Introduction: Inverted Meckel's diverticulum has usually been misdiagnosed in the cases based on computed tomography images presented in the literature. The final diagnosis was made intra-operatively or by pathology reports after surgery. Despite this, preoperative diagnosis could be made successfully by using endoscopic ultrasound with double-balloon endoscopy prior to surgery.
Case presentation: A 60-year-old Japanese woman with severe anemia complained of several episodes of black stool over the preceding 2 years. Abdominal computed tomography showed a 3.0-cm low-density tumor in the ileum, suggesting a diagnosis of intestinal lipoma. Examination of the tumor by endoscopic ultrasound with double-balloon endoscopy revealed a hypo-echoic layer corresponding to the muscularis propria, and a hyper-echoic layer corresponding to the fat tissue. These findings, which suggested that the tumor included areas outside the intestinal serosa, are not typical for a lipoma, despite the existence of a hyper-echoic layer corresponding to fatty tissue. We then considered a diagnosis of inverted Meckel's diverticulum.
Conclusion: Lipoma and inverted Meckel's diverticulum are difficult to differentially diagnose by computed tomography. Polypectomy is the preferred therapeutic approach when a lipoma is present; however, polypectomy in a patient with Meckel's diverticulum requires full-thickness resection. Situations where polypectomy is performed without preparing for full-thickness resection can be avoided by first making a precise diagnosis using double-balloon endoscopy and endoscopic ultrasound.