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American Journal of  
Life Science and Innovation (AJLSI)

Retroperitoneal Müllerian Cyst Found Incidentally During Total Laparoscopic 
Hysterectomy: Is There a Role for MRI in Pre-Operative Evaluation?

Angela Nyambura Ngugi1*, Joseph Njagi1

Volume 3 Issue 1, Year 2024
ISSN: 2833-1397 (Online)

DOI: https://doi.org/10.54536/ajlsi.v3i1.2298
https://journals.e-palli.com/home/index.php/ajlsi

Article Information ABSTRACT

Received: April 04, 2024

Accepted: May 09, 2024

Published: May 14, 2024

Retroperitoneal cysts of  Müllerian origin are rare and often discovered incidentally during 
surgical procedures or imaging studies. We present a case of  a retroperitoneal cyst found 
during a total laparoscopic hysterectomy performed for myoma removal. A 40-year-old 
female presented with symptomatic myomas and underwent pre-operative evaluation, 
including pelvic ultrasound, which revealed no abnormalities apart from the myomas. A 
cyst was incidentally discovered in the retroperitoneal space during a total laparoscopic 
hysterectomy procedure. The cyst was excised and sent for histological examination, which 
confirmed its Müllerian origin. Retroperitoneal cysts of  Müllerian origin are rare findings 
during TLH. This case report highlights the importance of  thorough pre-operative evaluation 
and imaging studies and the significance of  intraoperative awareness in identifying incidental 
findings. Further research is warranted to determine the optimal diagnostic imaging strategies 
for such cysts.

Keywords
Retroperitoneal Cyst, Müllerian 
Cyst, Total Laparoscopic 
Hysterectomy, Leiomyoma, 
Incidental Finding

INTRODUCTION
Retroperitoneal cysts of  Müllerian origin are rare findings, 
often discovered incidentally during surgical procedures 
or imaging studies. These cysts arise from remnants of  
Müllerian duct remnants and can occur in various locations 
within the retroperitoneal space (Santana Gonzalez et 
al., 2021). Uterine fibroids, also known as leiomyomas, 
are benign tumors originating from the smooth muscle 
cells of  the uterus. Although up to 70% of  cases may be 
asymptomatic, they are sometimes associated with heavy 
menstrual bleeding, intermenstrual symptoms, pelvic 
pain, and pressure symptoms, necessitating treatment by 
medical therapies, interventional radiology, and surgical 
procedures (Giuliani et al., 2020). Total laparoscopic 
hysterectomy (TLH)  is a minimally invasive surgical 
procedure frequently performed to manage symptomatic 
fibroids. 
While uterine fibroids are a common indication for 
surgical intervention, the discovery of  an incidental 
retroperitoneal cyst during a TLH in a patient with uterine 
fibroids is a unique occurrence. Incidental findings during 
TLH can pose diagnostic challenges and require careful 
consideration. Although rare, retroperitoneal cysts of  
Müllerian origin have been reported in the literature 
(Yang et al., 2004). These cysts can present as an incidental 
discovery during surgery, often lacking pre-operative 
imaging clues (Rivas et al., 2022). Understanding such 
incidental findings’ characteristics, management, and 
implications is crucial for appropriate patient care.
This case report presents the incidental discovery 
of  a retroperitoneal cyst of  Müllerian origin during 
TLH performed in a patient with uterine fibroids. By 
highlighting this unique case, we aim to contribute to 

the existing literature and raise awareness about the 
importance of  thorough pre-operative imaging and 
management of  incidental retroperitoneal cyst findings 
during TLH.

LITERATURE REVIEW
Müllerian cysts are uncommon findings that often 
present as incidental discoveries during imaging studies 
or surgical procedures. These cysts arise from remnants 
of  the Müllerian duct system (Giuliani et al., 2020; Wilson 
& Bordoni, 2024). The Müllerian ducts, also known as 
paramesonephric ducts, are paired ducts that originate 
from the intermediate mesoderm in the embryo (Wilson 
& Bordoni, 2024). During early fetal development, 
these ducts emerge alongside the urogenital ridge and 
run laterally. They terminate at the Müllerian eminence 
within the primitive urogenital sinus. The Müllerian ducts 
play a crucial role in the development of  the female 
reproductive system (Sugi et al., 2021).  These paired 
structures emerge during early fetal life and contribute 
to the formation of  several female reproductive organs, 
including the fallopian tubes, uterus, cervix, and the upper 
two-thirds of  the vagina. In males, the Müllerian ducts 
typically regress due to the influence of  anti-Müllerian 
hormone (AMH) secreted by the developing testes 
(Wilson & Bordoni, 2024). However, remnants of  these 
ducts such as Müllerian cysts  may persist in both sexes, 
leading to various clinical conditions. Müllerian cysts 
result from focal incomplete regression of  the Müllerian 
ducts (Sugi et al., 2021). Areas where complete regression 
did not occur become localized cystic formations. These 
cysts can occur anywhere along the path of  Müllerian 
duct regression. Retroperitoneal Müllerian cysts are rare, 

1 P.C.E.A Tumutumu Hospital, Kenya
* Corresponding author’s e-mail: angiengugi75@gmail.com



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with limited prevalence data (Yang et al., 2004). They are 
typically discovered incidentally during imaging studies 
or surgery. The exact incidence remains uncertain due 
to their asymptomatic nature. When symptomatic, 
patients may experience Abdominal pain or discomfort 
due to cyst enlargement or pressure symptoms related 
to adjacent structures such as the urinary tract (Renzulli 
and Candinas, 2009). Imaging Modalities that can be used 
in the detection of  Mullerian cysts include Ultrasound,  
CT and MRI (Stefanopol et al., 2022; Yacoub et al., 2021; 
Yang et al., 2004). Ultrasound can visualize Müllerian 
cysts as hypoechoic lesions. However, ultrasound may 
not always provide detailed anatomical information 
compared to MRI. Ultrasound-guided aspiration can be 
performed for diagnostic purposes (Yacoub et al., 2021). 
On CT Scan Mullerian cysts may appear as well-defined 
hypoattenuating cystic masses. MRI however provides 
superior soft tissue characterization and multiplanar 
imaging capabilities for accurate pre-operative assessment. 
MRI characteristic features for Mullerian cysts include 
well-defined, unilocular cystic lesions, hypointense signal 
on T1-weighted images and hyperintense signal on T2-
weighted images (Renzulli & Candinas, 2009). Pelvic  MRI 
remains the imaging modality of  choice for diagnosing 
Müllerian cysts, allowing accurate assessment and guiding 
clinical management (Yacoub et al., 2021).
Treatment options for Müllerian cysts include observation 
and monitoring for asymptomatic cysts with regular 
follow-up imaging to exclude any other conditions (Johan 
et al., 2020). Surgical excision is indicated for symptomatic 
or large cysts. Pre-operative MRI guides surgical planning 
and should be carried out whenever possible (Johan 
et al., 2020). Complete cyst excision is usually the goal 
intraoperatively (Yacoub et al., 2021). Although rare, 
complications of  Müllerian cysts may include infection, 
hemorrhage, mass effect and transition to malignancy 
(Zhu et al., 2023).

METHODOLOGY
Case Presentation
A 40-year-old African female, Para 1+0, presented to 
PCEA Tumutumu Hospital in Nyeri, Kenya, with a 
ten-year history of  intermenstrual bleeding and heavy 

and prolonged periods associated with dysmenorrhea 
and intermittent lower abdominal pain radiating to 
the back. In 2013, she was diagnosed with uterine 
fibroids through a pelvic ultrasound scan and had been 
managed conservatively for her symptoms. However, 
she recently visited the gynaecology outpatient clinic 
with persistent lower abdominal pain and irregular 
periods. A repeat ultrasound scan revealed two intramural 
hypoechoic masses measuring 96.74x95.75x115.52 mm 
and 26.44x17.51x36.71 mm, respectively, along with 
a pedunculated fibroid in the left adnexal region. The 
decision was made to proceed with TLH.

Laboratory Investigation
The patient was admitted on 17th May 2023, and routine 
pre-operative tests were conducted, including full blood 
count, urea, electrolytes, creatinine, random blood sugar, 
and group crossmatch. The only abnormal findings were 
a microcytic anemia with Hb of  7.5 g/dl (Ref  11.5-16.5 
g/dl) and MCV of  67 fl (Ref  75-100 fl), due to chronic 
blood loss. Serum tumor marker tests were not carried 
out. 

RESULTS
The TLH procedure was performed under general 
anesthesia by consultant obstetrician/gynecologist 
and laparascopic surgeon Dr Njagi. Intraoperatively, 
the leiomyomas were noted to have fatty degeneration. 
After the removal of  the uterus, a retroperitoneal cyst of  
size 40mm by 5mm was incidentally noted (Figure 1A). 
Macroscopic examination revealed a white encapsulated 
lesion adherent to the left lower abdominal wall. The 
cystic lesion was filled with brownish fluid (Figure 1B). 
The lesion was surgically excised as a whole and sent for 
histopathological analysis. The whole surgical procedure 
took a total of  2 hours and 50 minutes with a total 
intraoperative blood loss of  about 50cc.
The post-operative stay was uneventful, with the patient 
experiencing mild pain. Vitals remained stable, and a 
physical examination indicated normal bowel sounds. 
Post-operative medication consisted of  Paracetamol 
1g IV TDS for 3 days and Ceftriaxone 1g IV twice 
daily (BD) for 3 days. Upon discharge, the patient was 

A B

Figure 1: A retroperitoneal cyst of  size 40mm by 5mm was incidentally noted (A).  The cystic lesion was filled with 
brownish fluid



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Figure 2: Histopathological analysis of  the excised retroperitoneal cyst showed a thick-walled multilocular cyst lined 
by benign ciliated epithelium

prescribed oral Metronidazole 400mg TDS, Cefuroxime 
500mg BD, Aclosara SP (Aceclofenac/Paracetamol and 
Serratiopeptidase 100mg/325mg/15mg, Sara Remedies) 
PO TDS for 5 days, and IFAS (Iron and Folic Acid) 2 tabs 
PO BD for 1 month.
Histopathological analysis of  the excised retroperitoneal 
cyst showed a thick-walled multilocular cyst lined by 
benign ciliated epithelium (Figure 2). Adjacent reactive 
nodes were noted attached to the external wall. The 
features were consistent with a cyst of  Müllerian origin, 
further supporting the incidental finding during TLH. 
The cyst wall consisted of  a lining epithelium resembling 
the Müllerian epithelium, surrounded by fibrous tissue. 
No atypical cells or malignancy was identified. During 
a follow-up visit in the gynecology clinic scheduled two 
weeks post-surgery the patient had no complaints and 
the physical exam was unremarkable. The surgical wound 
was healing well. We explained the histology results to 
the patient.

DISCUSSION
The incidental discovery of  a retroperitoneal cyst of  
Müllerian origin during a TLH in a patient with uterine 
fibroids presents an intriguing case and raises several 
important considerations. Retroperitoneal cysts are often 
misdiagnosed pre-operatively (Johan et al., 2020). In our 
case, the patient presented with a history of  metrorrhagia, 
dysmenorrhea, and lower abdominal pain radiating to 
the back. These symptoms, along with the presence 
of  uterine fibroids on ultrasound imaging, prompted 
further investigation and the decision to proceed with 
TLH. The intraoperative discovery of  a retroperitoneal 

cyst, unrelated to the uterine fibroids, highlights the 
importance of  appropriate pre-operative imaging and 
evaluation to detect such lesions early. Additionally, 
thorough exploration during surgical interventions is 
important, even in cases where the primary pathology is 
well-defined.
Pre-operative ultrasound imaging may not reliably detect 
retroperitoneal cysts of  Müllerian origin, as seen in 
our case where the cyst was not visualized on the pre-
operative ultrasound scan (Yacoub et al., 2021). Magnetic 
resonance imaging (MRI) provides a sophisticated 
method of  distinguishing mullerian anomalies from one 
another, characterizing the degree of  defect severity, and 
evaluating for concomitant urogenital anomalies non-
invasively and without radiation exposure, with superior 
soft-tissue delineation and availability of  advanced 
functional sequences (Udayakumar et al., 2023). MRI 
is also a commonly used tool for evaluation of  pelvic 
malignancies. Mullerian cysts may occasionally have 
malignant transformations that would only be picked 
by careful imaging using MRI, as has been shown by 
occasional case reports (Xiao et al., 2022; Zhu et al., 2023). 
Further studies may be done to determine the utility 
of  pre-operative MRI imaging in TLH to facilitate the 
identification of  pathology.
Histopathological analysis confirmed the cyst to be of  
Müllerian origin, characterized by a lining epithelium 
resembling the Müllerian epithelium, surrounded by 
fibrous tissue. The absence of  atypical cells or malignancy 
supported the benign nature of  the cyst. It is essential 
to differentiate retroperitoneal cysts of  Müllerian 
origin from other retroperitoneal cystic lesions, such as 



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lymphatic cysts or cystic teratomas, to guide appropriate 
management and prevent unnecessary interventions. The 
retroperitoneal cysts of  Müllerian origin are believed to 
be embryological remnants of  the Müllerian duct system 
(Santana Gonzalez et al., 2021). These remnants can give 
rise to various cystic structures in the retroperitoneal 
space, presenting a diagnostic challenge due to their rarity 
and diverse clinical presentations. 
Managing retroperitoneal cysts of  Müllerian origin 
largely depends on the clinical presentation, size, and 
symptoms associated with the cyst. Asymptomatic cysts 
can be managed conservatively with regular monitoring. 
However, in cases where the cyst is symptomatic, surgical 
excision is warranted (Renzulli and Candinas, 2009). The 
incidental discovery of  retroperitoneal cysts during TLH 
presents a unique opportunity for their complete removal, 
minimizing the risk of  future complications or recurrence 
(Stefanopol et al., 2022). The importance of  appropriate 
post-operative care, including pain management and 
prophylactic antibiotics, cannot be overstated to ensure 
optimal recovery.
This case report emphasizes the need for thorough pre-
operative evaluation and intraoperative vigilance during 
TLH. The incidental discovery of  retroperitoneal cysts of  
Müllerian origin during TLH highlights the importance 
of  considering these rare entities in the differential 
diagnosis of  retroperitoneal cystic lesions. Further 
research is warranted to explore the prevalence, clinical 
characteristics, and optimal management strategies for 
retroperitoneal cysts of  Müllerian origin, particularly 
when encountered during TLH. Enhanced awareness 
among clinicians and gynaecological surgeons regarding 
possible incidental findings during TLH can aid in early 
detection, appropriate management, and improved 
patient outcomes.

CONCLUSION
The incidental discovery of  a retroperitoneal cyst 
of  Müllerian origin during TLH in a patient with 
uterine fibroids highlights the diagnostic challenge and 
importance of  thorough intraoperative exploration. 
This case underscores the need for vigilance and 
consideration of  rare entities in the differential diagnosis 
of  retroperitoneal cystic lesions encountered during 
TLH. Further research is necessary to advance our 
understanding of  retroperitoneal cysts of  Müllerian 
origin and optimize pre-operative detection using MRI.

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