When Meckel's diverticulum mimics malignancy: a case report of massive enterolithiasis in an adult patient.

Introduction and importance: Meckel's diverticulum (MD) is the most common congenital anomaly of the gastrointestinal tract, resulting from incomplete obliteration of the vitelline duct. It typically presents in early childhood and is most often diagnosed by age two. Adult presentations, especially in the elderly, are rare and frequently misdiagnosed due to their nonspecific symptoms or unusual radiographic findings. Presentation of case: A patient in her 70s with a remote history of total abdominal hysterectomy for benign indications presented with abdominal distention, altered bowel habits, and a palpable pelvic mass. Imaging revealed a 9-cm calcified mass contiguous with small bowel, initially suspected to be an ovarian dermoid tumor. Exploratory laparotomy with general surgery and gynecologic oncology revealed a large MD containing multiple cholesterol stones. Segmental small bowel resection was performed. Final pathology confirmed massive enterolithic diverticular impaction, consistent with underlying MD. No malignancy was identified. Clinical discussion: This case illustrates the diagnostic challenge of MD in older adults, where atypical presentations may mimic gynecologic pathology. The presence of multiple cholesterol enteroliths is exceptionally uncommon and may be related to altered bile physiology after cholecystectomy. Recognition of such unusual presentations emphasizes the importance of multidisciplinary evaluation in patients with complex abdominopelvic masses. Conclusion: Elderly patients with pelvic or abdominal masses should be evaluated with gastrointestinal etiologies in mind, particularly when prior surgical history alters anatomic interpretation. Awareness of atypical manifestations of MD can prevent misdiagnosis and guide timely surgical management.