A Case of Acute Appendicitis in the Presence of a Riedel Lobe Affecting Abdominal Examination and Laparoscopic Surgery

Abstract

A 47-year-old woman was referred to us for evaluation of abdominal pain. Physical examination showed a palpable non-tender right lower abdominal mass (approximately 3 cm in diameter), accompanied by localized tenderness in the right pelvic cavity. Abdominal computed tomography (CT) revealed a Riedel’s lobe extending to the right lower abdomen and an edematous appendix anterior to the right pelvic cavity. We diagnosed the patient as having acute appendicitis and performed laparoscopic appendectomy, paying close attention to avoiding injury to the Riedel’s lobe. Following an uneventful procedure, the patient was discharged on the fifth postoperative day without complications. Riedel’s lobe, a congenital hepatic anomaly, refers to a tongue-like projection extending from the right lobe of the liver to below the umbilicus. It may be palpable as a right lower abdominal mass, potentially interfering with the diagnostic process during medical examination. Extreme caution is warranted during surgical procedures in the presence of anatomical variations, owing to the risk of inadvertent organ injury. Based on CT-documented data at our hospital, Riedel’s lobe was identified in 40/410 patients (9.8%), which highlights the relatively frequent occurrence of this abnormality. Clinicians should be mindful of this anomaly in patients presenting with right lower abdominal conditions, including appendicitis.