Accessory cavitated uterine mass (ACUM) as a miniature uterine anomaly causing severe lateralized dysmenorrhea: case series.

Objectives: Our study aimed to retrospectively analyse and present the clinical course of accessory cavitated uterine mass (ACUM), a rarely diagnosed uterine malformation.

Material and methods: The study group comprised 5 adolescents that were treated in the Division of Gynecology, Clinical Hospital of Obstetrics and Gynecology of Poznan University of Medical Sciences, between October 2017 and August 2022. Patients' age at diagnosis of ACUM ranged from 14.1 to 27.5 (mean 21.4) years. All patients complained of severe dysmenorrhea with significant lateralisation of the pain.

Results: Pelvic ultrasound (US) followed by pelvic magnetic resonance imaging (MRI) revealed the presence of a small cystic lesion surrounded by a ring of myometrium within or in connection with the regular uterine body. In four patients (80%), the lesion was on the right side, and in one patient (20%) on the left side. The volume of the ACUM cavity ranged from 0.04 to 2.4 (mean 0.8) cm³. Laparoscopic excision of ACUM, located near the uterine attachment of the round ligament, was performed in all five cases and resulted in the complete resolution of symptoms. None of the patients was diagnosed with adenomyosis or pelvic endometriosis.

Conclusions: ACUM is a small, surgically correctable cause of severe dysmenorrhea in young females with an otherwise normal uterus. The lateralisation of the menstrual pain should prompt the search for this malformation with imaging techniques (US, MRI). ACUM laparoscopic excision results in complete relief of symptoms. ACUM is not associated with pelvic endometriosis.