A novel and rare diverticulum-like adenomyosis: A case report

INTRODUCTION: Cystic adenomyosis is a rare variant of adenomyosis, with only 90 reported cases found in the literature so far. Diverticulum-like adenomyosis is even more uncommon, with only one documented case to date. CASE PRESENTATION: We report the case of a 42-year-old asymptomatic woman who had an incidental finding of a parauterine cyst on an abdominal computed tomography scan. B-ultrasonography also revealed an endometriotic cyst. Further MRI revealed a cystic lesion measuring 7.6 × 6.1 × 7.7 cm that communicated with the uterine cavity through a tiny channel. The fluid in the cyst showed high signal intensity on T1-weighted image (T1WI), and the cyst wall showed a marked low signal intensity on T2-weighted image (T2WI). No other masses were found on either side. After obtaining informed consent, we performed a laparoscopic exploration on the patient, where it became apparent that the 7.6 × 6.1 × 7.7 cm cystic mass was located on the left uterine isthmus—the excised lesion contained chocolate-like fluid within a thickened wall. Pathological examination revealed typical endometrial glands and interstitial tissues in the cystic wall. DISCUSSION: Cystic adenomyosis is a rare benign lesion in women of reproductive age that is known to cause hypermenorrhea, dysmenorrhea, and abnormal uterine bleeding. Our case represents the second documented case of diverticulum-like adenomyosis. However, the patient in our case did not exhibit abnormal uterine bleeding or dysmenorrhea. One possible explanation for this finding is that the sinus tract was too small to cause blood influx into the uterine cavity. CONCLUSION: Our case report provides valuable insights for clinicians to better understand this uncommon disease and reduce the incidence of misdiagnosis.