Type IV appendiceal intussusception with mucocele and acute appendicitis: a rare case and diagnostic challenge.

Appendiceal intussusception is an exceedingly rare condition where a segment of the appendix invaginates into itself or the cecum. We present a case of a 22-year-old female without significant medical history who presented to the emergency room with acute abdominal pain, nausea, vomiting, and fever for 7 hours. Clinical examination revealed diffuse abdominal tenderness and guarding, with stable vitals. Laboratory results showed leukocytosis and elevated C-reactive protein. Abdominal ultrasound and a limited non-contrast computed tomography scan, suggested ileocecal intussusception, but the appendix was not visualized, indicating it as the leading point. Intraoperatively, an inflamed appendix with mucocele and a Type IV intussusception, where the appendix telescoped into itself and the cecum, was found. Manual reduction, appendectomy, and partial cecectomy were performed. Histopathology confirmed severe appendiceal inflammation but no malignancy. This case highlights the diagnostic challenges and rarity of Type IV appendiceal intussusception, emphasizing the importance of surgical exploration in complex presentations.