BACKGROUND Acute appendicitis is common in older patients, however, the presentation may differ from the younger population and it is often complicated by coexistent disease and delays in presentation. OBJECTIVE This case report describes an unusual presentation of acute appendicitis in an elderly patient and also demonstrates a unique anatomical pathway of disease extension. In addition, this case report highlights the advantages of CT in preoperative evaluation and subsequent management of these protean presentations of acute appendicitis. METHODS This report describes a case of an asymptomatic retrocaecal perforated appendicitis which presented clinically as a right lumbar abscess with surrounding cellulitis, and was further complicated by a concomitant new diagnosis of type 2 diabetes mellitus in a 66-year-old male. CONCLUSIONS Elderly or immunocompromised patients presenting with cellulitis or a cutaneous abscess of the abdominal wall or lumbar region may benefit from an abdominal CT to demonstrate an intraperitoneal source of sepsis.