Kawasaki syndrome, also known as mucocutaneous lymph node syndrome, is an acute inflammatory disease of the small and medium-sized vessels (angiitis) accompanied by high fever.
The cause of the disease is not known, but both infectious and autoimmunological causes are being discussed. Angiitis is responsible for the acute symptoms of the skin and mucous membranes described below, as well as for the resulting complications, the most dangerous of which is damage to the coronary arteries.
In order to diagnose "Kawasaki syndrome", the patient must first have a persistent high fever for at least five days and then fulfil at least four of the following five criteria:
- Eye involvement in the form of non-purulent bilateral conjunctivitis,
- Skin involvement in the form of a rash of different types (polymorphous exanthema),
- Mucosal involvement, which is characterised by typically dry, reddened lips ("lacquer lips") and inflammation of the mucous membranes of the mouth and throat,
- swelling of the lymph nodes in the neck, which can be unilateral or bilateral, and
- reddening of the palms of the hands and feet (palmar or plantar erythema), which after 2-3 weeks progresses to detachment of the skin on the toes and fingertips.
In addition to these external signs, which are important for the diagnosis of Kawasaki syndrome, the internal organs also show signs of systemic vascular inflammation. These are not only collected to complete the findings in a Kawasaki syndrome already diagnosed by the above criteria, but are also used to diagnose a so-called "incomplete" Kawasaki syndrome. Incomplete" Kawasaki syndrome refers to children who do not fulfil the above criteria for "complete" Kawasaki syndrome, but who are likely to have such a syndrome due to the organ involvement listed below:
- Cardiac manifestations: echocardiographic picture of perimyocarditis with effusion formation, new valvular insufficiencies, increased perivascular echogenicity, repolarisation abnormalities on ECG.
- Renal involvement: Proteinuria, leucocyturia or symptoms of urethritis.
- Joint involvement: Arthralgias, arthritides.
- Gastrointestinal involvement: Diarrhoea, abdominal pain
- Hepatic involvement: Increase in transaminases
- Cerebral involvement: Tiredness, fatigue as well as neurological changes up to coma in the sense of encephalitis or meningitis, which is then also accompanied by an increase in cell count and protein in the cerebrospinal fluid.
- Blood count changes: Leukocytosis, thrombocytosis (typically from the 2nd week of illness).
- Non-specific inflammatory markers: significant increase in erythrocyte sedimentation rate, increase in CRP.
If a diagnosis of Kawasaki syndrome is made either by fulfilling the criteria for "complete" Kawasaki syndrome or by determining organ involvement (and in particular cardiac involvement using echocardiography), the patient must receive anti-inflammatory or immunomodulatory therapy, which can stop the inflammatory process and thus prevent progressive damage to the coronary vessels and its consequences (coronary ectasia, coronary aneurysms, coronary thrombosis and corresponding myocardial damage), especially if therapy is started before the 10th day of the disease. This therapy consists of a combination of intravenous immunoglobulin administration, which is intended to end the inflammatory process through an immunomodulatory effect, and acetylsalicylic acid, which also has an anti-inflammatory effect in high doses. Successful therapy is considered to be the removal of fever from the child in the first 36 hours after immunoglobulin administration. If the fever does not disappear consistently after the first dose of immunoglobulin, a second or third dose is necessary. However, the use of high-dose intravenous cortisone is also recommended for the third dose. After the patient has successfully recovered from the fever, acetylsalicylic acid is administered again, but now in a low dose, which is intended to prevent the aggregation of the thrombocytes and thus the formation of blood clots in the coronary vessels. If regular echocardiographic checks show no cardiac involvement, acetylsalicylic acid is finally discontinued after a few weeks. However, if the coronary arteries are found to be dilated, not only is blood-thinning therapy with heparin or, subsequently, Marcoumar necessary, but also further examinations to evaluate the coronary vessel status (cardiac catheterisation).