Unexpected histopathology of acute appendicitis

•Diverticulitis of appendix is rare problem and rarely diagnosed preoperatively.•We recommended to inspect all appendix specimen and thorough examination of peritoneal cavity during surgery.•Appendicular diverticulitis is considered as an alarming feature due to its strong malignant association.•Radiological proven diverticula of appendix, we would also recommend elective intervention due to higher risks of potential complications such as perforation and hemorrhage. Appendicular diverticula and associated diverticulitis is a rare disease. Patients present commonly with symptoms of acute appendicitis and require laparoscopic or open surgery. Diagnosis is usually made only on histology. Here, we present a rare case of acute diverticulitis of the appendix. A 33-year old gentleman presented with right iliac fossa pain of 3 days duration. On admission, appendicitis was diagnosed on Computerized Tomography (CT) scan and laparoscopic appendicectomy was subsequently performed. Intra-operative findings were unremarkable and recovery was uneventful. Histopathology however revealed diverticulitis of appendix with acellular mucin. Acute diverticulitis of the appendix is an exceptionally rare condition and reported in 0.004%–2% of appendicectomies. It presents usually when complicated with perforation and bleeding. There is however a strong association with certain malignancies such as mucinous neoplasm, carcinoid and Pseudomyxoma peritoneii. Radiological proven appendicular diverticulum requires early intervention due to higher chance of diverticulitis related complication. Surgeons should be aware about this rare disease and may consider elective surgery in view of potential risk of complications and malignancy. We concluded that because of strong malignant association, it would be recommended that all appendix specimens should inspect during and after surgery and concurrent examination of peritoneal cavity is recommended.