Abstract
The differential diagnosis of abdominal pain is wide as both benign and malignant pathologies must be considered. There are currently no published case reports of low-grade appendiceal mucinous neoplasms (LAMNs) mimicking perforated diverticulitis. LAMNs are a heterogenous group of tumours, with no consensus treatment algorithm based on stage and histology. In this case report, we discuss a patient who presented emergently with generalized peritonism, with a diagnosis of perforated diverticulitis made on computed tomography scan. At laparotomy, a perforated appendix was identified, with histopathology identifying a perforated LAMN. This case highlights the importance of considering this rare but increasing incidence tumour when operative management is being planned.