Adenomyois is the presence of endometrial tissue in the myometrium. The uterus has layers and normally, the endometrium and myometrium do not mix. In adenomyosis they do mix.
Uterine adenomyoma is a circumscribed nodular aggregate of benign endometrial glands surrounded by endometrial stroma with leiomyomatous smooth muscle bordering the endometrial stromal component. It may be located within the myometrium, or it may involve or originate in the endometrium and grow as a polyp (pubmed).
Four theories are proposed in the literature for the pathogenesis of extrauterine adenomyoma:
- the Müllerian duct fusion defect theory
- the sub-coelomic mesenchyme transformation theory
- the müllerianosis (developmentally misplaced Müllerian tissue) theory
- endometriosis with prominent smooth muscle hyperplasia or metaplasia
Extrauterine adenomyoma is considered extremely rare and it was first reported in 1986. So far there are only 14 cases of extrauterine adenomyomas reported in the English literature, most of them in the ovaries and 2 cases in the liver. The age ranged from 29-65 years of age, and the lesions had diameters of 0.4 cm to 10 cm.
Extrauterine adenomyoma of the liver has been reported twice so far. In 2013, a medical team from China reported the first case of extrauterine adenomyoma of the liver in a 29 year old patient. The patient presented with a 2 year history of low back pain, which became worse 2 months prior to seeing the doctor. The abdominal ultrasonography revealed a 3.6 × 2.5 cm hypoechoic solid mass arising from the posterior right lobe of the liver.
The patient had an exploratory laparotomy and the solid, firm mass was completely removed by liver tumor resection. Under the microscope the multilobular mass was composed of a smooth muscle component and benign endometrioid glands and stroma. The smooth muscle component was focally cellular, and the endometrioid glands had secretory features. Both the smooth muscle component and endometrioid tissue were positive for ER and PR.
In 2017 a team from the USA reported the 2nd case of extrauterine adenomyoma of the liver in a 50 year old patient and the 1st case associated with pelvic endometriosis. The patient presented with left lower quadrant abdominal pain. CT abdomen showed a complex, multiseptated 6.2×5.2×4.2 cm lesion in the inferior right hepatic lobe.
The liver biopsy performed at an outside hospital showed a benign smooth muscle tumor and a minor component of benign glands and stroma, resembling endometriosis/adenomyosis was identified. The patient subsequently underwent resection of the segment 6 of liver and the mass. Histological examination showed a mass composed of few endometrial glands and stroma surrounded by abundant smooth muscle.
A medical team from Turkey reported the first multiple abscessed adenomyomas forming uterus-like masses in the left and right broad ligament and in myometrium, in a 56 year old patient. The patient also had fibroids, adenomyosis, adhesions in the pelvis, and fluid in Douglas fossa. The authors mentioned that there are a few cases of abscessed endometriosis reported but only one of abscessed adenomyosis.
After 3 months of no periods, the patient had menorrhagia (heavy and prolonged bleeding) and pelvic and lumbar pain. The MRI showed a big mass closely related to the uterine corpus so it was thought to be originated from it. The patient had a laparotomy and 4 fibroids like masses were found in the right broad ligament and in other places. One of them was sent for frozen evaluation and based on the results a diagnosis of abscessed adenomyoma was made.
In 2005 a team from the University of Florida reported a uterine-like mass consistent with an extrauterine adenomyoma presenting 22 years following a total abdominal hysterectomy and bilateral salpingo-oophorectomy. The mass was pear-shaped with uterine-type smooth muscle and a cavity lined by functional endometrial glands and stroma.
The patient was a 50-year-old woman who presented with complaints of dysuria and suprapubic and pelvic pain. She was treated for 7 months prior to surgery for recurrent urinary tract infections.
The team mentioned that an understanding of the müllerian system suggests that either an embryologic malformation or a differential multipotentiality existing in the subcoelomic tissues in response to hormonal stimulation results in a supernumerary müllerian structure like a uterus, as observed in this case. The presence of endometrial glands and stroma in the mass confirms that the tissues in this mass are hormonally responsive. It is most likely that this uterine-like mass arose from the tissues of the secondary müllerian system in response to estrogenic stimulation.