Keywords
primary - retroperitoneal - serous - cystadenomas - cystic
Primary retroperitoneal serous cystadenoma (PRSC) is an extremely uncommon lesion
of retroperitoneum. Very few case reports of this entity have been described in the
literature. The pathogenesis is not well understood, although one of the proposed
hypotheses considers it to be an embryological remnant of the urogenital apparatus
with epithelial and mesothelial tissues.[1] These cysts oftentimes attain very large size before becoming symptomatic. Our case
review is focused on the diagnostic, therapeutic, and pathological findings of this
rare entity.
Case Presentation
A 79-year-old female presented to the emergency room with confusion, agitation, and
visual hallucinations after sustaining a fall. Although the patient was a poor historian,
her family members did not report prior history of abdominal complaints including
trauma, fever, weight loss, abdominal mass, or surgery. Abdominal examination revealed
soft, nontender, palpable fullness in the paraumbilical region. Gastroenterology service
was consulted for a nontender abdominal fullness on physical examination as well as
laboratory findings of severe iron deficiency anemia. The rest of her laboratory findings
were unremarkable.
A supine and upright abdominal film showed bowel loops displaced to the left with
a large amount of stool in the colon ([Fig. 1]). A noncontrast computed tomography (CT) of the abdomen and pelvis revealed a large
right retroperitoneal cystic structure measuring at least 26.6 × 11.7 × 16.7 cm. The
cyst was displacing the right kidney and right colon medially ([Figs. 2] and [3]). These findings were consistent with a giant retroperitoneal cyst (RPC). Though
her presenting complaints were attributed to her history of fall with possible concussion,
the diagnosis of RPC was found via thorough physical exam revealing a large, palpable
abdominal mass.
Fig. 1 Plain upright abdominal film showing displaced bowel loops to the left with large
amount of stool in the colon.
Fig. 2 Abdominal computed tomography shows a large right retroperitoneal cystic lesion with
displacement of the right kidney and bowel loops to the left.
Fig. 3 Abdominal computed tomography (sagittal plane) showing a giant retroperitoneal cyst.
The patient was taken to the operating room with a high suspicion that the CT findings
were consistent with a giant liver cyst. Upon entering the abdomen using a Hasson
technique and placing a 12-mm trocar, a diagnostic laparoscopy revealed a large cyst
with a blue hue. Given that the CT findings showed no evidence of nodularity, septation,
or intracystic masses and the laparoscopic findings were consistent, the suspicion
of malignancy was very low. Upon drainage of the cyst, it was clearly noted that it
was easily separable from the posterior liver and was in fact retroperitoneal in origin.
The posterior peritoneum was incised. The wall of the cyst was carefully dissected
from the anterolateral wall of the kidney, adrenal, and the posterior wall of the
ascending colon keeping in mind the significant distortions in anatomy secondary to
its size. A plane between the cyst and the posterior peritoneum was established, and
the cyst was separated using a combination of electrocautery and sharp dissection.
The cyst was then placed in an endocatch bag and removed through the 12-mm port. Thus,
the patient underwent a complete cyst excision using a laparoscopic transperitoneal
approach. Intraoperatively, the retroperitoneal location of the cyst was confirmed
as the cyst wall was separated from visceral peritoneum with ease ([Fig. 4]). Macroscopically, the cyst appeared to have thick walls and measured approximately
28 × 17 cm in size and containing 6 L of clear liquid ([Fig. 5]). Histopathology revealed a benign serous cystadenoma ([Fig. 6]). Should there have been a preoperative suspicion of malignancy based on imaging
or, diagnostic laparoscopy, an open approach with en bloc resection would have been
undertaken. A subsequent CT revealed interval removal of large RPC with properly repositioned
loops of bowel. The patient followed up in 3 months with no further surgical complications
or recurrence. We believe that the patient’s presenting symptoms were attributable
to her fall, concussion, and dehydration that resolved with hydration and supportive
therapy and not related to the findings of RPC or its surgical removal.
Fig. 4 Laparoscopic view of the cyst wall noted behind the posterior peritoneum.
Fig. 5 Macroscopic view of the surgical specimen shows thick cystic wall.
Fig. 6 Serous cystadenoma: fibrous tissue lined by mostly single-layer cuboidal or columnar
serous epithelium (arrows) with tubal metaplasia. There is no ovarian tissue or mucinous
epithelium. No cellular atypia (H & E x 100).
Discussion
The retroperitoneal space is bounded anteriorly by the posterior part of parietal
peritoneum, posteriorly by the psoas and quadratus lumborum muscles, as well as the
spine, superiorly by the diaphragm, and inferiorly by the muscular wall of the pelvis.[1] The large size of this space enables lesions to grow and remain asymptomatic for
a long period of time. Only those cysts derived from this space without direct contact
with other anatomical organs are included in the category of RPCs and are discussed
here. Retroperitoneal cystadenoma was first described by Staehlin in 1915.[2] Although primary retroperitoneal mucinous cystadenoma is more common, to our knowledge,
there are only a few cases of PRSC that have been described in the literature.[3]
[4]
[5]
[6]
[7]
[8] Sharatz et al reported the largest case of benign serous type cystadenoma measuring
18.7 × 15.4 × 10 cm[5]; our case is the largest reported PRSC in the literature.
Primary retroperitoneal cystic lesions are extremely rare because of a lack of epithelial
cells in this region. Their incidence is difficult to estimate. The pathogenesis of
primary RPCs is not well understood. Several hypotheses are described in the literature,
such as: (1) coelomic epithelial metaplasia,[9] (2) remnants of embryonal urogenital apparatus (pronephric, mesonephric, metanephric,
and Mullerian, depending on their cell line of origin),[10] (3) heterotopic ovarian tissue,[7] (4) germ cell layers (cystic teratomas),[11] and (5) enteric duplication cyst.[12] Based on their etiology RPCs can be further divided into traumatic (urinoma, hematoma),
parasitic, lymphatic, and cystic changes of a solid neoplasm (e.g., neurilemmoma,
paraganglioma, sarcoma). Based on their malignant potential, RPCs can be neoplastic
and nonneoplastic ([Table 1]).[13]
[14] Our literature review also reveals that based on their clinical course and microscopic
appearance, primary retroperitoneal epithelial lesions can be further classified into
benign (serous and mucinous cystadenoma), lesions with borderline malignancy,[3] and malignant (serous and mucinous cystadenocarcinoma).[15]
Table 1
Classification and characteristics of retroperitoneal cystic lesions
|
Type of lesion
|
Gender
|
Imaging appearance
|
Demographic features
|
|
Serous/mucinous cystadenoma[a]
|
Female
|
Homogeneous, unilocular, thin-walled cystic mass
|
Symptoms based on size, very low risk of recurrence with complete cyst excision, rarely
elevated CA125 and CA19-9 levels in the clear fluid[15]
[16]
|
|
Mullerian cyst[a]
|
Female
|
Unilocular or multilocular, thin walled with clear fluid
|
Obese patients, history of irregular menses, microscopically cyst wall has thick smooth
muscle and columnar epithelial cells
|
|
Cystic teratoma[a]
|
Both genders with little female predominance
|
Hypoattenuating fat within the cyst with sometimes typical wall calcifications
|
Mixed germline tissue on microscopy, young age, low malignant potential
|
|
Cystic lymphangioma[a]
|
Male
|
Large, elongated, multilocular, thin-walled, complex cystic mass, may cross into adjacent
compartment
|
Clear or milky fluid, single layer of endothelial cells with lymphoid aggregates
|
|
Cystic mesothelioma[a]
|
Female
|
Unilocular or multilocular thin- walled cyst
|
Not related to prior asbestos exposure, thin-walled cysts with watery fluid on pathology,
potential for local recurrence but no metastases
|
|
Tailgut cyst[a]
|
Female
|
Well-defined, multicystic mass with wide range of attenuation, thick walled if infected,
may compress rectum, rare thin calcifications
|
Embryonic hindgut in origin, occurs between rectum and sacrum. Microscopically, cyst
wall may show several different types of epithelium. Middle-aged women may be complicated
by infection and/or malignant transformation
|
|
Omental/mesenteric cyst[a]
|
Both genders
|
Thin or thick-walled, uni- or multilocular, anywhere from duodenum to the rectum
|
Bimodal age distribution (pediatrics and middle aged), small bowel mesentery origin
more common[20]
|
|
Epidermoid cyst[a]
|
Female
|
Thin-walled, unilocular with fluid attenuation, presacral retroperitoneal location
|
Ectodermal in origin, may occur anywhere, middle-aged women, may present with local
mass effect (e.g., pain, palpable mass). Microscopically has stratified squamous epithelium
with mixture of water, keratin, skin debris, cholesterol
|
|
Paraganglioma[a]
|
Slight female predominance
|
Homogenous, soft-tissue attenuation or central areas of low attenuation, rarely with
internal hemorrhage subsequently forming thick capsule mimicking cystic lesion
|
Arise from neural crest cells and sympathetic chain, may produce catecholamines and
lead to hypertension, middle-aged patient, autosomal dominant and may be associated
with MEN syndrome
|
|
Neurilemmoma[a]
|
Female
|
Thick-walled, located in paravertebral space or pelvic retroperitoneum
|
Encapsulated tumor from peripheral nerve sheaths (Schwann cells), 20–50 y of age,
may be associated with neurofibromatosis type-1
|
|
Urinoma[b]
|
Both genders
|
CT and MRI show water attenuated fluid collection, hypointense T1-weighted and hyperintense
T2-weighted images on MRI, IVP shows contrast extravasation into retroperitoneal tissues[16]
|
History of blunt trauma, usually located in perirenal space, usually has associated
hydronephrosis, percutaneous drainage is diagnostic and therapeutic
|
|
Hematoma[b]
|
Both genders
|
Unenhanced CT shows abnormal soft tissue density that may compress adjacent structures,
spiral CT better in assessing acute active bleed as it shows a jet of contrast extravasation[23]
|
History of trauma, coagulopathy, ruptured aortic aneurysm. Conservative management
in small, stable hematomas. Surgical management for large, unstable hematomas[23]
|
|
Pancreatic pseudocyst[b]
|
Both genders
|
Well-circumscribed, usually round or oval peripancreatic fluid collections of homogeneously
low attenuation that are usually surrounded by a well-defined enhancing wall[24]
|
Clinical history of pancreatitis, abdominal pain or palpable mass, elevated amylase
and lipase levels in blood test
Large symptomatic cysts require endoscopic, percutaneous or surgical drainage.
|
|
Nonpancreatic pseudocyst[b]
|
Both genders
|
Unilocular or multilocular fluid-filled complex cystic lesions with thick walls[18]
|
Rare lesions arising from mesentery and omentum.
May contain serous or purulent fluid with or without blood. Microscopically, cyst
wall lacks cell lining and consists of connective tissue with chronic inflammatory
changes[18]
[25]
|
|
Lymphocele[b]
|
Both genders
|
Unilocular or multilocular fluid-filled complex cystic lesions with thick walls[18]
|
Occurs in up to 30% of patients after lymphadenectomy and in 18% of patients after
renal transplantation. Symptoms mostly due to mass effect of adjacent structures or
secondary infection[25]
|
Abbreviations: CT, computed tomography; IVP, intravenous pyelogram; MEN, multiple
endocrine neoplasia; MRI, magnetic resonance imaging.
a Neoplastic.
b Nonneoplastic.
Clinical presentation of retroperitoneal cystic lesions may vary depending on their
location and size. Most commonly, cysts present as a palpable mass or abdominal pain.
Constitutional symptoms such as fever, changes in appetite, and weight loss may be
present especially in malignant lesions. Our patient had a palpable mass on examination,
leading to the further work-up and diagnosis.
There are no pathognomonic signs, symptoms, and laboratory or imaging findings reported
in the literature to confirm the diagnosis. However, few case reports suggest association
with elevated blood levels of carcinoembryonic antigen (CEA), fetoprotein, CA125,
CA19-9, and CA15-3.[6]
[8]
[15]
[16]
[17] There are also case reports that may suggest some diagnostic value of the presence
of CA125, CA19-9,[8] and CEA[15] in the aspirated cystic fluid. Certain imaging features that may suggest retroperitoneal
location include location of the lesion posterior to the psoas muscle, anterior displacement
of the rectum as well as anterior or medial displacement of major iliac vessels, ureter,
and the iliopsoas muscle. It is suggested that magnetic resonance imaging (MRI) is
a better modality than CT in identifying retroperitoneal lesions as it allows better
assessment of the presence or absence of enhancing internal septae and mural nodules,
and provides high quality internal signal intensity. The lesion’s local extent and
nonovarian origin is also better visualized on MRI.[18] Although cross-sectional imaging is very helpful in providing preoperative assessment,
most retroperitoneal lesions are defined during surgery. Macroscopically, the cyst
wall could be smooth, stratified, thin or thick, or fibrous, depending on their origin.
Additionally, the fluid could be clear, mucinous, or milky, depending on the etiology.
PRSC should be differentiated from other forms of cystic retroperitoneal lesions based
on history and microscopic appearance, as well as its malignant form cystadenocarcinoma
([Table 1]). Lee at al reviewed 56 cases of primary cystic mucinous neoplasms and reported
that the presence of solid nodules in the cyst was the only statistically significant
predictive factor of malignancy (cystadenocarcinoma).[19]
Diagnostic fluid aspiration is discouraged due to concerns of seeding during the procedure
if the lesion is malignant. The treatment of choice is complete surgical excision.
The type of surgical intervention depends on the location, size, and expertise of
the surgeon. Historically, laparotomy and complete cyst enucleation has been the recommended
treatment approach. However, laparoscopic cyst excision is becoming more popular in
recent years. Marsupialization and partial excision of the cysts or fluid drainage
are avoided given higher risks for recurrence as well as the need for repeat surgical
procedures. Obscure walls and location in close proximity of major blood vessels and
organs are the main challenges during RPC excision. Recurrence can occur in approximately
25% of cases of RPCs according to a case series.[20] In our case, we have used laparoscopic approach with complete cyst excision. In
cases of cystadenocarcinoma originating from the female reproductive organs, several
case reports suggest empiric total abdominal hysterectomy and bilateral salpingo-oophorectomy
with or without adjuvant chemotherapy.[21]
[22]
Conclusion
PRSCs are extremely rare lesions and oftentimes remain asymptomatic until they attain
a very large size. Although advances in CT and MRI techniques enable us to identify
various cystic lesions of the retroperitoneum, the exact diagnosis is based on histology
and requires high clinical suspicion as well as expertise. We believe that endoscopic
ultrasound may have a promising role in diagnosis, although further large prospective
studies are required to confirm that. All attempts should be made to completely remove
the cysts as risk of recurrence is high in partially excised lesions. Malignant lesions
should be treated more aggressively with radical surgery and chemotherapy. More research
is needed to better understand the pathogenesis of this entity.
