Accessory Cavitated Uterine Malformation Presenting as Acute Abdomen with Ipsilateral Ovarian Torsion: A Surgicopathological Surprise.

An 11-year-old female child, 3 months postmenarche with cyclical dysmenorrhea presented with 1 week of abdominal pain and intermittent nonbilious emesis, followed by 24 h of worsening pain and fever. Examination revealed tachycardia, suprapubic tenderness. On per rectal examination, a fixed, tender 3 cm × 2 cm ovoid mass anterior to the rectum was felt. She was managed conservatively initially elsewhere and referred with plain computed tomography of the abdomen, suggesting features of suspicious tuboovarian abscess with ovarian torsion/a complex tubo-ovarian mass without calcification [ Figure 1 ]. Plain computed tomography - Axial film of pelvis showing bladder with adnexal mass and free fluid. CT: Computed tomography. (a) Adnoxal mass, (b) Bladder, (c) free fluid U-Uterus Routine blood investigations showed leukocytosis with normal serum AFP and βhCG.[ 2 ] Emergency diagnostic laparoscopy [ Figure 2a ] demonstrated a 3–4 cm ovoid, fleshy mass just inferior to the round ligament with hemorrhagic free fluid and a gangrenous left ovary, necessitating conversion to Pfannenstiel laparotomy, left salpingo-oophorectomy, and en bloc excision of the adjacent mass was done [ Figure 2b ]. Yellow arrow - Accessory cavitated uterine malformation (ACUM) (a) Laparoscopic view showing adnexal mass (yellow arrow) with hemorrhagic free fluid (green arrow). (b) Specimen showing ACUM (yellow arrow) with gangrenous ovary and fallopian tube. (c) Gross specimen showing cavitated mass (d and e). Histopathology examination showing myometrial mantle and viable endometrium in ACUM, showing myometrial mantle with endometrium The pathology team urgently alerted that the excised “adnexal mass” exhibited uterine-type myometrium with a cavitating endometrium and chocolate brown content, raising alarm of potential inadvertent uterine removal in the emergency setting. Rapid, targeted postoperative pelvic ultrasonography immediately confirmed an intact native uterus with a healthy contralateral adnexa-clinching ACUM. Histopathology revealed an endometrium-lined cavity with glands and stroma surrounded by concentrically arranged smooth muscle consistent with a myometrial mantle, meeting pathologic criteria for ACUM when correlated with the lesion’s location and a normal eutopic uterus [ Figure 2c - e ].[ 3 ] The child is followed up for 2 years postsurgery, she is having regular cycles, no further dysmenorrhea.

Accessory cavitated uterine malformation (ACUM) is a distinctive Müllerian anomaly characterized by a solitary, cavitated, myometrial mass containing functional endometrium and typically located along the course of the round ligament, without communication with the uterine cavity or fallopian tube.[ 1 ] Although historically labeled juvenile cystic adenomyoma or uterine-like masses, Acien et al .[ 2 ] consolidated the entity under the term ACUM in 2012. Fertility impact and rare malignant transformation have been described, supporting complete excision when feasible.

In perimenarcheal adolescents with lateralized cyclical pain and a para-uterine, round-ligament–adjacent mass, ACUM should be prioritized in the differential, and immediate imaging pathology reconciliation can transform a surgical pathological surprise into precise, fertility-preserving care with curative excision of the accessory mass. This is the youngest and first case to be reported as ACUM presenting with ovarian torsion in the literature. The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. There are no conflicts of interest.

ACUM is a cavitated, endometrium-lined, myometrium-walled lesion situated beneath the round ligament in continuity with the anterolateral uterine wall but without communication to the uterine cavity or tube. The prevailing theory implicates gubernaculum dysfunction in embryogenesis, resulting in duplication/persistence of Müllerian tissue at the round ligament attachment, producing an accessory, functional uterus-like structure. Ultrasound and magnetic resonance imaging (MRI) provide pathognomonic clues for preoperative identification in adolescents with severe dysmenorrhea. Ultrasound often shows a myometrium-like ovoid lesion along the round ligament with internal hemorrhagic echoes and intrinsic vascularity, normal B/L uterine cornua and ovaries with absence of diffuse adenomyosis.[ 3 ] MRI demonstrates a T1 bright hemorrhagic cavity with T2 shading and a low T2 myometrial rim separate from a normal uterine cavity, thereby differentiating ACUM from ovarian or uterine mimics in practice. Noncommunicating rudimentary horn (Robert’s uterus):[ 5 ] Uterus didelphys results from complete failure of Müllerian duct fusion, producing two separate uterine cavities (often with duplicated cervices ± vagina), each communicating with its respective tube, whereas ACUM has a normally shaped functional true uterus. Juvenile cystic adenomyoma: intramyometrial hemorrhagic cyst near the junctional zone within the uterine wall, whereas ACUM is eccentric/para-uterine with a distinct myometrial mantle and uterus-like organization outside the eutopic cavity in young patients Endometrioma: ovarian ground-glass cyst with ovarian cortex continuity, unlike ACUM’s myometrium-walled para-uterine lesion without ovarian tissue in the wall on imaging correlation in adolescents Degenerating fibroid with cystic change: Fibroids lack functional endometrial lining; MRI shows low T2-signal myometrium-like whorled mass with cystic degeneration but no T1-bright hemorrhagic cavity surrounded by endometrium Tubo-ovarian abscess: septate inflammatory mass with purulence and systemic sepsis that may mimic adnexal masses on imaging. Noncommunicating rudimentary horn (Robert’s uterus):[ 5 ] Uterus didelphys results from complete failure of Müllerian duct fusion, producing two separate uterine cavities (often with duplicated cervices ± vagina), each communicating with its respective tube, whereas ACUM has a normally shaped functional true uterus. Juvenile cystic adenomyoma: intramyometrial hemorrhagic cyst near the junctional zone within the uterine wall, whereas ACUM is eccentric/para-uterine with a distinct myometrial mantle and uterus-like organization outside the eutopic cavity in young patients Endometrioma: ovarian ground-glass cyst with ovarian cortex continuity, unlike ACUM’s myometrium-walled para-uterine lesion without ovarian tissue in the wall on imaging correlation in adolescents Degenerating fibroid with cystic change: Fibroids lack functional endometrial lining; MRI shows low T2-signal myometrium-like whorled mass with cystic degeneration but no T1-bright hemorrhagic cavity surrounded by endometrium Tubo-ovarian abscess: septate inflammatory mass with purulence and systemic sepsis that may mimic adnexal masses on imaging. Definitive therapy is complete excision of the accessory cavitated mass with preservation of a normal uterus and any viable adnexa, with reported series documenting high rates of pain relief and encouraging reproductive potential after surgery in this typically young cohort. A 2023 case series plus literature review collated 88 patients (mean age 21.9 years; range 14–39), showing consistent lateralization near the round-ligament insertion, MRI as the preferred modality, and symptom improvement in most following surgical excision, underscoring the entity’s predilection for young patients.[ 2 ] Adolescent-focused case series and reports highlight underdiagnosis in teens with severe dysmenorrhea and demonstrate straightforward laparoscopic cure when the lesion is recognized.[ 5 ]