Decidualized Juvenile Cystic Adenomyoma Mimicking a Cornual Heterotopic Pregnancy

Abstract

<h3>Study Objective</h3> To describe a rare case of a juvenile cystic adenomyoma presenting as a heterotopic pregnancy. <h3>Design</h3> Case report. <h3>Setting</h3> Private teaching hospital. <h3>Patients or Participants</h3> A 26-yo G3P1 at 7wga presented to the emergency department with complaint of vaginal spotting and mild cramping. Ultrasound identified a heterotopic pregnancy. An intrauterine pregnancy was noted with a 1.9cm gestational sac, a 1.1cm CRL, and FHR 161bpm. A second gestational sac was noted in the posterior left uterus measuring 1.58cm with CRL 0.94cm and <5mm of myometrium surrounding the sac. No cardiac activity detected. <h3>Interventions</h3> The patient was counseled regarding options for management including abortive vs non-abortive, medical vs surgical. She ultimately decided to undergo surgical treatment with preservation of the intrauterine pregnancy. Intraoperative laparoscopic ultrasound was performed with similar findings. Robotic assisted cornual wedge resection and removal of the ectopic mass was performed with preservation of the ipsilateral fallopian tube and intrauterine pregnancy. <h3>Measurements and Main Results</h3> Final pathology failed to demonstrate any fetal tissue, but rather demonstrated cystic adenomyoma. <h3>Conclusion</h3> Juvenile cystic adenomyosis (JCA) is a rare form of focal adenomyosis which is usually located near the uterine insertion of the round ligament, contains a cystic inner area >1cm and is encountered before the age of 30 years. Some authors report JCA to be an accessory cavitated uterine mass (ACUM) anomaly developing because of gubernaculum dysfunction. The only difference between the two conditions is the presence of a denser area of adenomyosis surrounding the cystic area lined with endometrium in JCA. This case demonstrates decidual changes observed in ectopic endometrial tissue within an area may be misdiagnosed as a focus of ectopic pregnancy. In non-emergency situations, waiting for the decidualization effect of ectopic endometrium to subside can help in the definitive diagnosis of such cases.