In this clinical case, we wanted to contribute to the notification of the clinical case of retro-peritoneal liposarcoma, in doing so we participate in the understanding of this entity whose early management conditions the therapeutic success.

Through this clinical case, we highlight one of the most important indicators in the Malian health system; the delay in treatment.

If cancerous pathologies are detected early, treated early, this would significantly increase the survival of patients.

According to Rozan Marjiyeh [7] , in the retroperitoneal cavity, retroperitoneal liposarcoma (RPL) is the most common primary tumor and liposarcoma can occur in any region where fat is present, and about 30% of tumors occur in the retroperitoneal cavity; 35% come from perirenal fat which represents 40% of all retroperitoneal sarcoma tumors.

We think that, liposarcoma is an undervalued malignant tumor, sending it from the operating rooms to the anatomo-pathological examination would improve the notification of cases.

Shu Wang [8] , reported that primary retroperitoneal liposarcoma (PRPLS) occurs mainly in patients aged 60 - 70 years, without sexual predominance.

Chi Xu [9] , found that, liposarcoma usually occurs in the age groups of fifty and sixty years without a clear relationship with sex or race.

Our patient was male, 65 years old. The age group 50 and over would be a risk factor compared to other population groups.

Patients with primary LRP develop symptoms in advanced stages of the disease, mainly due to the mass effect on adjacent organs, and less frequently, by organ invasion [7] .

Our case had abdominal pain, vomiting, weight loss estimated at 8 kg, abdominal mass.

Rozan Marjiyeh [7] , showed in its literature review of 24 patients that, Abdominal computed tomography (CT) was the most commonly used radiological examination, performed for all patients, while abdominal ultrasound (US) and abdominal magnetic resonance imaging (MRI) was used as additional imaging for two patients. Preoperative diagnosis by a proven liposarcoma biopsy was available in four patients.

According to Shu Wang [8] , ultrasound, computed tomography and magnetic resonance imaging (MRI) are particularly important, as the first clinical signs of liposarcoma are not obvious.

Moreover, YI-XI WU [1] , in its study showed that at present, many immune markers are used to diagnose and identify diseases. However, it is not clear whether common markers of retro-peritoneal primary liposarcoma (PRPLS) (S-100, vimentin and Ki 67) are specific for different types of PRPLS.

Rozan Marjiyeh [7] reported that the amplification of MDM2 and CDK4 oncogenes is the standard for the diagnosis of well-differentiated liposarcoma and dedifferentiated liposarcoma; round myxoid/cell liposarcoma is characterized by the translocation of the FUS and DDIT3 genes, and pleomorphic liposarcoma is diagnosed by the presence of lipoblasts.

We performed an abdomino-pelvic scanner for our clinical case, the result was in favor of a tissue lesion process, calcified at the expense of the right peritoneal leaflets.

According to Rozan Marjiyeh [7] , liposarcoma is classified into 4 types: The anatomical distribution of liposarcoma subtypes depends on the histological type; while well differentiated and dedifferentiated subtypes are more common in the retroperitoneal cavity, pleomorphic and myxoid subtypes are more common in the extremities.

As for Adarsh Vijay [10] liposarcoma is classified into 5 types: Based on morphological characteristics and cytogenetic aberrations, liposarcomas are classified into 5 types. These are 1) well-differentiated liposarcoma (WDLPS); 2) dedifferentiated liposarcoma (DDLPS); 3) myxoid/round-cell liposarcoma (MLPS); 4) pleomorphic liposarcoma (PLPS); and 5) mixed liposarcoma. WDLPS is also classified into 3 subtypes: lipomatous, sclerotic and inflammatory Liposarcoma.

Complete resection is the gold standard for the treatment of this disease [9] .

Although the best treatment choice is a complete surgical resection, some tumors are not resectable at diagnosis due to distant metastasis or invasion of vital structures [9] .

In our case, we performed tumor decompression reduction of neighborhood organs.

The largest prospective monocentric study by Lewis et al. [11] suggested that the median survival of patients who underwent complete resection with markedly negative margins was 103 months, compared to 18 months for those who underwent incomplete resection.

The authors have different opinions about the benefit of radio-chemotherapy against liposarcoma.

For (YI-XI WU) [1] , chemotherapy and radiotherapy are ineffective for the majority of liposarcoma cases, with a 10% chemotherapy response rate.

Gunderson [12] found that radiotherapy, including preoperative, intraoperative and postoperative, can be used to treat liposarcoma to improve quality of life and tumor-free survival.

Banvalot et al. [13] showed limited benefit in some types, where neoadjuvant radiotherapy followed by surgery was superior to surgery alone.

Rates of local recurrence after five years, after complete resection are about 50% for well differentiated retroperitoneal liposarcomas and 80% for differentiated retroperitoneal liposarcomas, Adarsh Vijay [10] .

Rozan Marjiyeh) [7] in her study showed that tumor size was not a risk factor for recurrence. Larger tumors did not recur after R0 surgical resection, while smaller tumors did, as early as 3 months after resection. The tumour subtype (myxoid/mixed) and whether or not contiguous organs had been resected were risk factors for tumour recurrence.

Singer et al. [14] demonstrated that tumor histology type, tumor grade, and contiguous organ resection were significantly associated with tumor recurrence, while tumor size was not an independent risk factor.

Low-grade myxoids (<5% round cell component) and well-differentiated variants are about 90%. High-grade variants, such as pleomorphic, round cell (>5% round cell component), and dedifferentiated tumors, have 5-year survival rates of 30% to 50%, 60% and 75%, respectively [14] .