhibitors of proteins involved in activating immune system cells (IL-1 and IL-6 inhibitors). These agents are usually combined with low dose aspirin for its anti-inflammatory effect and anti-platelet effect and intensive care supporting care to stabilize blood pressure and heart function.

What are the outcomes of MIS-C / PIMS?

This is a new clinical syndrome so there are no long-term follow up studies. Remember good news? Although this syndrome can be very severe and sometimes require intensive care treatment, most of the children recover with a very low mortality rate (<2%). Also, most of the children have a complete recovery of their heart function, regression of coronary aneurysms and no arrythmias. There are on-going studies investigating what are the long-term consequences of this syndrome.

In conclusion, if your child had COVID-19 infection during the last 2-6 weeks (symptomatic or discovered by screening) and suffers from fever and one of the symptoms and signs above – it is advised that you seek medical care. In most of the cases your physician will diagnose other, more routine children’s diseases. However, if this post can get even one child to be recognized, diagnosed and treated earlier, then it did its job.

So even though this mysterious syndrome is severe and disturbing I think we should take the good news:
COVID-19 is usually very mild in children.
This MIS-C/PIMS is very rare among children infected with COVID-19.
This concept of “inflammatory syndrome” is not new to us.
We have good treatments for this syndrome – we must recognize, diagnose and treat those children early so keep this complication in mind.
Most of the children get out of this scary roller coaster uneventfully.

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