The patient was a 66-year-old man who presented to our hospital with intermittent abdominal pain. Abdominal ultrasound showed a mass presenting as a target sign in the right abdomen, suggesting intussusception. Subsequent computed tomography (CT) and lower gastrointestinal endoscopy revealed a 5 cm lipoma in the ascending colon. The intussusception had resolved spontaneously, so the patient was followed up on an outpatient basis. Although endoscopic treatment was considered for the lipoma, due to its large size, the patient was referred to our department for surgery 1 month later. A follow-up CT scan revealed a recurrence of the intussusception. Because the patient tolerated oral intake, had normal bowel movements without symptoms of bowel obstruction, and experienced only mild abdominal pain, conservative outpatient observation was continued until laparoscopic-assisted ileocecal resection was performed. The postoperative course was uneventful, and the patient was discharged on postoperative day 8 without any complications. Colonic lipoma causing intussusception is relatively rare. Since lipoma is a benign disease, it is a good candidate for laparoscopic surgery, which offers excellent cosmetic outcomes and rapid postoperative recovery. Even in cases with intussusception, when there is no bowel obstruction and the abdominal pain is mild, elective surgery within 1-3 months can be considered a viable option.

Metronidazole is an effective antibacterial agent against anaerobic bacteria, and its use in the gastrointestinal field, particularly in patients with intra-abdominal infections, has increased with the availability of injectable formulations. However, a known side effect of metronidazole is central nervous system impairment, namely, metronidazole-induced encephalopathy. Here, we present a case of a 68-year-old man who underwent laparoscopic abdominoperineal resection for rectal cancer in March of year X. Postoperatively, metronidazole was administered for pelvic dead space infection and perineal wound infection, and the patient continued the oral medication after discharge. In May of year X, the patient was referred to our institution near his home for postoperative adjuvant chemotherapy. In February of year X+1, the patient developed dysarthria, and a FLAIR (fluid-attenuated inversion recovery) image on head magnetic resonance imaging revealed bilaterally symmetric hyperintense lesions in the dentate nuclei of the cerebellum. Suspecting metronidazole-induced encephalopathy based on the medication history, metronidazole was discontinued, leading to symptom improvement within approximately 3 days. We diagnosed metronidazole-induced encephalopathy based on the imaging findings and clinical observations. When using metronidazole, we should pay attention to the dosage and duration of administration and make efforts to detect side effects early.