An uncommon cause of severe dysmenorrhea in a 16-year-old: accessory cavitated uterine mass

An uncommon cause of severe dysmenorrhea in a 16-year-old: accessory cavitated uterine mass DOI: https://doi.org/10.18203/2320-1770.ijrcog20260921Keywords: ACUM, Müllerian anomaly, Severe dysmenorrhea, Adolescent gynecology, Laparoscopic excisionAbstract Accessory cavitated uterine mass (ACUM) is a rare Müllerian anomaly characterized by the presence of an accessory cavity lined with functional endometrium within an otherwise normal uterus. It commonly presents in adolescents and young women with severe dysmenorrhea that is often resistant to medical therapy and may be misdiagnosed as adenomyosis or fibroid. We report the case of a 16-year-old girl presenting with severe cyclical dysmenorrhea for two years that was unresponsive to hormonal therapy. Ultrasonography revealed a focal lesion in the left lateral myometrium with a small cystic component, and magnetic resonance imaging demonstrated a well-defined thick‑walled cystic lesion with internal blood‑fluid level and no communication with the endometrial cavity, suggestive of ACUM. The patient underwent successful laparoscopic excision of the lesion. Intraoperatively, a cavitary mass containing thick chocolate‑coloured fluid was identified and excised, followed by uterine reconstruction. Histopathological examination confirmed a cavity lined by functional endometrium surrounded by smooth muscle. Postoperatively the patient experienced significant relief from dysmenorrhea. This case highlights the importance of considering ACUM in adolescents with severe dysmenorrhea unresponsive to conventional therapy and emphasizes the role of MRI and laparoscopic excision as both diagnostic and definitive treatment. Metrics References Peyron N, Rousset P, Charlot M, Devouassoux M, Raudrant D, Golfier F, et al. Accessory cavitated uterine mass: MRI features and surgical correlations of a rare but under‑recognised entity. Eur Radiol. 2018;29:1144‑52. DOI: https://doi.org/10.1007/s00330-018-5686-6 Oliver J. An accessory uterus distended with menstrual fluid enucleated from the substance of the right broad ligament. Lancet. 1912;179:1609. DOI: https://doi.org/10.1016/S0140-6736(00)51005-8 Acién P, Fernández F, Bataller A, Acién MI, Rodríguez JM, Mayol MJ. Accessory and cavitated uterine masses: a significant cause of severe dysmenorrhea. Hum Reprod. 2012;27:683‑94. DOI: https://doi.org/10.1093/humrep/der471 Goel A, Ibrahim D, Sharma R. Accessory cavitated uterine mass. Radiopaedia.org. Available at: https://radiopaedia.org/articles/accessory-and-cavitated-uterine-mass. Accessed on 12 January 2026. Zajączkowska W, Kapczuk K. Accessory cavitated uterine mass as a miniature uterine anomaly causing severe dysmenorrhea. Ginekologia Polska. 2023;12. DOI: https://doi.org/10.5603/GP.a2023.0060 Acién P, Acién M, Sánchez‑Ferrer ML. Complex malformations of the female genital tract. Hum Reprod. 2004;19:2377‑84. DOI: https://doi.org/10.1093/humrep/deh423 Shazly SA, Laughlin‑Tommaso SK, Breitkopf DM, et al. Diagnosis and treatment of uterine cystic adenomyosis. J Minim Invasive Gynecol. 2016;23:867‑876. DOI: https://doi.org/10.1016/j.jmig.2016.04.013 Takeuchi H, Kitade M, Kikuchi I, Kumakiri J, Kuroda K, Jinushi M. Diagnosis and laparoscopic management of juvenile cystic adenomyoma. J Minim Invasive Gynecol. 2010;17:716‑20. Chun JY, Kim TH, Kim SH. Accessory and cavitated uterine mass: MRI findings and laparoscopic treatment. Obstet Gynecol Sci. 2013;56:402‑5.