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Kawasaki shock syndrome in monozygotic twins

Twelve-month-old, previously healthy, fully immunised monozygotic twins of Nepalese descent presented to their general practitioner with fever and coryza when cases of COVID-19 had been confirmed in their community. No diagnostic testing was performed. Both were prescribed amoxicillin for bilateral otitis media and nystatin for oral thrush. Reportedly, the twins made a full recovery before developing a new illness 3 weeks after their initial illness. They presented to their local hospital emergency department with a 2-day history of fever, cough and rhinorrhoea. On examination, they had maculopapular rash, generalised oedema and no features of shock. They were treated empirically with ceftriaxone and rehydrated. Both twins’ respiratory viral polymerase chain reactions (PCRs), including SARS-CoV-2, were negative. Twin-A had normal blood cultures, chest X-ray and lumbar puncture. On day 4 of illness (DOI-4), twin A developed melaena and hypovolemic shock which were corrected with rehydration. Decreased responsiveness raised the possibility of encephalopathy. He exhibited three criteria of Kawasaki disease (KD) on the fifth day of fever: excoriation of lips and scrotum, maculopapular rash and oedema of hands and feet. Lymphadenopathy was not found but stridor and hyperextended neck posturing suggested deep tissue inflammation of the neck. Supplementary findings supporting a diagnosis of KD included C-reactive protein 78, white cell count (13.9), lymphopenia (1.0), anaemia (haemoglobin 84), hypoalbuminaemia (22), transaminitis (aspartate transaminase 69) and radiological evidence of gall-bladder hydrops. Meanwhile, on DOI-5, twin B’s illness mirrored that of his brother. Not only did they both have hypovolaemic shock, lethargy, oral desquamation and generalised oedema, but also the same signs of deep tissue inflammation in the neck. This neck swelling would lead to hypoxic upper airway obstruction, necessitating intubation and ventilation on DOI-6 for twin B. This intervention was challenging given the swelling of impinging deep tissues and sloughing of pharyngeal mucosa. Additional investigations for this twin included C-reactive protein 163 and white cell count 18.1, while cerebral spinal fluid (CSF) microscopy, culture and respiratory PCR tests were unremarkable. His urine culture revealed sterile pyuria, although the sample was obtained after the initiation of antibiotic therapy. These monozygotic twins concurrently met the American Heart Association diagnostic criteria for incomplete KD, with additional hypovolaemic shock: Kawasaki shock syndrome (KSS). Neither had evidence of cardiac disease or dysfunction as both had normal echocardiography at presentation as well as at 6-week follow-up. Neither required inotropic support during their illnesses. Both were treated with aspirin and intravenous immunoglobulin (IVIg) on DOI-5 and 6, respectively. For twin A, tachycardia, fever and stridor resolved within 36 h of IVIg treatment. However, twin B required a second dose of IVIg and had a more turbulent course. He was extubated after 3 days (DOI-9). Ongoing lethargy prompted fundoscopy and magnetic resonance imaging of the brain which were normal. Magnetic resonance imaging angiography was not performed. Unresolved neck swelling and swallow dysfunction would epitomise twin B’s recovery. Even at 2 weeks following extubation, he required thickened fluids to avoid aspiration during swallowing as demonstrated on a video fluoroscopic swallowing study. Subsequently, twin B represented with fevers 4 weeks after discharge and had lung consolidation and a lung abscess. He was treated empirically as if for aspiration pneumonia; no pathogen was identified. COVID-19 serology was negative for both twins (post IVIg) and for one parent. The other parent’s initial COVID-19 serology was equivocal and on repeat testing was negative. Twin B also had bronchial lavage samples which were negative for COVID19 PCR. Key Points 1 Kawasaki Shock Syndrome (KSS) is a rare form of Kawasaki Disease (KD) which presents as hypovolaemic shock early in the course of illness and like KD can present concurrently amongst monozygotic twins. 2 Soft tissue swelling of the paraand/or retropharangeal spaces is a reported feature in 0.6% of cases of KD. This swelling plus the pharyngeal mucositis typical of this disease can lead to complications of intubation and ventilation. 3 Our understanding of paediatric multi-system inflammatory syndrome (PIMS) and how it relates to KD is a rapidly evolving topic.