A misleading case of Müllerian anomaly: fibroid degeneration and growth involving nonfunctional, noncommunicating rudimentary horn

Objective: To report a rare, misleading fibroid degeneration involving a nonfunctional, noncommunicating horn in a woman with a unicornuate uterus. Although the presence of a functional rudimentary horn may lead to signs and symptoms that recommend its removal, nonfunctional cases are rarely reported, and because of their apparent functional inactivity, the need for their removal has not yet been reported. No previous report showed the possibility of a degenerative process in a nonfunctional rudimentary horn causing patient discomfort. Design: This is a step-by-step narrated video showing a unique case of fibroid degeneration and growth of a nonfunctional, noncommunicating rudimentary horn in a unicornuate uterus (American Society for Reproductive Medicine classification 2021) and its surgical management. Setting: University academic hospital. Patient(s): A 48-year-old White nulliparous premenopausal woman was referred to our institution because of abdominal pain and an enlarging adnexal mass. Her personal history showed primary infertility with a previous diagnosis of unicornuate uterus. Given the possibility of ectopic ureters in these occurrences, complete computed tomography was performed, and no genitourinary alterations were found. Preoperative imaging (ultrasound evaluation, computed tomography, and magnetic resonance imaging) provided a provisional diagnosis of a suspicious ovarian fibroma. Intervention(s): Considering the patient's age, lack of desire for pregnancy, and volumetric increase in the adnexal mass, a laparoscopic intervention to perform mass removal and prophylactic bilateral salpingectomy was planned. The patient was counseled about the low risk of an underlying malignant transformation. Therefore, the decision to remove the intact mass via a minilaparotomy at the end of the surgery was shared. Once the abdominal cavity was entered, the right unicornuate uterus was found in anatomical continuity with the ipsilateral broad ligament, fallopian tube, and ovary. These structures were wholly attached to the right pelvic wall. On the other side, cranially compared with the right hemiuterus, a roundish myoma-like mass was detected in direct connection with the left broad ligament, fallopian tube, and ovary. In light of a changed intraoperative finding, amputation of the left rudimentary horn and prophylactic bilateral salpingectomy were performed. Main Outcome Measure(s): Showing the fibroid degeneration and growth of a nonfunctional, noncommunicating rudimentary horn in a unicornuate uterus (American Society for Reproductive Medicine classification 2021) treated laparoscopically. Result(s): Laparoscopic removal of the uterine horn was successful, and no intraoperative and postoperative complications occurred. The patient was in good health at the 6-month follow-up visit. The histopathological examination confirmed the fibroid degeneration and absence of the endometrium. Conclusion(s): The lack of symptomatic cases of rudimentary nonfunctional horns reported in the literature led gynecologists to consider them a silent Müllerian anomaly. This unique case demonstrates that even nonfunctional rudimentary horns can undergo symptomatic transformation processes requiring surgery. This information may be helpful for more comprehensive counseling of women and for considering the possibility of this occurrence in the diagnostic workup of misleading Müllerian anomalies. With this in mind, surgical treatment can also be better planned as the technical aspects change compared with what is expected for an adnexal pathology.