ISRA May 2022

RLQ Pain and Tenderness in Pediatric Patients with PIMS – Is It Appendicitis? Ask the Sonographer

Anat Ilivitzki 1 Michal Scolnick 1 Luda Glozman 1 Yonathan Butbul 2
1Radiology, Pediatric Radiology Unit, Rambam Health Care Campus, Israel
2Pediatric Rheumatology, Rambam Health Care Campus, Israel

Introduction: Pediatric patients with Pediatric Inflammatory Multisystem Syndrome (PIMS) may present with right lower quadrant pain and tenderness or even peritonitis, resembling the presentation of acute complicated appendicitis. Abdominal sonography is the modality of choice for the primary evaluation in these cases.

Purpose: Our aim in this study was to compare the sonographic findings in pediatric patients presenting with RLQ tenderness or peritonitis due to PIMS versus appendicitis.

Methods: We retrospectively studied all abdominal ultrasound studies performed in our hospital for the evaluation of suspected appendicitis in two groups of pediatric patients, the first with a diagnosis of PIMS and the second with a pathologically confirmed diagnosis of complicated appendicitis. A team of two experienced pediatric radiologists, reviewed and agreed on the pathologic findings.

Results: Altogether we had 17 pediatric patients with PIMS (mean age 8.2y ) and 22 patients with complicated appendicitis (mean age 11y ). The appendix was identified in 20 (91%) patients with appendicitis, all with signs of inflammation, and in 11 (65%) patients in the PIMS group, 8 normal, 3 thickened. Mesenteric lymphadenitis was seen in 8 (36%) of the appendicitis group, all appeared reactive, and in 10 (59%) of the PIMS group, of which 9 (90%) were round, hypoechoic and in clusters; one had central necrosis. Abdominal fluid, unclear to pus, identified in 20 (91%) of the appendicitis patients, mostly peri- appendicular and minimal. In the PIMS group in 7 (41%) there was moderate to large amount of clear ascites. Gall bladder wall thickening was only noted in the PIMS group, in 5 (30%) patients.

Conclusion: RLQ tenderness and abnormal sonographic findings may be seen both in appendicitis and PIMS. Sonographic clues to diagnosis are the appearance of the appendix and the mesenteric lymph nodes along with the amount and consistency of the abdominal fluid.