Giant neoplastic omental cyst masquerading as ascites: a case report.

Abstract

Cystic lesion of the omentum and mesentery are rare. The incidence of both cyst types has been variously reported to vary from 1/27,000-100,000 hospital admission. Omental cysts occur three to ten times less frequently than mesenteric cyst. Preoperative diagnosis is infrequently made because of lack of characteristic symptoms and signs.
We present our diagnostic and management challenges in a 43-year-old man with an unusually giant omental cyst confirmed as fibrosarcoma at histology. The cyst gave the abdomen an anteroposterior diameter of about 74 cm that could not be penetrated sufficiently by X-ray photons to produce diagnostic image even at maximum attainable output. Patient benefited from surgical excision. The removed cyst contained about 35 litres of fluid.
Neglected omental cysts as in this case may grow to enormous size, undergo malignant transformation and poses serious diagnostic and surgical challenges.

Full text

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Case report
Giant neoplastic omental cyst masquerading as ascites: a case report
Ganiyu A Rahman1*, Adekunle Y Abdulkadir2, Samuel A Olatoke1,
Stanley Uwaezuoke1, Ibrahim F Yusuf1and Kolawole T Braimoh2
Open Access
Addresses:1Department of Surgery, Division of General Surgery, University of Ilorin Teaching Hospital, Ilorin, Nigeria
2Department of Radiology, University of Ilorin Teaching Hospital, Ilorin, Nigeria
Email: GAR* - garahman1@yahoo.com; AYA - akyisau@yahoo.com; SAO - samuelolatoke@yahoo.co.uk; SU - uwastan@yahoo.com;
IFY - funsho_65@yahoo.com; KTB - wolebraimoh@yahoo.com
*Corresponding author
Received: 8 August 2009Accepted: 28 August 2009Published: 16 September 2009
Cases Journal 2009, 2:6482doi: 10.4076/1757-1626-2-6482
This article is available from: http://casesjournal.com/casesjournal/article/view/6482
© 2009 Rahman et al.; licensee Cases Network Ltd.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0),
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
Introduction: Cystic lesion of the omentum and mesentery are rare. The incidence of both cyst
types has been variously reported to vary from 1/27,000-100,000 hospital admission. Omental cysts
occur three to ten times less frequently than mesenteric cyst. Preoperative diagnosis is infrequently
made because of lack of characteristic symptoms and signs.
Case presentation: We present our diagnostic and management challenges in a 43-year-old man
with an unusually giant omental cyst confirmed as fibrosarcoma at histology. The cyst gave the
abdomen an anteroposterior diameter of about 74 cm that could not be penetrated sufficiently by
X-ray photons to produce diagnostic image even at maximum attainable output. Patient benefited
from surgical excision. The removed cyst contained about 35 litres of fluid.
Conclusion: Neglected omental cysts as in this case may grow to enormous size, undergo malignant
transformation and poses serious diagnostic and surgical challenges.
Introduction
Cystic lesion of the omentum, mesentery and retro-
peritoneum have been grouped together in the same
category by several authors because they are similar
embryologically and pathologically [1].
Though the first reported mesenteric cyst was ascribed
to Florentine anatomist Benevieni in 1507 [2], it was not
until 1852 when Gairdner described the first reported
omental cyst [2]. Omental cyst is less common than
mesenteric cyst.
The incidence of both cyst types has been variously
reported to vary from 1/27,000-100,000 hospital admis-
sion [3]. A high index of suspicion is required to make a
clinical diagnosis. Barr and Yamashita [4] stated that
“preoperative diagnoses are infrequently made because
they are not usually considered in the differential.”
We share our experience on the diagnostic and manage-
ment challenges in an adult with an unusually giant
omental cyst, found to be fibrosarcoma at histology in a
resource poor environment.
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Case presentation
A 43-year-old man, a Nigerian of Yoruba ethnicity,
presented with 6-year history of progressive abdominal
swelling associated pain, weight loss and weakness on
mild exertion. He had no facial or leg swelling, symptoms
suggestive of impaired renal function, jaundice, vomiting
and change in bowel habit.
He admitted to a recent history of early satiety. He had
attended five different hospitals and had various investi-
gations and treatments at different times for what was
thought to be ascites of chronic liver disease before
presenting at our centre. The rapid increase in the
abdominal swelling and the increasing difficulty/inability
to lie or sleeps in the supine position without dyspnoea a
month prior to presentation were of great concern to the
patient.
On examination, he was wasted, afebrile, anicteric,
dyspnoeic and had finger-clubbing grade II but without
other stigmata of chronic liver disease. He was well
oriented, conscious and alert, and had globally intact
cranial and motor functions.
Abdomen showed massive non-mobile cystic distension
(Figure 1) with positive fluid thrill but not shifting
dullness. Liver and spleen were difficult to assess, so was
balloting the kidneys. Hernia orifices, external genitalia
and digital rectal examination were normal. Clinical
differential diagnosis of omental cyst and mesenteric cyst
(Probably haemorrhagic cyst) was made.
The patient full blood count, liver function test, fasting
blood sugar, Hepatitis B surface antigen (HBs Ag),
urinalysis, PT and PTTK were normal. He has had Fine
needle aspiration of the liver for cytology in one of his
previous hospital visits and it was normal. Abdominal
ultrasonography showed intra thoracic displaced normal
sized liver with no focal intra-parenchymal lesion,
bilateral hydroureteronephrosis worse on the right and a
huge multiseptated cystic mass having some scattered
mobile bright internal echoes (presumed to be haemor-
rhages) and irregular solid components. There was neither
ascites nor lymphadenopathy. Sonographic impression of
mesenteric cyst or omental cyst with suspected malignant
transformation was made. Plain abdominal radiograph
attempted could not penetrate the mass for diagnostic
image even at maximum output attainable due to the
size of this mass having an anteroposterior diameter of
about 74 cm.
Patient was planned for exploratory laparatomy but he
defaulted to represent six months later in respiratory
distress, whence he was cachetic, could no longer lay
supine for a month, and anaemia had occurred
(PCV = 22%.). Ultrasonographic findings this time was
still similar to the former except for the increased and
aggregating internal echoes presumed to be blood clots.
Hence, an impression of haemorrhagic complex intra
abdominal cyst (?mesenteric, ?omental) with probable
malignant transformation was made.
He had two pints of blood transfused and emergency
exploratory laparatomy under general anaesthesia with
endotracheal intubation. Findings at surgery were huge
distended abdomen with dilated, tortuous vessels on the
anterior abdominal wall and on the parietal peritoneum,
huge omental cyst, containing about 35 litres of brownish
fluid, and some solid components with areas of necrosis.
The mass displaced the stomach and liver upwards, the
transverse colon inferiorly, spleen laterally to the left and
was adherent to the anterior abdominal wall. There was
minimal ascites. He had complete excision of the cyst,
which contained 35 litres of brownish fluid and weighed
37 kg (Figure 2).
Anaesthesia was maintained with 100% 02+ Halothane,
muscle paralysis with intravenous (IV) 100 mg suxametho-
nium for intubation then maintained with 6 mg bolus
pancuronium followed by intermittent IV 2 mg pancur-
onium. Halothane was discontinued intraoperatively
because of low blood pressure. Anaesthesia was reversed
with IV 1.2 mg atrophine and IV 25 mg Neostigmine.
Intraoperatively patient had 10 litres of 0.9% (isotonic)
Saline, 4 pints of blood and 10 mls of 10% calcium
gluconate. Urine output was 500 mls over the 2 hours that
surgery lasted. He was transferred to the intensive care unit
(ICU) for monitoring and elective mechanical ventilation.
While at the ICU, he had increasing abdominal distension
that yielded frank blood on abdominal tap.
Figure 1. A 43-year-old man with giant neoplastic omental
cyst: (A) preoperative photograph and (B) photograph
6 months after surgery.
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He was re-explored and about 1.2 litres of free intra-
peritoneal blood oozing from engorged parietal paritoneal
vessels was evacuated. There was no area of active visceral
bleeding seen. Haemostasis was secured with suture
ligation of the oozing parietal peritoneum vessels, through
and through apposition of the laxed anterior abdominal
wall with sutures and application of abdominal pack and
gauze on the anterior abdominal wall held with crepe
bandage for tamponade effect. Further 8 litres of isotonic
saline and 6 pints of fresh whole blood were given and
intravenous calcium gluconate was repeated. Post-opera-
tive analgesics and antibiotics were commenced. Vital
signs such as respiratory rate, pulse rate and blood pressure
improved considerably within 6 hours. He was extubated
16 hours post re-exploratory surgery and continued on
intranasal oxygen. By the second post-operative day, he
was stable enough and he was commenced on oral intake.
He was returned to the surgical ward on the third
postoperative day.
Histopathology of the removed specimen showed omen-
tal fibrosarcoma. Patient has been follow-up for 8 months
and he remains well (see postoperative photograph
6 month later in Figure 1B) and had no evidence of
recurrence.
Discussion
The term mesenteric and omental cysts are merely
descriptive topographic site and gross appearance These
lesions though uncommon, elicit interest because of their
unclear pathogenesis and confusing terminology [5].
Mesenteric cysts have been estimated to be three to ten
times more common than omental cysts [6]. However,
based on the numbers of reported cases, the ratio may be
set at 4.5:1 [6].
According to Conzo et al [7], mesenteric and omental cysts
are congenital abdominal lesions. However, most reported
cases as in this presentation occurred in adult, while only
about one third of cases are reported in children younger
than 15 years [8]. Probably, the benign nature of these
cysts, their generally asymptomatic nature unless when
complicated and the non-hindrance on patient day to day
activities makes affected patient not to present for medical
attention until gross abdominal swelling had set in. Thus,
neglected omental cysts as in our case may continue to
grow in size and even undergo malignant transformation.
Malignant change has been reported, but is uncommon.
Hardin and Hardy [3] reported that malignant trans-
formed omental cysts are usually of low-grade sarcomas
and carry a good prognosis if properly excised. Therefore, a
complete resection is mandatory because of the high
incidence of relapse [7].
Omental masses or cysts lack characteristic specific
symptoms and signs. Hence, diagnoses are often not
made untill the lesion has attained a size sufficient enough
to be palpable or cause compression on organs or
neighbouring structures. The diagnosis can therefore be
challenging and a high index of suspicion is required [8].
Omental cysts are usually differentiated from ascites by the
fact that it is not associated with flanks bulging during
recumbency since the cyst will follow as the patient moves.
This feature could not be elicited in our patient because of
the giant size of the mass at presentation.
Though plain abdominal radiograph and upper gastro-
intestinal series could be helpful in making diagnosis, the
imaging modality of choice is ultrasound [8]. Plain
abdominal radiograph was not helpful in our patient
due to the extreme size of thecyst that resulted in complete
attenuation of the X-ray photons even at maximum kilo
voltage attainable by our machine.
Ultrasonography in this patient revealed multiseptated
cyst having some solid components and features sugges-
tive of internal haemorrhage. The extensive nature of this
cyst hinders visualization of the pancreas. Thus, aside
operator dependency, giant omental cyst may impose
some ultrasonographic drawback. There were peculiar
limitations to CT Scan in this patient ranging from non-
ready availability, cost where available, the inability of this
patient to lie in supine position without respiratory
embarrassment, and above all the CT gantry will not
admit the patient based on our previous experience with
an abdominal mass that was not as giant as this case. We
Figure 2. Intra-operative photo showing the giant omental
cyst excised. This cyst contains about 35 litres of fluid and
weight 37 kg.
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are aware that CT would have efficiently delineated this
mass and its relationship to other intra abdominal
structures [5].
The goal of surgical therapy is complete excision of the
mass, which sometimes may require inclusion of the
adjacent structures [9]. However, in this patient complete
excision was achieved without resecting the adjacent
stomach or transverse colon.
The histological diagnosis showed omental fibrosarcoma.
Primary malignancies of the omentum are rare events but
they do occur [10]. In our patient, it is uncertain whether
the cyst was malignant ab initio or is a malignant
transformation in an omental cyst. The later is known to
occur in adult and it appears more probable in this case in
view of the prolong history of swelling and the sudden but
rapid increasing size of the swelling at later time.
The diagnosis in this patient was very challenging in view
of the limited resources. The patient responded well to
surgical intervention though he had a turbulent immedi-
ate postoperative period.
Conclusion
The management of this patient with giant omental cyst
was challenging but the patient benefited from surgical
excision though the immediate postoperative condition
was turbulent. Histology of the removed specimen
showed fibrosarcoma.
Consent
Written informed consent was obtained from the patient
for publication of this case report and accompanying
images. A copy of the written consent is available for
review by the Editor-in-Chief of this journal.
Competing interests
The authors declare that they have no competing interests.
Authors’ contributions
GAR, AYA participated in conception, design, literature
search, drafting, writing and review for intellectual
content. They also participated in the management of
the patient. SAO, IFY participated in the concept, manu-
script revision and patient information and management.
SU participated in patient information and management,
manuscript writing and revision. KTB participated in
patient management and manuscript revision. All authors
read and approve the final manuscript for publication.
References
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2.Gairdner WT: A remarkable cyst in the omentum. Transactions
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Barr WB, Yamashita T: Mesenteric Cysts. Am J Gastroenterol 1964,
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Ross PR, Olmsted WW, Moser RP, Dachman AH, Hjermstad BH,
Sobin LH: Mesenteric and Omental cyst: Histologic classifica-
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Saxena AK: Mesenteric and Omental cyst [http://emedicine.
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