Paediatric Inflammatory Multisystem Syndrome (PIMS) is a serious but rare health condition affecting children and adolescents. It typically appears several weeks after a primary infection and is characterized by widespread inflammation affecting multiple organs. Although PIMS can lead to severe illness requiring immediate medical attention, most children recover completely with timely treatment. Understanding the syndrome’s nature, symptoms, and management helps parents and caregivers recognize when to seek help.
Defining PIMS and Its Post-Infectious Nature
PIMS is a hyperinflammatory state, characterized by an exaggerated and uncontrolled immune response rather than an active infection. It is often referred to interchangeably with Multisystem Inflammatory Syndrome in Children (MIS-C) by various health organizations. PIMS represents a delayed reaction, typically manifesting two to six weeks after the child has recovered from the initial illness.
The primary trigger identified for PIMS is exposure to the SARS-CoV-2 virus, which causes COVID-19. Most children who develop PIMS had either very mild or entirely asymptomatic initial infections. Laboratory findings support the syndrome’s post-infectious timing, frequently showing the presence of antibodies to the virus but a negative result for active viral particles.
This mechanism suggests that the body’s immune system becomes dysregulated after fighting the initial virus, mistakenly attacking healthy tissues throughout the body. This immune overdrive results in systemic inflammation that can impact various organs. PIMS is distinct from the acute phase of the viral infection, as it is the body’s delayed response causing subsequent damage.
Recognizing the Key Signs and Symptoms
The presentation of PIMS is complex because it involves multiple body systems, meaning not every child exhibits the same set of signs. A hallmark of the syndrome is a persistent high fever, defined as a temperature above 38.0°C that lasts for 24 hours or more. This prolonged fever is a consistent indicator of the condition.
Many patients experience prominent gastrointestinal issues, including severe abdominal pain, vomiting, and diarrhea. These symptoms often precede more generalized issues and can be mistaken for other common childhood illnesses. Signs affecting the skin and mucous membranes are also common, such as a widespread rash or conjunctivitis where the eyes appear red.
The syndrome can also present with mucocutaneous findings similar to other inflammatory conditions, including cracked, red lips, a swollen tongue, and swollen hands and feet. More serious signs relate to the potential for shock, which occurs when the body’s circulation is compromised. Parents should seek immediate medical help if a child shows signs such as:
- Trouble breathing
- Persistent chest pain
- Confusion
- Skin that appears blotchy, pale, or bluish
Clinical Management: Diagnosis and Treatment Protocols
Diagnosing PIMS involves clinical observation, recent infection history, and specific laboratory tests. Healthcare providers look for a pattern of symptoms along with evidence of recent SARS-CoV-2 infection or exposure. Blood tests detect markers indicating high levels of systemic inflammation, such as elevated C-reactive protein (CRP), ferritin, and D-dimer levels.
To assess the extent of organ involvement, particularly the heart, diagnostic imaging like an echocardiogram is routinely performed. Because PIMS can cause myocardial dysfunction and inflammation of the coronary arteries, the heart’s function is closely monitored. These steps help distinguish PIMS from other conditions that present with similar inflammatory symptoms, such as sepsis or Kawasaki disease.
The standard treatment for PIMS focuses on rapidly reducing the excessive immune response to prevent organ damage. Immunomodulatory agents are the primary treatment, most commonly involving intravenous immunoglobulin (IVIG) and corticosteroids. IVIG, a blood product containing antibodies, helps regulate the immune system.
Corticosteroids, often high-dose methylprednisolone, are also given to suppress widespread inflammation. When the heart is involved, supportive care is provided, including fluid management and sometimes low-dose aspirin to prevent blood clotting if coronary artery changes are detected. For children who do not respond to first-line therapy, other targeted biologic agents may be considered.
Recovery and Long-Term Follow-Up
With prompt diagnosis and treatment, the prognosis for children with PIMS is favorable, and most patients make a full recovery. However, since the syndrome can temporarily affect the heart and other systems, careful monitoring after the acute phase is necessary. Follow-up care is a structured part of the recovery process.
Cardiology monitoring, including repeat echocardiograms, is important to ensure that temporary heart issues, such as coronary artery dilation, resolve completely. While most cardiac abnormalities improve within six months, a small subset of children may require ongoing specialist review. Some children also experience lingering symptoms like fatigue, physical deconditioning, or psychological sequelae requiring multidisciplinary support.