Paediatric post-COVID-19 hyperinflammatory syndrome mimicking appendicitis: a case series

Abstract

Introduction: A novel hyperinflammatory syndrome has emerged in the paediatric population: paediatric inflammatory multisystem syndrome - temporally associated with SARS-CoV-2 (PIMS-TS). Up to 50% of patients develop shock with cardiac dysfunction but presentation with acute abdominal pain is common and difficult to distinguish from appendicitis.

Method: Prospective case series of PIMS-TS patients presenting to a single UK tertiary paediatric centre.

Results: As of 16 September 2020, 89 patients have presented with PIMS-TS to our institution; 19 (21.3%) were referred for surgical review. Pyrexia and acute abdominal pain were seen in all 19 patients. Diarrhoea was reported in 14 (73%) and vomiting in 12 (63%). On examination, eight (42%) had right abdominal tenderness, of which five had right iliac fossa (RIF) peritonism. C-reactive protein (CRP) was universally raised: median 176 (15-463)mg/l. Abdominal imaging was performed in 17 (89%), with 11 undergoing abdominal ultrasonography (65%) and 8 abdominal computed tomography (47%); two required both. Findings included nonspecific features of inflammation in the RIF. Eight patients (42%) had an abnormal echocardiogram at admission. Two (10%) patients, with classical signs and symptoms of appendicitis, underwent appendicectomy without radiological imaging and were subsequently diagnosed with PIMS-TS. During the same period, 18 patients underwent appendicectomy for histologically confirmed appendicitis. Serum CRP and ferritin levels were significantly higher in the PIMS-TS cohort compared with children with appendicitis.

Conclusions: PIMS-TS is a novel paediatric condition that may mimic appendicitis. It should be considered in patients presenting with abdominal pain to avoid unnecessary surgery in children at risk of cardiovascular instability.

Keywords: Acute appendicitis; COVID-19; Hyperinflammatory syndrome.

Figure 1

High-frequency US in a 9-year-old male with sepsis, abdominal pain, vomiting and diarrhoea demonstrated numerous mildly enlarged lymph nodes (more than three nodes measuring >8mm in short-axis diameter) in the RIF (arrows) with increased echogenicity of the surrounding mesenteric fat (*) in keeping with inflammatory change. The appendix was not visualised. RIF = Right Iliac Fossa; US = Ultrasound Scan.

Figure 2

CT abdomen in a 14-year-old male with sepsis: marked caecal wall thickening (thin arrow) surrounded by mesenteric hazy fat-stranding (thick arrows). There was also a small amount of free fluid and local lymphadenopathy (not shown here). The appendix could not be identified due to the marked inflammatory change. CT = Computed Tomography.

Figure 3

CT abdomen in a 12-year-old male with fever, abdominal pain, raised WCC and CRP shows a small amount of free fluid (thick arrow) in the RIF and pelvis. An appendicolith was noted (thin arrow); however, the appendix appeared normal and there was no surrounding inflammatory change. CRP = C-Reactive Protein; CT = Computed Tomography; RIF = Right Iliac Fossa; WCC = White Cell Count.

Figure 4

Comparison between serological markers in PIMS-TS patients compared with those with acute appendicitis. Data presented as median (IQR). *Clinically significant p value (<0.05). IQR = Interquartile Range; PIMS-TS = Paediatric Inflammatory Multisystem Syndrome – Temporally Associated with SARS-CoV-2.