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\begin{document}

\title{A Giant retroperitoneal liposarcoma encasing entirely the right kidney:
A case report and a review of nephrectomy indications}



\author[1]{Houssem Harbi}%
\author[2]{Amira Akrout}%
\author[3]{Mohamed Fourati}%
\author[2]{Amine Zouari}%
\author[3]{Nozha Toumi}%
\affil[1]{Habib Bourguiba Hosp}%
\affil[2]{Habib Bourguiba Hospital}%
\affil[3]{University of Sfax Faculty of Medecine of Sfax}%


\vspace{-1em}



  
  \date{May 22, 2024}


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\selectlanguage{english}
\begin{abstract}
A 68-year-old female was operated for a giant dedifferentiated
retroperitoneal liposarcoma (RLS) encasing entirely the right kidney.
She had an en-bloc resection of the tumor with right nephrectomy. The
en-bloc resection should avoid R1 resection margins. Renal conservation
is suggested if the kidney is widely displaced and for elderly patient.%
\end{abstract}%



\sloppy


\textbf{Introduction:}

Fifteen percent of sarcomas are located in the retroperitoneal
space\textbf{{[}1{]}} . Liposarcoma is a rare malignant tumor that
originates from primitive mesenchymal cells rather than from mature
adipose tissue. It is the most common subtype of retroperitoneal
sarcomas\textbf{{[}2{]}} .

Retroperitoneal liposarcoma (RLS) may reach a very large size and may
cause tumoral infiltration of adjacent organs and large vessels before
being diagnosed. The average diameter of the tumor is 20 -- 25 cm with
an average weight of 15 to 20 Kg. The complete resection of the mass and
a favorable histopathologic grade are positively associated with
long-term disease-free survival \textbf{{[}2{]}.} However, preserving
neighboring structures, in particular the kidney, is actually
non-consensual and still challenging. Thus, nephrectomy should be
discussed case by case.

We report herein a case of a 68-year-old female with a giant
retroperitoneal liposarcoma arising from the right perirenal space.

\textbf{Case report:}

A 68-year-old female with no medical history presented with a complaint
of an abdominal painless mass. She has no associated urinary or
digestive signs (as nausea, vomiting, dyspepsia or constipation).
Physical examination showed a large hard non-mobile non-tender mass in
the right hemi abdomen and extending from the subhepatic region down to
the right pelvis. Laboratory findings and tumor markers were within the
normal range. Computed tomography showed a voluminous retroperitoneal
mass of 26 x 14 cm encasing entirely the right kidney (figure 1). It had
a mixed content, mainly of fat density and some microcalcifications. The
intestinal loops and other abdominal organs were displaced to the
midline without any signs of tumoral invasion. The Ct-scan didn't show
any liver or pulmonary metastasis.

The patient underwent a midline laparotomy: a bulky, well-encapsulated
mass was found arising from the right perinephric area and englobing
entirely the right kidney. The tumor measuring 20 x 30 x 15 cm was
totally excised en-bloc with the right kidney (figure 2). The radical
nephrectomy was necessary to achieve clear macroscopic resection margins
without any tumoral capsule break-in.

The patient had an uncomplicated postoperative course and was discharged
to home on the 6\textsuperscript{th} postoperative day.

Histological and immunohistochemistry analysis of the tumor revealed a
dedifferentiated RLS with no evidence of tumor invasion of the kidney.
Then, the patient had an adjuvant radiotherapy. After 18 months
follow-up, the patient has no clinical or radiological signs of disease
recurrence.

\textbf{Discussion:}

The RLS is a rare mesenchymal tumor representing 0.07\% to 0.2\% of all
neoplasia. This tumor mainly affects people aged 40 to 60 years and its
prevalence seems equivalent in both sexes \textbf{{[}3{]}} .

This tumor generally remains asymptomatic and can reach a large size
(over 30cm) with possible invasion or displacement of neighboring
organs. Indeed, the diagnosis is suggested when there is an abdominal
mass syndrome, a significant increase in abdominal volume or when there
are signs of digestive or urinary compression. This is explained by the
fact that the retroperitoneum is a large expandable space without any
bony boundaries \textbf{{[}4 ,5{]}} .

Differential diagnosis of RLS includes tumors with fatty components such
as renal angioleiomyolipoma, adrenal myelolipoma, retroperitoneal
lipoma, and teratoma \textbf{{[}1{]}} .

There are four histologic subtypes of liposarcoma: Undifferentiated,
pleomorphic, well-differentiated and myxoid. The undifferentiated and
pleomorphic types are associated to a high degree of
malignancy\textbf{{[}6{]}} .

Computed tomography (CT) is the most common used imaging method for the
diagnosis and preoperative evaluation of RLS. Indications for Magnetic
resonance imaging are Musculo-skelettal involvement or pelvic
extension\textbf{{[}6{]}} .

Surgery is currently the only potentially curative treatment. In fact,
complete surgical resection is the cornerstone of non-metastatic RLS
treatment. Furthermore, R0 resection is the most consistent prognostic
factor \textbf{{[}5{]}} .

It is usually technically challenging to achieve clear resection
margins. In most cases, it is necessary to proceed to an en-bloc
resection including one or more organs with the RLS \textbf{{[}7{]}} .
This means that surgeons tend to resect certain organs, especially the
kidney, in the case of giant RLS, to avoid difficult dissection and
mainly R1 resection margins \textbf{{[}5{]}} . For these reasons, our
patient had an en-bloc resection of the RLS with the right kidney.

The only definite indication for nephrectomy is kidney invasion or
perirenal fat infiltration. This should at best be suspected on
preoperative imaging and must be confirmed
intraoperatively\textbf{{[}8-10{]}} .

A RLS tumor that encases the kidney is a relative indication for
nephrectomy. In this case, kidney conservation may be attempted but
there is always a risk of incomplete resection \textbf{{[}11, 12{]}} .
Some authors reported an en-bloc resection of the RLS with kidney and
showed that there was no histologic tumoral involvement of the
kidney\textbf{{[}13, 14{]}} as was the case of our patient. This means
that nephrectomy could be avoided.

The absence of tumor (RLS) capsule break-in is a crucial condition for
kidney conservation \textbf{{[}15{]}} . Avoiding nephrectomy seems also
possible when the RLS is widely displacing the kidney \textbf{{[}4,
16{]}} . In addition to these criteria, the patient's advanced age is
another argument for trying to preserve the kidney \textbf{{[}11{]}} .

An ureter encasement is not a formal indication for nephrectomy. In
fact, a thorough dissection can be attempted with a prior insertion of a
double J catheter to reduce the risk of a possible ureteral injury.
Ureteral tumoral infiltration must lead to its resection with renal
auto-transplantation or to an ureterostomy \textbf{{[}4, 17, 18{]}.}

The long-term prognosis of RLS with incomplete resection (R1) is poor
with 5- and 10-years average survival rates at 16.7\% and 8\%
respectively \textbf{{[}5{]}} .

Metastatic and/or unresectable RLS (invading vital structures) have
obviously a very poor prognosis.

Neoadjuvant therapy could be an option to downstage the tumor before
surgical intervention. Patients with positive surgical margins or high
grade liposarcoma also need the consolidation from adjuvant therapy.
Studies have shown that radiotherapy reduces the risk of local
recurrence and improves the recurrence-free interval. However, data
supporting positive impact of radiotherapy on overall survival is
limited \textbf{{[}19{]}} . At present the role of chemotherapy in the
management of RLS remains controversial \textbf{{[}3{]}} .

Multidisciplinary cooperation is particularly important in the treatment
of giant retroperitoneal liposarcoma. Long-term follow-up CT scan is
important, especially within 2 years after initial resection, which is
peak recurrence period \textbf{{[}5{]}} .

\textbf{Conclusion:}

The RLS remains a rare tumor and should be suggested in cas of any large
retroperitoneal tumor. It is an aggressive tumor with no typical
presentation. The complete resection of the mass and a favorable
histopathologic grade are positively associated with long-term
disease-free survival\textbf{.} The complete (R0) surgical resection
needs frequently an en-bloc resection of the tumor with ipsilateral
involved or encased organs in particular the kidney. Criteria in favor
of renal conservation are well encapsulated RLS, widely displaced
kidney, well differentiated RLS sub-type and patient advanced age. An
entirely encased kidney and ureteral invasion are not formal indications
for associated nephrectomy.

\textbf{References:}

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\tightlist
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\textbf{Figure legends:}

\textbf{Figure 1:} Computed tomography (with medium contrast injection)
showing a giant retroperitoneal liposarcoma (blue star) encasing
entirely the right kidney that is also displaced widely to the midline

\textbf{Figure 2: Removed surgical specimen:} the retroperitoneal
liposarcoma was resected en-bloc with the right kidney (yellow star).\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/Image-1/Image-1}

\end{center}
\end{figure}\selectlanguage{english}
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\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/Image-2/Image-2}

\end{center}
\end{figure}

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