BACKGROUND: Appendiceal duplication is an extremely rare congenital anomaly, with an incidence of 0.004% to 0.009%. An association with an appendiceal mucocele is even rarer. It can complicate the diagnosis and management of right iliac fossa pathology and remains difficult to identify preoperatively. Failure to recognize it can result in recurrent symptoms, missed pathology, intraoperative challenges, and medicolegal consequences. This report describes the case of a 45-year-old woman with history of a loculated peri-appendiceal abscess managed with percutaneous drainage and intravenous antibiotics, subsequently found to have a duplicated appendix with mucocele identified after right hemicolectomy.

CASE REPORT: A 45-year-old woman presented with right lower quadrant abdominal pain and fever that began 2 months ago. Contrast-enhanced computed tomography demonstrated ruptured appendicitis with a loculated peri-appendiceal abscess, successfully managed with percutaneous drainage and intravenous antibiotics, resulting in clinical improvement. She re-presented 2 months later with recurrent abdominal pain. Diagnostic laparoscopy revealed a dilated, firm appendiceal tip and a mass-like ileocecal inflammatory complex, raising suspicion of malignancy. Due to the distorted anatomy and inability to exclude an underlying neoplasm, a right hemicolectomy was performed. Histopathological examination revealed a Type B2 (Cave–Wallbridge) duplication of the appendix, one of which showed mucocele formation and features of resolving appendicitis with no evidence of malignancy.

CONCLUSIONS: Appendiceal duplication is classified according to the Cave–Wallbridge system and is rarely associated with appendiceal mucocele. Diagnosis requires a high index of suspicion and careful intraoperative assessment. Extended resection may be required when anatomy is distorted or malignancy cannot be excluded, to prevent missed pathology and recurrence.

Keywords: Anatomical variation, Appendiceal Diseases, Appendix, Case Reports, Gastroenterology, Mucocele