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 [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 [4 ,5] .
Differential diagnosis of RLS includes tumors with fatty components such
as renal angioleiomyolipoma, adrenal myelolipoma, retroperitoneal
lipoma, and teratoma [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[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[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 [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 [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 [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[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 [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[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 [15] . Avoiding nephrectomy seems also
possible when the RLS is widely displacing the kidney [4,
16] . In addition to these criteria, the patient’s advanced age is
another argument for trying to preserve the kidney [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 [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 [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 [19] . At present the role of chemotherapy in the
management of RLS remains controversial [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 [5] .