Multisystem inflammatory syndrome in adults in Hong Kong: two case reports

A 51-year-old Chinese woman presented to Pamela Youde Nethersole Eastern Hospital on 29 September 2022 with a 1-week history of intermittent fever and confusion.She enjoyed good past health and had received three doses of Comirnaty vaccine with the last dose administered on 18 February 2022.She was first symptomatic and with a positive rapid antigen test for coronavirus disease 2019 (COVID-19) on 2 September 2022.She recovered after 8 days without the need for antiviral therapy.Respiratory samples over the initial 4 days of admission were negative for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) polymerase chain reaction (PCR).Magnetic resonance imaging of the brain on 30 September 2022 revealed focal cytotoxic oedema in the splenium of the corpus callosum, possibly indicative of encephalitis or encephalopathy (Fig a).Chest X-ray on admission revealed diffuse right lung opacities (Fig b).The chest symptoms of the patient deteriorated with bilateral involvement and increased need for oxygen support, and she was transferred to the intensive care unit with use of a high-flow nasal cannula.She was intubated on 2 October 2022 as oxygenation was suboptimal.Lumbar puncture was unremarkable.Chest X-ray on 5 October 2022 showed dense bilateral opacities (Fig c ), and computed tomography of the thorax on 5 October 2022 showed bilateral pulmonary consolidations and diffuse ground glass opacities.She also developed anaemia (haemoglobin level: 7.9 g/dL) and thrombocytopenia (platelet count: 78 × 10 9 /L).She was in a hyperinflammatory state with ferritin level of 14057 pmol/L, C-reactive protein level of 273 mg/L, lactate dehydrogenase level of 1081 IU/L, and persistently elevated D-dimer level of >8000 ng/mL.Immunoglobulin G antibody level against SARS-CoV-2 receptor-binding domain on 3 October 2022 was 34 225.34AU/mL.The patient was otherwise haemodynamically stable.Electrocardiogram showed sinus rhythm and highsensitivity troponin I level was only mildly elevated