Accessory and Cavitated Uterine Mass (ACUM) is a rare type of Mullerian anomaly usually seen in young women. It is an accessory and totally separate cavity covered by functional endometrium surrounded by myometrium-like smooth muscle cells; hence, it bears striking macroscopic and microscopic resemblance to the uterus. In comparison to the other Mullerian anomalies where the uterus is malformed, ACUM consists of abnormal placement of cavity in the uterine wall. This cavitated mass is confined to myometrium (different from diffuse adenomyosis), is encapsulated.
3 theories of ACUM development: widely accepted theory is congenital theory. Mullerian anomaly without uterine malformation caused by duplication and persistence of the ductal Mullerian tissue at the insertion of the round ligament, believed to be due to the gubernaculum dysfunction.
- congenital anomaly theory,
- heterotopias theory,
- metaplasia theory
- It is usually seen in young women <30 years.
- severe dysmenorrhea
- chronic recurrent pelvic pain in young females
The diagnostic criteria for ACUM are:
- an isolated accessory cavitated mass usually located just under round ligament;
- normal size uterus, fallopian tubes, and ovaries;
- an accessory cavity lined by endometrial glands and stroma;
- chocolate brown colored contents inside the mass;
- no evidence of adenomyosis in the uterus, although there could be tiny foci of adenomyosis in the myometrium of the accessory cavity due to increased intracystic pressure.
Diagnosis:
Ultrasonography (USG) and/or Magnetic Resonance Imaging (MRI) form the mainstay of diagnostic imaging. This condition is often under diagnosed due rarity of the condition and lack of awareness; therefore, a high level of suspicion combined with imaging can help in making an accurate diagnosis.
Laparoscopic excision of cavitated mass is the main stay of treatment.
