Retroperitoneal ‘uterus-like mass’ of cervical origin

Abstract

We report a rare case of a retroperitoneal uterus-like mass communicating with the endocervix, which presented as abdominal pain and bloating associated with severe irregular vaginal and postcoital bleeding. Our patient did not have any structural abnormalities of the urogenital system or otherwise, which makes a müllerian defect unlikely in our case. Based on the diagnostic criteria for the choristoma, that theory would be excluded here as the mass communicated with the endocervix. This strengthens the theory of metaplasia, under the effect of oestrogen and accelerated by the hyperoestrogenic state of pregnancy as the most likely postulate for our patient. Although the uterus-like mass is not commonly reported, it should be considered as a possible differential for pelvic masses.

Background

The uterus-like mass (ULM) is a lesion composed of a centrally lined cavity of endometrial mucosa surrounded by bundles of smooth muscle, bearing a striking resemblance to the uterus.¹ An entity with approximately 46 cases reported in English literature to date,^{2 3} most commonly reported in the ovaries.⁴ It has been reported in young, near menarcheal women⁵ to postmenopausal women post total abdominal hysterectomy and bilateral salpingo-oophorectomy (TAH and BSO). ⁶ and even occurring in men.^{7 8} ULMs have been associated with congenital anomalies^{1 5 9} and carcinomas.^{10 11} There is ongoing discussion regarding histogenesis of this entity.^{9 12–15}

Case presentation

We present this case of a 19 cm ULM arising from the uterine cervix extending into the retroperitoneal space, in a primiparous female in her 30s with unremarkable medical and surgical history. The patient was referred with abdominal pain, bloating as well as postcoital bleeding and a 3-month history of continuous vaginal bleeding with significant blood loss and passing of clots. This was associated with low haemoglobin and serum transferrin levels. To the best of our knowledge, this has been the only case of a retroperitoneal ULM of this size arising from the uterine cervix, with only one case previously reported to occur at this location.¹⁶

This mass was first identified as a 7.6×8.4×8.3 cm cervical fibroid on ultrasound examination during her pregnancy 2 years prior to the start of her symptoms (figure 1). The mass caused elongation of the cervix to measure 7 cm (figure 1) and the potential site for the lower segment caesarean section incision was thought be away from the mass (figure 2) and was recommended as a mode of delivery.

Figure 1.

A 7.6×8.4×8.3 cm mass arising from the posterior wall of the cervix at 35 weeks’ gestation.

Figure 2.

No fibroids present at the potential lower segment caesarean section site at 35 weeks’ gestation.

Investigations

On clinical examination, there was a large mass extending beyond the level of the umbilicus. The speculum vaginal examination showed normal vaginal epithelium with a pool of blood, and it was not possible to visualise her cervix. Bimanual examination demonstrated a well-circumscribed mass filling the whole pelvis with an extremely limited mobility.

Pelvic MRI detected a large midline lobulated pelvic mass with a central cystic area measuring 19.8×13.5×7.5 cm, arising from the lower uterus and pushing the uterine body high to the right side of abdomen resulting in a thin long stretched cervix. Internal haemorrhage was present centrally and some areas in the mass had ill-defined margins (figures 3–5). This corresponded with the previously discovered large fibroid from the cervix, however, it had shown an interval increase in size. The clinical impression was that of a large degenerated fibroid or a leiomyosarcoma.

Figure 3.

T2-weighted image. Sagittal view. 19 cm mass with cystic (white arrow) and solid elements (yellow arrow) present with internal haemorrhage/brown discharge centrally (blue arrow) communicating with the cervix.

Figure 4.

T2-weighted image. Axial view. Uterine body pushed high to the right side of abdomen (white arrow).

Figure 5.

T2 weighted image. Coronal view. Uterus-like mass arising from the cervix, pushing the uterus to the right side of the abdomen resulting in a very long and stretched cervix (yellow arrow).

Treatment

Since the patient wanted to retain her fertility, she went on to have excision of the mass via a midline laparotomy. She was found to have a large retroperitoneal mass extending in the left pelvic side wall. This mass was intimately attached to the ureter and the left pelvic vessels. Extensive retroperitoneal dissection revealed a communication of the mass with the left side of the endocervix. The mass was completely excised by performing lateral parametrial dissection and reflecting the bladder base and the left ureter. Part of the cervix was excised and reconstruction was undertaken to maintain the patency of the cervical canal. There was no evidence of pelvic endometriosis and both ovaries and fallopian tubes were normal.

Outcome and follow-up

Macroscopic examination revealed a lobulated, rubbery cream-coloured mass with a shiny surface. Microscopy identified a central cavity lined by endometrium with no evidence of malignancy. The findings were consistent with the diagnosis of a ULM (figure 6).

Figure 6.

H&E staining. Organoid pattern of smooth muscle with central cavity lined by endometrium (×10 magnification).

The postoperative course was uneventful, and the patient was discharged from the hospital on day 4 postoperatively.

At the time of preparing this manuscript, the patient is over 1-year postresection with no recurrence of symptoms.

Discussion

The ULM was first described by Cozzutto,¹ in which a mass with striking resemblance to the uterus had replaced the ovary of a 31-year-old woman. Since then, there have been approximately 45 reported cases of ULM’s, the majority—approximately 22% of all reported cases—occurring in the ovary. However, ULMs have also been found in other pelvic and extra pelvic locations: the ligaments of the ovary and uterus (broad ligament, ovarian ligament, uterosacral ligament) followed by the intestinal tract (small and large intestine) and its mesentery at approximately 15% and 13% of all reported cases, respectively. Occurring less commonly: in the uterus, mesosalpinx, cervix, vagina, pelvic floor, pelvic walls, peritoneum, omentum, appendix, liver, spinal cord and a lymph node.² Even developing in the scrotum, paratestis and bladder of men.⁸ Sizes of this mass have ranged from 2 cm to 36 cm² and have occurred in patients aged 9–67 years of age.^{5 11}

Abdominal pain is the most commonly occurring symptom, which is usually associated with dysmenorrhoea.² Other signs and symptoms reported include menorrhagia, amenorrhoea, bloating, epigastric pain, pelvic pain, a palpable abdominal mass and lower limb weakness, dependant on the location of the mass.2 3 8 17

There has been variable terminology used to describe the elusive mass in literature such as ‘ULM’,¹ ‘endomyometriosis’,¹³ ‘extrauterine adenomyoma’¹⁸ and ‘uterine adenomyoma with uterus-like features’.¹⁹ As symptomatology, gross features and ultrasonographic findings overlap with commoner pelvic pathologies, histological examination is, therefore, essential to diagnosis. MRI findings may also aid in narrowing the differential diagnosis.²⁰

While both ULMs and adenomyomas are composed of smooth muscle and endometrial tissue, ULMs differ by their structure which exhibits organ-like differentiation of a central cavity which is lined by endometrium surrounded by smooth muscle tissue, contrasted to the random scattering of endometrial tissue in islands within smooth muscle tissue that adenomyomas demonstrate.²

On MRI, typical features prevalent in the cases described in literature and in our case is an area that is isointense to endometrium; surrounded by a thicker outer layer that is isointense to myometrium on T1-weighted and T2-weighted sequences. Within the central cavity, there are cystic areas containing internal haemorrhage, appearing hyperintense on T1-weighted and T2-weighted sequences with extensive postcontrast enhancement which show no communication to the normal endometrial cavity.^{17 20–22}

The preliminary impression in our case was that this mass represented a degenerating fibroid, and while leiomyomas undergoing red degeneration show areas of haemorrhage, this appears as a peripheral rim of hyperintensity on T1-weighted image and not as numerous cavities of haemorrhage centrally as is the case with the ULM.²⁰

Three theories for the histogenesis of this entity have been suggested: metaplasia, congenital anomaly and heterotopia theory.

Cozzutto¹ reported the occurrence of a ULM in the ovary of a woman who had a 10-year history of ovarian endometriosis. The author suggested that the phenomenon was a result of ovarian stromal cell transition into metaplasia of smooth muscle cell during endometriosis. Furthermore, Rohlfing et al ¹³ proposed the term ‘endomyometriosis’ for this mass. Observations by Fukanga¹⁶ showed that smooth muscle metaplasia of ovarian endometriotic lesions is not uncommon and smooth muscle cells may originate from either metaplastic endometrial or metaplastic ovarian cells in the endometrial foci and rim respectively. To support this, there have been a number of cases of ULM occurring in women and men with endometriosis reported.8 13 16 23 24 Carvalho et al ²³ suggested that endomyometriosis and leiomyomatosis peritonealis disseminata may share the same histogenesis.

It has been postulated by Ahmed et al ¹⁴ that ULMs may be the result of transformation of the pluripotent subcoelomic tissues (of the secondary müllerian system) under the effect of oestrogen, and that these cells retain the potential to produce different müllerian structures such as the tubes or the uterus by differentiating into endometrial stromal cells, decidua or smooth muscle cells.⁶ Pai et al ⁴ demonstrated the link between raised Ca125 and the ULM, determining that the phenomenon is hormone dependant. Coelomic cells undergoing metaplasia have been found to have oestrogen and progesterone receptors²⁵ and ULMs have expressed an abundance of these receptors.2 3 26 27 This theory is supported by the presence of ULMs in patients without endometriosis or congenital anomalies, the presence of ULMs in multiple locations and the effectiveness of GnRH agonists in managing the disease.^{6 18} This is also the hypothesis for ULM cases in patients with prostate cancer using oestrogen therapy⁷ and females with breast cancer.⁴ González et al ⁸ reported a case of ULM in the inguinal area in a 52-year-old man, who was not on oestrogen therapy, however, had two right inguinal hernia repair procedures in the same location, possibly leading to a metaplastic process at the surgical site. Combined with a hyperoestrogenic state due pre-existing liver cirrhosis and the use of spironolactone—which has the ability to bind to oestrogen receptors and exhibit oestrogenic activity,²⁸ possibly leads to the formation of the mass.

ULMs do not fit any description of the uterine anomalies described in the classification by the American Fertility Society 1988.²⁹ However, they have been reported in men and women with defects of embryonic development of the urogenital tract.1 5 9 25 Rosai¹² proposed that the initial case described by Cozzutto¹ was due to either a true partial duplication of the müllerian system or a fusion defect. Furthermore, investigation into the first case revealed that the patient also had unilateral renal agenesis¹—a defect usually associated with unicornate uterus,³⁰ further strengthening Rosai’s hypothesis. Pueblitz-Peredo et al ⁹ reported another case of ULM associated with a renal anomaly—a double excretory system, and agreed that ULMs were due to uterine malformations. Defects in fusion of the müllerian ducts at different sites and lengths of the duct may demonstrate varying atresia’s or duplications of the uterus.

The theory of heterotopia was proposed by Peterson et al ¹⁵ in which he described a ULM of the ileum that could not be entirely explained by the aforementioned theories. Rougier et al ³¹ and Sharma et al ¹⁷ have described cases of ULM in the spinal cord of spina bifid patients, suggesting that heterotopic müllerian origin tissue within the neural tube may lead to a choristoma formation.

Batt³² described the term ‘müllerianosis’—an organoid structure of embryonically displaced tissue and proposed the diagnostic criteria for the choristoma: (1) the absence of pelvic endometriosis, (2) no connection with the endometrium, endocervix or endosalpinx and (3) no previous surgical intervention on the reproductive organs.

Bakhsi et al ²⁷ suggested that this rare phenomenon may also present as a late iatrogenic complication of morcellation hysterectomy. The author described the first case of a mesenteric ULM presenting 6 years postmorcellation hysterectomy, possibly a consequence of the implantation of fragmented remains.

ULMs are predominately benign lesions and surgery alone, has proven to be effective in the management of the disease several months to years postresection.^{3 16 27} However, malignant transformation to endometroid carcinoma and clear cell carcinoma has been reported in two cases.^{10 11}

Conclusion

We report a rare case of a retroperitoneal ULM communicating with the endocervix which presented as abdominal pain and bloating associated with severe irregular vaginal and postcoital bleeding. Our patient did not have any structural abnormalities of the urogenital system or otherwise, which makes a müllerian defect unlikely in our case. Based on the diagnostic criteria for the choristoma, that theory would be excluded here as the mass communicated with the endocervix. This strengthens the theory of metaplasia, under the effect of oestrogen and accelerated by the hyperoestrogenic state of pregnancy as the most likely postulate for our patient. Although the ULM is not commonly reported, it should be considered as a possible differential for pelvic masses.

Learning points.

• Aetiology of the uterus-like mass remains uncertain. Three main theories have been put forward for this condition: metaplasia, congenital anomaly and heterotopia.

• The symptoms of a uterus-like mass are varied and are location dependant. However, it most commonly presents as abdominal pain with associated dysmenorrhoea.

• Uterus-like masses are differentiated from commoner pelvic masses such as adenomyomas and leiomyomas by their organ-like differentiation. MRI may be useful in narrowing the differential diagnosis.

• The most common localisation of the uterus-like mass is the ovary—accounting for approximately 22% of the reported cases. Followed by the ligaments of the ovary and uterus and the intestinal tract and its mesentery, however, has been shown to affect all organs throughout the abdominal-pelvic cavity, as well as the spinal cord and lymph nodes in men and women.

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