{"paper_id":"18331121-8b01-40a9-acc7-b5a5ba72da5f","body_text":"Review began\n 09/08/2026 \nReview ended\n 10/05/2026 \nPublished\n 10/09/2026\n© Copyright \n2026\nGarcía-Gudiño et al. This is an open\naccess article distributed under the terms of\nthe Creative Commons Attribution License\nCC-BY 4.0., which permits unrestricted use,\ndistribution, and reproduction in any\nmedium, provided the original author and\nsource are credited.\nDOI:\n 10.7759/cureus.117684\nOvarian Fibroma Mimicking an Endometrioma in\na Postmenopausal Patient: A Diagnostic\nChallenge in a Solid Adnexal Mass With Low Risk\nof Ovarian Malignancy Algorithm (ROMA) Index\nVanessa García-Gudiño \n, \nEmiliana Arcos-Ayala \n \n, \nSantiago Córdova-Egüéz \n, \nHugo Garzón-Ávila \n,\nFedra Vela-Merino \n1.\n Department of Obstetrics and Gynecology, Hospital Metropolitano, Quito, ECU \n2.\n School of Medicine, Universidad\nSan Francisco de Quito, Quito, ECU \n3.\n Department of Medical Education, Hospital Metropolitano, Quito, ECU\nCorresponding author: \nEmiliana Arcos-Ayala, \nemiliana.arcos@gmail.com\nAbstract\nOvarian fibromas are uncommon benign sex cord-stromal tumors that frequently present as unilateral solid\nmasses and may mimic ovarian malignancy, particularly in postmenopausal women. Preoperative diagnosis\nremains challenging because imaging findings and tumor markers often overlap with those of other adnexal\nlesions. We present the case of an ovarian fibroma initially misdiagnosed as an endometrioma, illustrating\nthe limitations of preoperative assessment. We report the case of a 60-year-old postmenopausal woman\nwith an incidentally detected right adnexal mass initially interpreted as an endometrioma on transvaginal\nultrasound and computed tomography (CT). The patient subsequently underwent laparoscopic resection,\nand histopathological examination confirmed the diagnosis of ovarian fibroma. Ovarian fibromas may mimic\nother adnexal masses, making preoperative diagnosis challenging. Imaging studies and serum tumor\nmarkers have limited specificity and may be insufficient to reliably distinguish these tumors from other\novarian lesions. In postmenopausal women, persistent solid adnexal masses generally warrant surgical\nexploration regardless of ancillary findings. Therefore, definitive diagnosis of ovarian fibroma relies on\nhistopathological examination. Ovarian fibroma remains an important differential diagnosis of solid\nadnexal masses in postmenopausal women. The limitations of preoperative assessment reinforce the role of\nsurgical excision, while histopathological examination remains the gold standard for definitive diagnosis.\nCategories:\n Obstetrics/Gynecology, Oncology\nKeywords:\n adnexal mass, endometrioma, ovarian fibroma, postmenopause, roma index\nIntroduction\nAmong ovarian tumors, fibromas are the most common type of tumor arising from cells of the sex cord\nstroma. They are benign, relatively rare, and account for 4% of ovarian tumors. They can occur at any stage\nof a woman's life, with the highest prevalence (77%) during reproductive age \n[1]\n. They usually present\nunilaterally in approximately 90% of cases. Their size varies, with an average diameter of about 6 cm. They\nare characterized by slow growth, although they can reach considerable sizes \n[2]\n.\nLarger ovarian fibromas carry a substantially higher risk of complications, notably ascites and ovarian\ntorsion, making tumor size a critical factor in clinical prognosis \n[3]\n. Clinical presentation is variable and\ncovers a wide spectrum. While many patients are completely asymptomatic, others may present with non-\nspecific lower abdominal or pelvic symptoms, including chronic pelvic pain, localized discomfort, abdominal\ndistension, a palpable mass, or compressive symptoms affecting adjacent organs, such as urinary frequency\nor bowel habit changes. In other instances, the condition is discovered as an incidental finding in imaging\nstudies, or it can present with complications such as ascites and pleural effusion, a clinical picture\ncharacteristic of Meigs syndrome \n[4]\n.\nThe diagnostic workup for these tumors includes laboratory testing and imaging modalities to guide the\ndiagnosis. On computed tomography (CT), these lesions typically present with variable attenuation, solid\ndense components, or degenerative cystic changes that closely mimic endometriomas or malignant lesions.\nHowever, definitive diagnosis is achieved exclusively through histopathology. As solid tumors of stromal\norigin, they are frequently accompanied by elevated CA-125 levels, particularly when associated with Meigs\nsyndrome. Nonetheless, this marker can be elevated in benign conditions and even in 2% of healthy women.\nTherefore, its clinical utility remains controversial, and there is currently no specific biomarker for ovarian\nfibromas \n[5]\n. \nIn this scenario, the evaluation of a solid adnexal mass in a postmenopausal patient remains a clinical\nchallenge despite advancements in imaging and the use of tumor markers. Furthermore, preoperative\ndifferentiation between benign and malignant lesions continues to be limited, particularly regarding stromal\ntumors. Herein, we present the case of a postmenopausal patient with a solid adnexal mass whose initial\n1\n2,\n3\n1\n1\n1\n \nOpen Access Case Report\nHow to cite this article\nGarcía-Gudiño V, Arcos-Ayala E, Córdova-Egüéz S, et al. (October 09, 2026) Ovarian Fibroma Mimicking an Endometrioma in a Postmenopausal\nPatient: A Diagnostic Challenge in a Solid Adnexal Mass With Low Risk of Ovarian Malignancy Algorithm (ROMA) Index. Cureus 18(10): e117684.\nDOI 10.7759/cureus.117684\n\nimaging diagnosis suggested an endometrioma, but whose histopathological examination ultimately\nconfirmed an ovarian fibroma.\nCase Presentation\nA 60-year-old postmenopausal woman (10 years postmenopause) with a medical history of Sjögren's\nsyndrome, under occasional treatment with methotrexate and folic acid, presented for a routine\ngynecological evaluation after several years of lost follow-up. Past surgical history included a hysterectomy\nfor abnormal uterine bleeding 20 years prior. Her obstetric history noted gravida 3, para 1, abortus 2, with\none living child (G3P1A2). She was not currently sexually active. No other significant history was noted.\nBaseline laboratory exams showed mild leukopenia as the only remarkable finding.\nThe patient reported no active symptoms such as acute pelvic pain, abnormal bleeding, or systemic B-\nsymptoms; her presentation was entirely asymptomatic. During this routine evaluation, a transvaginal\nultrasound was performed, which incidentally revealed a solid mass in the right ovary measuring\napproximately 50 × 46 × 64 mm (volume: 67 mL), with no free fluid in the pouch of Douglas. No other\nabnormalities were detected. \nBased on the mentioned findings, a non-contrast and contrast-enhanced computed tomography (CT) scan\nof the abdomen and pelvis was requested (Figure \n1\n). It revealed an ovoid-shaped mass in the right adnexa\nwith cystic-dense content (20-45 HU) and well-defined margins showing mild contrast enhancement,\nmeasuring 57 × 41 mm in its largest diameters, compatible with an endometrioma. To further characterize\nthe tumor behavior, serum tumor markers were ordered (Table \n1\n). All results were within the reference\nranges, and the Risk of Ovarian Malignancy Algorithm (ROMA) index indicated a low risk of malignancy. \nFIGURE\n 1: Non-contrast and contrast-enhanced abdominopelvic\ncomputed tomography (CT) showing a right adnexal mass.\n(A) Axial view showing a well-circumscribed right adnexal mass with maximal dimensions (5.7 cm × 4.1 cm at its\ngreatest diameters). (B) Axial view showing an ovoid-shaped lesion with dense cystic content (20-45 HU) and\nwell-defined borders after contrast administration. (C) Coronal reconstruction demonstrating the location of the\nright adnexal mass. (D) and (E) Additional axial images illustrating the relationship of the lesion with adjacent\npelvic structures. (F) Three-dimensional reconstruction indicating the anatomical location of the mass. \n \n2026 García-Gudiño et al. Cureus 18(10): e117684. DOI 10.7759/cureus.117684\n2\n of \n6\n\nLaboratory test\nPatient value\nReference range\nβ-hCG\n1.36 mIU/mL\n<5.0 mIU/mL (non-pregnant)\nAlpha-fetoprotein\n4.33 µg/L\n0-10 µg/L\nCA-125\n23.20 U/mL\n<35 U/mL\nCA 15-3\n9.90 U/mL\n<25 U/mL\nHE4\n65 pmol/L\n<140 pmol/L (postmenopausal)\nROMA index\n18.95%\nReference cutoff (postmenopausal): <27.7%\nTABLE\n 1: Preoperative serum tumor marker results and corresponding reference ranges.\nβ\n-hCG: beta-human chorionic gonadotropin; ROMA: Risk of Ovarian Malignancy Algorithm.\nGiven the presence of a persistent solid adnexal mass in a postmenopausal woman, surgical management\nvia operative laparoscopy was decided. During the procedure, a solid right ovarian mass was observed,\nmeasuring approximately 6 cm in diameter, with a regular surface and a whitish appearance (Figure \n2\n). A\ntotal surgical resection was performed. Gross pathological examination revealed multiple whitish fragments\nweighing 40 g in total, with a whirled, whitish cut surface (Figure \n3\n). Microscopic analysis showed a\nproliferation of bland spindle cells with ovoid nuclei and scanty cytoplasm, accompanied by an extensively\ncollagenized interstitium, without mitotic activity. No necrosis was identified (Figure \n4\n). These findings\nwere compatible with an ovarian fibroma. Finally, the patient had a satisfactory postoperative course\nwithout complications.\nFIGURE\n 2: Intraoperative laparoscopic findings. \n(A) and (B) A solid mass (*) arising from the right ovary is observed, well-circumscribed relative to adjacent\nstructures. It features a smooth surface, pearly appearance, and firm consistency. (C) and (D) Protocol-based\noophorectomy, initiated at the infundibulopelvic ligament using advanced bipolar energy.\n \n2026 García-Gudiño et al. Cureus 18(10): e117684. DOI 10.7759/cureus.117684\n3\n of \n6\n\nFIGURE\n 3: Gross anatomy of the resected right ovarian mass\ndemonstrating multiple fragmented tissue specimens.\nThe sectioned surfaces exhibit a characteristic firm, whirled, grayish-white solid appearance typical of an ovarian\nfibroma. No obvious areas of hemorrhage or macroscopic cystic necrosis were evidenced.\nFIGURE\n 4: Histopathological study of the ovarian tumor with\nhematoxylin and eosin (H&E) staining.\n(A) Low-power panoramic view (4×) showing a well-circumscribed solid lesion. (B) Intermediate magnification\n(10×) demonstrating a diffuse proliferation of spindle cells arranged in short fascicles. (C) High-power\nmagnification (40×) showing spindle cells with ovoid nuclei, bland cytology, without significant atypia or mitotic\nactivity, embedded in an abundant collagenous stroma. These findings are compatible with an ovarian fibroma.\nDiscussion\nAlthough ovarian fibroma represents the most prevalent benign sex cord-stromal tumor \n[6]\n, its\nmanifestation as a unilateral solid mass in postmenopausal females can pose a diagnostic dilemma, as any\nsolid tumor within this cohort must be presumed potentially malignant until proven otherwise \n[7]\n. While\ntransvaginal ultrasonography serves as the first-line diagnostic modality for evaluating ovarian masses \n[8]\n,\nits findings can frequently overlap with other adnexal entities. Thus, computed tomography (CT)\nconstitutes a valuable adjunctive tool \n[9]\n.\nNonetheless, in the presented case, the lesion was initially categorized as a suspected endometrioma, an\n \n2026 García-Gudiño et al. Cureus 18(10): e117684. DOI 10.7759/cureus.117684\n4\n of \n6\n\nentity that is exceptionally rare in postmenopausal females \n[10]\n. Confirmatory histopathology revealed an\novarian fibroma, underscoring the suboptimal specificity of imaging modalities in characterizing stromal\ntumors. Current evidence demonstrates that computed tomography (CT) exhibits limited diagnostic\nperformance and can mislead the preoperative characterization of adnexal masses. Consequently, its utility\nas a first-line tool for initial evaluation is not supported \n[11]\n. \nMoreover, MRI plays a fundamental role in evaluating ovarian tumors, enabling patient stratification into\nlow- or high-risk categories for malignancy, with a reported specificity of approximately 76% \n[12]\n. Key\ndiagnostic benefits of MRI rely on structural tissue characterization; findings indicative of ovarian\nfibromas/thecomas include characteristic hypointensity on T2-weighted imaging, specific diffusion\ncoefficients, and moderate enhancement profiles \n[13]\n. Nevertheless, this study was omitted in our patient.\nAlthough MRI improves diagnostic precision in selected cases, factors such as cost and accessibility limited\nits use, justifying immediate surgical resolution. Consequently, performing an MRI would not have modified\nthe clinical decision to pursue prompt surgical exploration.\nOn the other hand, serum tumor biomarkers and the ROMA index indicated a low risk of malignancy.\nHowever, it is critical to note that the ROMA index has been validated primarily for epithelial ovarian\ntumors; consequently, its predictive value for sex cord-stromal tumors remains limited \n[14]\n. While the\nabsence of ascites and elevated CA-125 levels effectively ruled out Meigs syndrome, it did not entirely\nexclude malignancy. Stromal neoplasms can present with elevated CA-125, yet this biomarker may also rise\nin benign conditions and in up to 2% of healthy individuals \n[15]\n. Therefore, its diagnostic utility is\ncontroversial, and no specific biomarker currently exists for ovarian fibromas. Furthermore, current clinical\nmanagement guidelines dictate that a persistent solid adnexal mass in a postmenopausal female warrants\nsurgical evaluation regardless of benign ancillary imaging or biomarker findings, given the significantly\nelevated baseline risk of malignancy within this age group \n[11,16,17]\n. Although the initial radiological\nimpression suggested an endometrioma, surgical exploration was pursued to mitigate potential\ncomplications. Ultimately, this surgical approach enabled definitive diagnostic confirmation via\nhistopathology, which remains the gold standard for these lesions. This case highlights an important\ndiagnostic triad in postmenopausal women--a persistent solid adnexal mass, low ROMA index/normal\ntumor markers, and misleading imaging characteristics, such as CT density mimicking an endometrioma.\nIdentified together, these features emphasize that low-risk markers should not rule out surgical exploration\nwhen solid adnexal architecture is present.\nConclusions\nOvarian fibroma is the most prevalent benign sex cord-stromal tumor and must be included in the\ndifferential diagnosis of any solid adnexal mass, particularly in postmenopausal females. Current evidence\nsupports a comprehensive diagnostic approach integrating clinical findings, imaging modalities, and tumor\nbiomarkers for accurate risk stratification. Notably, in postmenopausal patients, persistent solid lesions\ngenerally warrant surgical excision, which provides both therapeutic resolution and definitive diagnostic\nconfirmation via histopathology--the gold standard for these tumors--while mitigating potentially life-\nthreatening complications. This case underscores the clinical imperative of maintaining a high index of\nsuspicion and implementing a systematic approach to ensure timely and safe management aligned with\ncurrent guidelines, without disregarding benign etiologies in clinical scenarios highly suggestive of\nmalignancy.\nAdditional Information\nAuthor Contributions\nAll authors have reviewed the final version to be published and agreed to be accountable for all aspects of the\nwork.\nConcept and design:\n  \nEmiliana Arcos-Ayala, Vanessa García-Gudiño\nAcquisition, analysis, or interpretation of data:\n  \nEmiliana Arcos-Ayala, Santiago Córdova-Egüéz, Fedra\nVela-Merino, Hugo Garzón-Ávila\nDrafting of the manuscript:\n  \nEmiliana Arcos-Ayala, Vanessa García-Gudiño\nCritical review of the manuscript for important intellectual content:\n  \nEmiliana Arcos-Ayala, Santiago\nCórdova-Egüéz, Fedra Vela-Merino, Hugo Garzón-Ávila, Vanessa García-Gudiño\nSupervision:\n  \nSantiago Córdova-Egüéz, Fedra Vela-Merino, Hugo Garzón-Ávila, Vanessa García-Gudiño\nDisclosures\nHuman subjects:\n Informed consent for treatment and open access publication was obtained or waived by all\nparticipants in this study. \nConflicts of interest:\n In compliance with the ICMJE uniform disclosure form, all\n \n2026 García-Gudiño et al. Cureus 18(10): e117684. DOI 10.7759/cureus.117684\n5\n of \n6\n\nauthors declare the following: \nPayment/services info:\n All authors have declared that no financial support\nwas received from any organization for the submitted work. \nFinancial relationships:\n All authors have\ndeclared that they have no financial relationships at present or within the previous three years with any\norganizations that might have an interest in the submitted work. \nOther relationships:\n All authors have\ndeclared that there are no other relationships or activities that could appear to have influenced the\nsubmitted work.\nReferences\n1\n. \nSharmila V, Saichandran S, Babu TA, Singh D: \nA rare case of bilateral ovarian fibroma presenting as Meigs\nsyndrome\n. J Obstet Gynaecol. 2013, 33:636-7. \n10.3109/01443615.2013.799128\n2\n. \nLazo-Pérez M, Pérez-Bell C, Pérez-García M, Donatién-Boris S, De Dios-Perera R: \nFibroma de ovario en una\ngestante joven\n. 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