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World Journal of Surgical Oncology
Open Access
Review
Myxoid liposarcoma: a rare soft-tissue tumor with a misleading
benign appearance
Francois Loubignac*1, Christophe Bourtoul2 and Francoise Chapel3
Address: 1Orthopaedic and traumatology Surgery "A", Font-Pré Hospital, Toulon, France, 2Visceralous Surgery, Font-Pré Hospital, Toulon, France
and 3Anatomopathology Department, Font-Pré Hospital, Toulon, France
Email: Francois Loubignac* - Francois.Loubignac@ch-toulon.fr; Christophe Bourtoul - Christophe.Bourtoul@ch-toulon.fr;
Francoise Chapel - Francoise.Chapel@ch-toulon.fr
* Corresponding author
Abstract
Background: Lipoma is by far the most common of all benign soft-tissue tumors which far
outnumber malignant tumors. Soft-tissue sarcomas are malignant tumors and are usually named for
the type of tissue in which they begin. Liposarcoma (LPS), which arises in the fatty tissue, is rather
an uncommon soft-tissue tumor. Multiple histologic subtypes of liposarcoma are recognized,
including myxoid liposarcoma, and correspond to tumors of very different prognosis. In two-third
of the cases, this tumor occurs in the muscle while often demonstrating a misleading benign
appearance as observed in the majority of soft-tissue sarcomas.
Case presentation: We report the case of a 50-year-old man operated on for a fat tumor of the
thigh initially diagnosed as lipoma but revealing to be a myxoid liposarcoma after histopathological
examination. The initial incomplete tumor excision required the need for a re-excision with
adjuvant chemotherapy and complementary radiotherapy.
Conclusion: When any suspicious soft-tissue tumor is diagnosed, the combined information
gathered from accurate preoperative radiographic planning and X-rays or surgical biopsy is of
tremendous value for establishing the most appropriate therapeutic program, highly adapted to the
histopathological findings.
Background
Lipomas account for 50% of all benign soft-tissue tumors.
Malignant tumors or sarcomas comprise approximately
1% of all soft-tissue tumors. They are also rare among the
malignant tumors that occur in adult, reporting a preva-
lence lower than 1% and an incidence of 30 cases per mil-
lion population [1,2]. Liposarcoma itself (LPS) comprises
about 15% of all soft-tissue sarcomas in the adult and its
prognosis is highly related to the location, and more par-
ticularly to the histologic pattern of the tumor [3-5]. This
fat tumor, of ubiquitous localization, commonly appears
as a slowly enlarging mass with a misleadingly benign
appearance [6]. However, any soft-tissue tumor requires
the need for a thorough preoperative X-Ray investigation
[1,7] and a biopsy should be performed if of more than
five centimeters diameter [2].
Case presentation
Mr A. Oma, a patient aged 50 years, with a 5-year history
of a small tumorous lesion, and regularly followed after a
polytraumatism, presents on 23 December 2003, with the
complaint of a gradually growing mass in his thigh for
Published: 22 April 2009
World Journal of Surgical Oncology 2009, 7:42 doi:10.1186/1477-7819-7-42
Received: 26 November 2008
Accepted: 22 April 2009
This article is available from: http://www.wjso.com/content/7/1/42
© 2009 Loubignac et al; licensee BioMed Central Ltd.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0),
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
World Journal of Surgical Oncology 2009, 7:42 http://www.wjso.com/content/7/1/42
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three months. This small tumor involving the antero-lat-
eral aspect of the thigh within the upper one-third, has a
soft consistency, no adherences to the surrounding struc-
tures and is well circumscribed. Neither functional nor
general symptoms are associated and routine blood tests
are normal. Such features suspects a common adipose
tumor of lipoma type and its excision is scheduled on 27
January 2004. This simple and rapid surgical procedure
includs the excision of an intramuscular, subaponeurosis
tumor, very well defined within the vast external of the
crural quadriceps. The tumor of approximately 8 cm is
sent to the laboratory of pathological anatomy. The
excised specimen is a 7.5-cm, well defined, flexible, ovoid
tumor of gelatinous aspect and brownish appearance,
with some more fleshy zones, without necrotic or hemor-
rhagic changes.
Histologic examination reveals a myxoid-type tumor,
consisting of an amorphous mucoid material, slightly
colored with small dark oval cells and no evidence of aty-
pia or mitotic figures (fig. 1A). An extensive capillary net-
work combined with the presence of some characteristic
lipoblastic cells confirms the diagnosis of liposarcoma
(fig. 1B). The tumor exhibits areas of variable cellular den-
sity; areas of dense proliferation of slightly atypical round
cells and rare mitotic figures (5 mitoses/10 fields × 40) are
detected (fig. 1C). The proportion of round cells is hardly
definable, and approximates 20%. The tumor is partially
encapsulated and situated less than one millimeter from
the margins of excision and is associated with some satel-
lite micro-nodules. The tumor is pathologically diagnosed
as myxoid/round-cell liposarcoma, of histoprognostic
grade 2 according to the National Union of Cancer Cent-
ers grading system (NUCCGS) (differentiation: grade 3,
mitotic index: grade 1 and necrosis: grade 0), and involves
the margins of resection [8,9]. A loco-regional assessment
of tumoral extension by MRI Scan of the thigh, and a gen-
eral assessment by thoracic and abdominal-CT-TAP-Scan
are performed and reveal negative. The oncology commit-
tee of the Paoli Calmette Institute of Marseille thus recom-
mends a re-excision procedure which is performed on
March 11th, 2004. All tissue potentially exposed to viable
tumor cells at the initial procedure have to be removed
during revision surgery including the surgical scar, the
path of the Jost-Redon drain, then, as a whole, the fascia
and deeper muscular structures on the entire height of the
initial tumor bed while performing a two centimeter-
wider margin of excision. The histopathology examina-
tion does not reveal any tumor residues at the site of
tumor bed excision.
Postoperative management is simple: from March to July
2004, the patient is treated with adjuvant chemotherapy
consisting of six cycles of MAID-type [Doxorubicine (20
mg/m2), Ifosfamide (2500 mg/m2), Dacarbazine (300
mg/m2) and Mesna (6000 mg)] combined with radiother-
apy delivering 50 Gy on the left thigh followed by 10 Gy
focused on the operating site.
In November 2004, the clinical and paraclinic post-thera-
peutic follow-up (MRI scan and CT-Scan) reveal normal
with minor orthopedic sequelas; a schedule of radio-clin-
ical follow-up is established (MRI Scan and TAP-CT-
Scan); the patient is in clinical remission at five years.
Discussion
Despite the misleading benign appearance of this malig-
nant tumor, complete preoperative X-Ray investigations
and biopsy should have been performed since any deep
tumor of soft tissues and/or which size exceeds five cen-
timeters is considered as being suspect and requires
biopsy prior to any excision procedure. Biopsy plays a cru-
cial role in accurate histopathological diagnosis, and
proper staging would enable the oncology committee to
implement the most appropriate therapeutic protocol [2].
The first biopsy must be guided by ultrasound or CT-Scan;
in case of failure, a surgical biopsy will be indicated and
performed through a suitable surgical approach to avoid
compromising the subsequent conservative management.
In the present case, the evidence of positive excision mar-
Photomicrograph 1A, 1B, 1C: histopathologic aspects of myxoid and round cell liposarcomaFigure 1
Photomicrograph 1A, 1B, 1C: histopathologic aspects of myxoid and round cell liposarcoma.
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gins increases the risk of tumor recurrence (around 60%)
in the absence of re-excision [2]. This resumption must be
scheduled from the results of a MRI Scan which looks for
potential tumor anatomical residue and should be per-
formed once proper healing of the initial surgery has been
achieved. The re-excision procedure takes place at the ini-
tial site of resection and is performed with a wider margin
of at least two centimeters of healthy tissue. All tissue
potentially exposed to viable tumor cells at the initial pro-
cedure should be removed at that time, including the sur-
gical scar and the orifices of drainage. A complementary
radiation therapy should be implemented on the operat-
ing site, with a minimal safety margin of five centimeters,
combined with adjuvant chemotherapy [10,11]. Lipomas
and liposarcomas are of adipose origin according to the
histogenetic classification of the World Health Organiza-
tion [8,9,12]. Soft-tissue sarcomas are malignant tumors
that originate in the soft tissues of the body which include
muscle, fat, fibrous tissue, blood vessels or peripheral
nerves.
The genesis of soft-tissue sarcomas has not yet been clearly
defined but several contributing factors that increase the
likelihood of developing these tumors have been identi-
fied: external radiation therapy and genetic factors are the
most well-established risk factors for soft tissue sarcomas.
Approximately 1% of patients treated with radiation ther-
apy for a malignant tumor, might develop, in previously
irradiated tissues, an osseous or soft tissue "radiation-
induced sarcoma", which may appear from three to ten
years later [10]. Some genetic diseases (neuromatosis,
retinoblastoma, L-Fraumeni syndrome) may lead to the
development of soft-tissue sarcomas. Lipoma is a very
common tumor, generally, of a small size (less than 5 cm)
and of superficial aspect whereas liposarcoma is a much
rarer tumor of large (more than 5 cm) deep-seated con-
nective tissue spaces, most commonly originating (three
out of four times) under the superficial fascia [1]. Three
main histological sub-types of LPS are recognized, which
differ in their morphological aspect and evolution: well-
differentiated LPS (the most frequent), Myxoid LPS
and\or with round cells (40% of the LPS), and the ana-
plastic LPS, a rarer category of bad prognosis [3,8].
Myxoid LPS and round-cell LPS represent the same entity
since they share a key genetic defect (t12; 16), (q13; p11).
This genetic abnormality results in fusion of the transcrip-
tion factor gene CHOP with FUS, and might be discovered
through specific techniques (RT-PCR or FISH) while play-
ing a critical role in the differential diagnosis [12,13].
Actually, the myxoid LPS may contain a variable number
of round cells which determines the degree of differentia-
tion and affects the prognosis [4]. There is still no consen-
sus on the percentage of round cells which would help in
the grading of such tumors; nevertheless, any myxoid LPS
containing more than 10% of round cells should conduct
to a cautious prognosis due to the risk of metastases occur-
rence [4,8]. The myxoid liposarcoma occurs predomi-
nantly at the level of the muscular chamber of the limbs
and more specifically in the thigh in more than 2/3 of the
cases; it rarely occurs in the retroperitoneum or the subcu-
taneous tissue.
It is often well defined with little adherence to the adja-
cent structures. The clinical diagnosis of malignancy of
this adipose tumor is thus difficult but findings of an
important size (> 5 cms) and rapidly growing mass should
alert and lead to the realization of an appropriate preop-
erative X-Ray investigation (U/S-Scan then MRI-Scan and
biopsy) [1,2,14]. The U/S-Scan helps determine the size,
the shape and the outlines of the expansive tissular proc-
ess as well as its ultrasound structure and its homogeneity
(fig. 2); it also determines its relationship with the sur-
rounding structures. Its deep location (subaponeurotic)
and\or the presence of a central necrosis are bad prognosis
factors requiring the need for a MRI Scan which still
remains the imaging modality of choice to best define an
adipose tumor of soft tissues, delineate its anatomical
location and carry out a proper pre-biopsy staging and a
well-planned surgical procedure (fig. 3A, B) [1,14]. The
LPS appears in spontaneous highsign in level-headedness
T1 which disappears in technique of fat suppression
(spectral saturation or "Fat Sat"); Myxoid liposarcoma is
suspected in the presence of cystic zones [1]. The tumour
can be badly limited, even infiltrative however a benign
intramuscular lipoma might be very infiltrative and a
well-circumscribed tumor does not eliminate a LPS [1,5].
Actually, a fat tumor should be considered as a liposar-
coma until proved otherwise when it features septums of
more than 2 mm thick and nodules or not fatty areas [14].
In case of suspected soft-tissue tumor, an accurate histo-
ultrasound aspect of a deep lipoma of the thighFigure 2
ultrasound aspect of a deep lipoma of the thigh.
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logical diagnosis should be performed prior to any surgi-
cal treatment which allows early carcinolytic excision in
case of malignancy. According to the standard surgical
procedure, a wide excision should be performed each time
the adjacent structures allow it (neurovascular axis).
Should the surrounding structures be unfavorable, neoad-
juvant chemotherapy and\or radiotherapy could be con-
sidered to reduce the tumor size [2,11,15]. A wide
excision is performed without seeing the tumor, with a
safety margin of at least 2 cm previously planned on the
MRI Scan, combined with drainage in the axis of the sur-
gical approach [2].
The operative specimen must be located and oriented, to
accurately define the margins of the excision. It is sent to
the pathologist, in a fresh state, along with a thorough
clinical information mandatory for proper histological
analysis (age, extent, location and depth of the tumor,
date of appearance, and previous treatment); the type and
objective of the surgical procedure are detailed [7]. The
myxoid LPS has a well-defined macroscopic aspect with
no signs of malignancy. The histological examination
reveals a myxoid tumor, of misleading benign appear-
ance, since it is free from cyto-nuclear atypias and demon-
strates a very low mitotic activity; the diagnosis is based
on the particular aspect of vascularization on the one
hand, and on the thorough detection of lipoblasts, on the
other hand, typically encountered in malignant tumors of
adipose origin [5]. Diagnosis of subaponeurotic tumors of
the thigh are easily performed in adults over 40 years old;
MRI: 3A, 3B: MRI-Scan of myxoid liposarcoma of the thigh, coronal (3A) and axial (3B) viewsFigure 3
MRI: 3A, 3B: MRI-Scan of myxoid liposarcoma of the thigh, coronal (3A) and axial (3B) views.
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Nevertheless, it is advisable to eliminate benign tumors of
myxoid aspect and more specifically intramuscular myxo-
mas and, in a post-traumatic context, lipomas presenting
myxoid degenerative changes or reactional tumor-like
lesions such as proliferating myositis [3,5,6]. The presence
of areas of round cell dense proliferation might result in
an uneasy differential diagnosis with other malignant
tumors (melanoma, carcinoma, lymphoma); the diagno-
sis is dependent upon accurate detection of lipoblasts,
possibly helped by immunohistochemical markers (S100
protein) [3,5]. There is a great variety of histopronostic
scoring systems; the National Union of Cancer Centers
grading system (NUCCGS) is widely used in Europe; it
was first described by Trojani and al.[9] then was revised
by Guillou and Coindre [8]. This rating system is based on
three histological criteria: differentiation, number of
mitoses and presence of a tumor necrosis. The prognostic
value of cytogenetic analysis determines the risk for local
recurrence which is first conditioned by the quality of the
surgical excision and, in a lesser measure, the histological
grading of the lesion. The analysis of the excision margins
is critical; excision margins that exceed one centimeter
might be considered as negative; margins under this value
are considered as " suspicious " or positive (intra-tumors)
[12]. The risk of metastasis and thus the global survival
rate mostly depend on the histological pattern [8,10]. In
the present case (histopronostic grade 2 featuring more
than 10% of round cells), the presence of a great number
of round cells is considered as the major predicting factor
for prognosis, and prevails over the histological grade, as
well as the presence of positive or negative excision mar-
gins. Myxoid LPS have a high risk of local recurrence
(50%) whereas pure myxoid LPS report a 20% rate of
metastasis. At the other extremity of the spectrum of dis-
ease, the LPS featuring a majority of round cells, metasta-
sizes in 70% of the cases. These metastases arise in lungs
and bone but, also, in serous membranes (pleura, pericar-
dium and peritoneum) [10]. The average survival rate is
80% at 5 years and 50% at 10 years, strongly determined
by the quality of the local excision [7,10]. The local refer-
ence treatment for soft-tissue sarcomas of the extremities
includes the combination of surgery and radiation ther-
apy. The indication should be discussed by a committee of
multidisciplinary oncologists; Surgery is usually com-
pleted by an adjuvant radiation therapy and, sometimes,
by a complementary chemotherapy according to the
results of the pathology examination and the general
extension of tumor [2,11]. Once the course of treatment
has been completed, a necessary schedule of follow-up
begins. Clinical examinations, imaging (MRI Scan and
TAP-Scan) are performed every six months for five years
after treatment, then annually for at least 5 years after this.
Since sarcomas are exceedingly rare tumors, our review of
the world literature provided very few studies on liposar-
comas and even less on myxoid LPS [3,7,10]; The pub-
lished series include all types of liposarcoma and soft-
tissue sarcomas, with a therapeutic protocol based on the
histological grade and potential metastases [2,7,10,15].
Despite the reassuring clinical aspect of his tumor, our
patient should have benefited from an X-ray investigation
and a preoperative biopsy. Moreover, his tumor was volu-
minous, deep and intramuscular. The histopathologic
examination of the operative specimen confirmed the
malignancy with positive margins of excision. Dujardin
[2] confirms that the isolated excision of a soft-tissue sar-
coma exposes the patient to a risk of local recurrence from
50 to 93% according to the type of tumour. The prognosis
for this patient is thus reserved since it presented with a
myxoid LPS which survival rate is 60% at 5 years [10]
which, furthermore, was initially handled by a margin
excision. Taking into account the tumor size (7.5 cm), the
histological features (number of round cells = 30%), the
initial margin excision and the young age of the patient
(50 years), re-excision followed by adjuvant radiation
therapy and implementation of a complementary chemo-
therapy was recommended by the oncology committee in
order to decrease the risk of local recurrence and metasta-
sis [2,7,10]. Staging studies comprising MRI Scan of the
thigh and an abdo-thoracic TAP-Scan, followed by a
tumor biopsy should have been undertaken for accurate
histological diagnosis. These elements would have helped
the oncology committee to suggest a wide surgical exci-
sion of the voluminous tumor completed by adjuvant
radiotherapy [9].
Conclusion
The present case clearly illustrates the problems associated
with the management of these rare tumors and which
might be encountered by any surgeon, whatever the surgi-
cal field. Any soft-tissue tumor diagnosed in the adult,
particularly when its size exceeds five centimeters and/or
when of subaponeurotic origin, typically requires the
need for a careful preoperative X-ray investigation com-
bined with a diagnostic biopsy. In case of malignancy, an
early accurate medico-surgical treatment should be imple-
mented, associated with a systematic histopathological
examination. The prognosis for patients with soft tissue
sarcoma largely depends on the quality and coherence of
the initial management protocol based on a close multi-
disciplinary cooperation within the oncology committee.
Competing interests
The authors declare that they have no competing interests.
Authors' contributions
FL prepared the draft manuscript. CB helped in prepara-
tion of the draft manuscript. FC contributed pathological
part of the manuscript and the photomicrographs. All
authors read and approved the final manuscript.
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Consent
Patients consent was obtained for the publication of this
case report.
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