27 year old female presenting with dysmenorrhoea and cyclical left iliac fossa pain.
Transvaginal ultrasound demonstrated a well-defined left adnexal lesion with the same echotexture as myometrium and vascularity in line with the remainder of the uterus. Centrally there was an avascular cavity with a thin echogenic rim and fluid content showing homogeneous low-level echoes. The endometrial cavity was normal, with two cornua demonstrated, and both ovaries were identified separately and showed a normal morphology.
The patient went on to MRI to further evaluate the lesion, which again showed a cavitated left sided mass. The mass lay at the site of round ligament insertion and showed a central cystic cavity with content showing T2-W shading, T1-W hyperintensity without signal loss on fat suppression and dependent layering. The endometrial cavity had a normal configuration with two cornua identified. Both ovaries were normal. Remainder of the myometrium was normal with no adenomyosis or fibroids.
Accessory and cavitated uterine malformations (ACUMs) are rare abnormalities of the uterus which are almost exclusively seen in young women (≤ 30 years). Until c.2012 were termed ‘Juvenile Cystic Adenomyomas’ (JCA) but are now considered to be a rare Müllerian duct anomaly and thought to arise from duplication of the Müllerian duct at the level of attachment of the round ligament [1,2].
ACUMs are often referred to as ‘uterus-like’ masses as they have functional endometrium surrounded by a ‘myometrial mantle’ of irregularly arranged smooth muscle cells. There is no communication between the endometrial cavity and cavity of the ACUM.
ACUMs are an underdiagnosed cause of dysmenorrhoea, pelvic pain and infertility. Patients typically present with dysmenorrhoea and/or severe pelvic pain, often ipsilateral to the lesion. The pain is often progressive from the time of menarche and persists during the menstrual cycle. Pain is generally described as refractory to conservative management including non-steroidal anti-inflammatory drugs, the oral contraceptive pill or a combination of both.
Diagnostic criteria :
Imaging modalities :
Ultrasound (preferably transvaginal): Well-defined adnexal lesion at the expected location of the round ligament with the same echotexture as myometrium, showing vascularity on Doppler imaging in line with the rest of myometrium, and a central avascular cavity containing hyperechoic fluid that can show dependent layering (similar appearance to endometrioma content). The uterus is otherwise normal in appearance
MRI: Well-defined, cavitated mass in the myometrium at the expected ipsilateral round ligament insertion site. Normal T2 hyperintense endometrial lining and haemorrhagic content within (T1-W hyperintensity without signal loss on fat suppression and T2-W hypointense shading. The endometrial cavity is normal in appearance with normal bilateral cornua, no adenomyosis and no communication between the endometrial cavity and the cavitated lesion in the myometrium.
Most commonly managed with curative resection which can be performed lapraoscopically or open and helps preserve fertility [4,5,6].
Can be managed conservatively with hormonal treatment.
 Acién P, Acién M, Fernández F, et al. (2010) The cavitated accessory uterine mass: A Müllerian anomaly in women with an otherwise normal uterus. Obstet Gynecol 116: 1101-1109 (PMID: 20966695)
 Acién P, Bataller A, Fernández F, et al. (2017) New cases of accessory and cavitated uterine masses (ACUM): A significant cause of severe dysmenorrhoea and recurrent pelvic pain in young women. Human Reprod 27: 683-694 (PMID: 22252088)
 Naftalin J, Bean E, Saridogan E, et al. (2021) Imaging of gynaecological disease (21): clinical and ultrasound characteristics of accessory cavitated uterine malformations. Ultrasound Obstet Gynecol 57:821-828 (PMID: 32770812)
 Paul PG, Chopade G, Das T, et al. (2015) Accessory Cavitated Uterine Mass: A rare cause of severe dysmenorrhea in young women. J Minim Invasive Gynecol 22:1300-1303 (PMID: 2609318)
 Park JC and Kim DJ. (2020) Successful laparoscopic surgery of accessory cavitated uterine mass in young women with severe dysmenorrhea. Yeungnam Univ J Med. doi: 10.12701/yujm.2020.00696 (PMID: 32942350)
 Peyron N, Jacquemier E, Charlot M, et al. (2019) Accessory cavitated uterine mass: MRI features and surgical correlations of a rare but under-recognised entity. Eur Radiol 29: 1144-1152 (PMID: 30159623)
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