Histiocytic Necrotizing Lymphadenitis Mimicking Acute Appendicitis in a Child: A Case Report

Case Report: Acute abdomen and large mesenteric mass as another face of multisystem inflammatory syndrome in an adolescent child: measure twice, act once!

Introduction

During the Covid-19 era, acute abdomen and mesenteric lymphadenopathy were encountered as frequent mimic of appendicitis. This phenomenon can further complicate the diagnosis of acute abdominal conditions, not solely due to bacterial or viral intestinal infections but also attributable to post-infectious acute inflammatory states resulting in either undertreatment of inflammatory conditions or unnecessary surgery.

Case presentation

In this case study, we present the case of an 11-year-old female who initially presented with fever and right lower quadrant abdominal pain, raising concerns of appendicitis. However, upon further investigation, it was revealed that she harbored a sizable mesenteric mass. Subsequent biopsy results unveiled a significant necrotic mesenteric lymphadenitis. Notably, this patient fulfilled the criteria for Multisystem Inflammatory Syndrome in Children (MIS-C), a condition that manifested following persistent postoperative fever. Remarkably, the patient exhibited a highly favorable response to the treatment administered. This clinical scenario presents an atypical manifestation of MIS-C, as the patient displayed a substantial mesenteric mass alongside symptoms mimicking appendicitis, within the context of an acute abdomen.

Conclusion

Clinicians should consider MIS-C and other post-infectious inflammatory conditions in mind when diagnosing acute abdominal cases. The presented case underscores the importance of recognizing atypical presentations of MIS-C that can mimic appendicitis, sometimes necessitating surgical resection of a large lymph node. We propose diagnostic flow chart to aid in the differentiation of acute bacterial appendicitis from MIS-C.

Paediatric inflammatory multisystem syndrome: temporally associated with SARS-CoV-2 (PIMS-TS) — A mimic of intra-abdominal malignancy

We report the case of a school-aged boy who presented with clinical features suggesting acute appendicitis. However, further imaging which included CT, demonstrated an inflammatory mass involving the transverse colon raising the suspicion of lymphoma. He then developed intestinal obstruction, and in view of the rapid progression of the disease, he was thought to have non-Hodgkin’s lymphoma. He underwent an open excisional biopsy, which revealed a necroinflammatory process and no suggestion of lymphoma or an alternative malignancy or specific diagnosis. His steroid treatment was stopped, and he made a good recovery postoperatively. Positive COVID-19 antibodies, positive response to steroids, results and clinical features were consistent with paediatric inflammatory multisystem syndrome (PIMS-TS), with extensive investigation not offering an alternative diagnosis.

While PIMS-TS is a relatively new entity, we believe that this case highlights the importance of it being considered a differential diagnosis of a child presenting with an inflammatory mass.