Focal adenomyoma is a well-circumscribed nodular lesion composed of smooth muscle tissue, endometrial glands, and endometrial stroma. It may be intrauterine or, rarely, extrauterine. Ovarian ligament involvement is rare, with only 12 case reports documented in the literature to date [1,2]. Due to its rarity, there is currently no consensus on the optimal diagnostic or therapeutic approach. A 39-year-old woman, married for 15 years, gravida 3, para 0, with a history of three Cesarean sections, presented to a medical center with progressively worsening chronic pelvic pain (CPP), pelvic heaviness, severe congestive dysmenorrhea, and gastrointestinal symptoms, including flatulence, dyspepsia, and indigestion, for 6 months. The patient reported intermittent episodes of right pelvic pain. The patient was on oral contraceptive therapy and expressed no desire to conceive. An abdominal examination revealed tenderness of the right iliac fossa and fullness of the right vaginal fornix. Emergency transvaginal ultrasonography revealed a right adnexal mass, measuring 6×10 cm, with a heterogeneous echotexture, showing mixed echogenic, hypoechoic, and hyperechoic components. Doppler ultrasonography demonstrated preserved ovarian blood flow and diffusely arranged intralesional vessels (Fig. 1A). Magnetic resonance imaging (MRI) was also performed and showed a right adnexal mass, separate from the uterus and in close proximity to the right ovary, without a precise origin (Fig. 1B-D). Importantly, the MRI report concluded that this was a suspicious case owing to its heterogeneity. Laboratory results indicated normal levels of tumor markers. Following proper counselling and preparations, a Pfannenstiel mini-laparotomy revealed a big (7×10 cm) vascular, firm, and heterogeneous right adnexal mass embedded in the right ovarian fossa and pouch of Douglas. Unexpectedly, the mass originated from the right ovarian ligament and bled upon contact (Fig. 2A). The right ovary and fallopian tubes appeared normal (Fig. 2B). The mass was excised using a monopolar electrode (Fig. 2C), and the ovarian ligament was reconstructed (Fig. 2D). Upon completion of the procedure, peritoneal lavage was performed, anti-adhesion sheets were applied, and an intraperitoneal drain was placed. The drain was removed the following morning, and the patient was discharged the same day after an uneventful postoperative course. The final histopathological diagnosis was a localized (focal) adenomyoma of the ovarian ligament without malignant changes (Fig. 3). During the 6-month follow-up, the patient reported a marked reduction in pelvic pain, with the visual analog scale (VAS) score decreasing from severe preoperative levels (8/10) to mild discomfort (1 to 2/10). Moreover, regular analgesics were no longer required. Menstrual symptoms also improved significantly. In particular, with congestive dysmenorrhea and pelvic heaviness resolved. The serial ultrasonographic examinations were also unremarkable. Furthermore, no hormonal or other adjuvant therapies were required. In recent years, there has been growing interest in focal uterine and extrauterine adenomyomata [1,2]. A focal adenomyoma typically appears hypointense on T2-weighted MRI images, reflecting the low vascularity and limited water content of its predominant smooth muscle component, and may closely mimic the appearance of leiomyomas [3]. However, as illustrated in Figure 1, the presence of multiple scattered hyperintense foci within an otherwise heterogeneous hypointense lesion corresponding to ectopic endometrial glands represents a useful distinguishing feature. These hyperintense foci in adenomyomas remain visible on T2-weighted images irrespective of the menstrual cycle phase, owing to the higher vascularity and water content of the endometrial component [3]. By contrast, leiomyomas usually demonstrate a homogeneous T2 hypointense signal in the absence of degenerative changes. Other differential diagnoses, such as ovarian endometriomas and solid ovarian tumors, are distinguishable based on clinical and imaging characteristics. The histological diagnosis of a triad of smooth muscle tissues, endometrial glands, and characteristic endometrial stroma distinguishes adenomyoma from leiomyoma or secondary smooth muscle hyperplasia, and rules out low-grade smooth muscle neoplasms. However, immunohistochemical studies were not required. The extreme rarity of extrauterine adenomyomas contributes to the difficulty of diagnosing their origin in the ovarian ligament. Surprisingly, a delicate structure, such as the ovarian ligament, which is composed primarily of fibrous tissue, can harbor a large adenomyoma measuring approximately 11 cm. This can be explained by the proliferation and differentiation of multipotent cells within the subcoelomic mesenchymal layer into endometrial glands, stroma, and smooth muscle cells under hormonal stimulation [4]. This pathogenic concept is consistent with other reported extrauterine adenomyomas arising at sites, such as the broad ligament, round ligament, and peritoneum, where lesions are thought to originate from Müllerian remnants or the subcoelomic mesenchyme undergoing hormonally driven differentiation. The present case supports the view that ovarian ligament adenomyoma represents part of the same spectrum of extrauterine adenomyotic diseases rather than an isolated entity. Unlike diffuse adenomyosis, symptomatic focal adenomyomas can only be managed surgically. In this case, mini-laparotomy was performed to prioritize patient safety, as laparoscopic intervention was excluded due to several factors: multiparity, history of three Cesarean sections with suspected pelvic adhesions, heterogeneous appearance on ultrasonography, inconclusive nature and origin of the mass on MRI, and the patient ’s family. Additionally, the large size of the mass and the potential risk of tissue or cell dissemination during morcellation, even when using an endobag, further justify the choice of a mini-laparotomy approach. Intraoperatively, the vascular surface and heterogeneous appearance supported this decision. Consequently, no post-operative adjuvant or hormonal therapy was required. In conclusion, fertility-preserving surgical excision for rare ovarian ligament adenomyomas is a feasible and curative procedure. Gynecologists are encouraged to report similar cases to determine the prevalence of focal adenomyoma and build a body of knowledge relevant to clinical gynecology.