The Great Imitator Strikes Again: A Case of a Lupus Flare-up Presenting Like an Acute Abdomen.

Description Systemic lupus erythematosus (SLE) is an autoimmune disease affecting all age groups and can manifest in various forms, often making the initial or successive presentations difficult to diagnose. Peritonitis secondary to lupus is a rare manifestation of this disease and the prevalence is said to be much lower in children. We present a case report of an adolescent male with a known history of lupus who presented to the emergency department with a clinical picture consistent with an acute surgical abdomen and underwent an appendectomy. Subsequent workup identified the culprit as a lupus-related peritonitis requiring corticosteroids for resolution.