Decidualized juvenile cystic adenomyoma mimicking a cornual pregnancy.

<bold>Objective: </bold>To demonstrate the laparoscopic excision technique of a juvenile cystic adenomyoma and show how the decidualization of ectopic endometrial tissue can lead to the misdiagnosis of a focus of ectopic pregnancy.<bold>Design: </bold>Description and step-by-step demonstration of the surgical procedure using a video recording (Canadian Task Force Classification 3).<bold>Setting: </bold>Teaching and research hospital.<bold>Patient(s): </bold>A 27-year-old gravida 2 parity 1 patient with one previous caesarean delivery presented to the emergency department with symptoms of pelvic pain and delayed menses. Her beta-human chorionic gonadotropin level was 2,161 mIU/mL. On transvaginal ultrasonography the uterine cavity appeared empty without any signs of a gestational sac, and a 42×45 mm heterogeneous mass was observed on the right cornual area. An 18×21 mm cystic area was observed within the mass. A diagnosis of cornual pregnancy was made and two doses of systemic methotrexate treatment were administered. On the 12th day following medical treatment, the patient reported increasing abdominal pain and free fluid was observed in the pouch of Douglas on ultrasonography. The decision to perform laparoscopic cornual excision was made.<bold>Main Outcomes and Measure(s): </bold>On laparoscopic exploration a tubal ectopic pregnancy was observed within the left fallopian tube. The presence of two simultaneous ectopic pregnancies, located in the left fallopian tube and the right cornual area, was suspected. However, upon careful inspection, the right fallopian tube appeared normal and the mass initially thought to be a right cornual pregnancy appeared more like a degenerated fibroid. A left salpingectomy was performed and the excision of the mass in the right cornual area was planned. An incision was made over the mass and the cystic inner area containing chocolate-brown colored fluid was drained. As there was no pseudo capsule surrounding the mass, the diagnosis of focal adenomyosis instead of degenerated fibroid was made. No endometriotic foci were observed within the pelvis. Different from the enucleation of a fibroid, the mass was dissected from the middle into two halves until healthy myometrium was reached on the floor of the mass. The two halves of the mass were resected totally by dissecting the adenomyotic tissue from the myometrium starting from the caudal end towards the cranial end. The first layer of the remaining myometrial defect was sutured extracorporeally with No.1 polyglactan sutures. The second and third layers were sutured intracorporeally with V-loc sutures. The resected left fallopian tube containing the ectopic pregnancy and the adenomyotic mass were externalized through a posterior colpotomy incision.<bold>Result(s): </bold>The patient was discharged 24 hours postoperatively without any complications. A diagnosis of juvenile cystic adenoma was made upon histopathological examination. The patient reported subsiding of her dysmenorrhea on the postoperative third month.<bold>Conclusion(s): </bold>Juvenile cystic adenomyosis (JCA), is a rare form of focal adenomyosis which is usually located in close proximity to the uterine insertion of the round ligament, contains a cystic inner area larger than 1 cm and is encountered before the age of 30 years. Some authors reported JCA to be an accessory and cavitated uterine mass (ACUM) anomaly developing as a result of gubernaculum dysfunction. The only difference between the two conditions is reported to be the presence of a denser area of adenomyosis surrounding the cystic area lined with endometrium in JCA than in ACUM. This case has shown that decidual changes observed in ectopic endometrial tissue within an adenomyotic area may be misdiagnosed as a focus of ectopic pregnancy. Atypical endometriomas demonstrating decidual changes may also be misdiagnosed as ovarian malignancies. In non-emergency situations, waiting for the decidualization effect of ectopic endometrium to subside can help in the definitive diagnosis of such cases. Our technique for JCA excision is different from enucleation of a fibroid and may aid in the total resection and dissection of the adenomyotic tissue from healthy myometrium. [ABSTRACT FROM AUTHOR]