Thoughts and challenges of giant retroperitoneal liposarcoma: A case report

Abstract

BACKGROUND

Retroperitoneal liposarcoma (RPLS) is a rare malignant tumor initiated in adipocytes. It is discovered only when the tumor is large because of its deep anatomical location and insidious onset. Giant RPLS with a diameter exceeding 30 cm is extremely rare. Its diagnosis and treatment present extremely great challenges.

CASE SUMMARY

The patient, a 62-year-old woman, presented to the hospital complaining of abdominal distension for more than six months. Imaging examination revealed a large retroperitoneal mass. Finally, the patient was diagnosed with giant RPLS. The tumor occupied the entire abdominal cavity, severely compressed the abdominal organs, and adhered tightly to the bilateral ureters. After careful preoperative preparation (including three-dimensional visualization and bilateral ureteral stent implantation), we performed resection of the large retroperitoneal mass. The tumor was completely removed and consisted of multiple masses, with a total weight of 17 kg and the largest mass size of 35 cm × 28 cm × 14 cm. Postoperative pathological results revealed that the mass was a well-differentiated liposarcoma. The patient recovered well after surgery, and there was no sign of recurrence after 2 months of follow-up.

CONCLUSION

Surgical resection is the only radical treatment for giant RPLS. Preoperative preparation is essential, and three-dimensional visualization reconstruction is helpful for the formulation of surgical plans. Postoperative radiotherapy and neoadjuvant therapy can be reasonably selected, but whether they can reduce the recurrence rate is still controversial.

Key Words: Retroperitoneal tumor; Giant; Liposarcoma; Treatment; Case report

Core Tip: Retroperitoneal liposarcoma (RPLS) is a rare malignant tumor. When its diameter exceeds 30 cm or its weight is no less than 20 kg, it is classified as giant RPLS, which significantly increases the complexity of surgical intervention. Giant RPLS may necessitate concomitant resection of adjacent organs and cannot be completely resected, leading to a high recurrence rate and suboptimal treatment outcomes.

INTRODUCTION

Retroperitoneal liposarcoma (RPLS) is a rare malignant tumor originating from adipose tissue and accounts for < 1% of all malignant tumors[1]. The age of onset is primarily between 55 years and 75 years, and there are slightly more males than females[2]. Due to its deep location and concealed onset, the clinical manifestations of RPLS are not obvious, and there are no typical symptoms or signs. A few patients only experience compression symptoms of abdominal organs, which are often massive tumors at diagnosis, especially those with a diameter of > 30 cm or a weight of ≥ 20 kg, called giant RPLS[3], which seriously increases the difficulty of surgery. It may be combined with other organ resection or may not be completely resected, the recurrence rate is high, and the treatment effect is not ideal. This article describes a case of a giant RPLS with a maximum diameter of 35 cm and a weight of 17 kg. The tumor adhered tightly to the bilateral ureteric region. After careful preoperative preparation, the tumor was completely removed without damage to the abdominal organs. This case will help clinicians fully understand giant RPLS and make corresponding treatment plans.

CASE PRESENTATION

Chief complaints

Abdominal distension for over six months.

History of present illness

The patient, a 62-year-old female, was admitted to Yichang Central Hospital with a chief complaint of "abdominal distension for over six months". Abdominal ultrasound revealed a large retroperitoneal mass suspected to be a lipoma (extending from the subxiphoid region to the pubic symphysis, right to the adrenal gland, and left to the splenic flexure of the colon). For further evaluation and treatment, she was admitted to Tongji Hospital, Affiliated with Tongji Medical College of Huazhong University of Science and Technology, on February 7, 2025, with a provisional diagnosis of retroperitoneal tumor. At admission, she reported no obvious abdominal pain or other discomfort. Since the onset of symptoms, the patient's mental status, appetite and sleep have remained normal, with regular bowel and urinary habits and an increase in both physical strength and weight.

History of past illness

Her medical history included hypertension for 5 years that was adequately managed with oral nifedipine sustained-release tablets.

Personal and family history

The patient's family history had no notable findings.

Physical examination

Physical examination revealed marked abdominal distension (abdominal circumference: 95 cm), with a palpable, massive, soft and ill-defined abdominal mass, without tenderness or rebound pain.

Laboratory examinations

Laboratory examinations show no significant abnormalities.

Imaging examinations

Contrast-enhanced abdominal computed tomography (CT) further revealed a giant retroperitoneal mass, suggestive of a neoplastic lesion, likely liposarcoma. Additional findings included a nodule in the right hepatic lobe (suspected hemangioma), a small cyst in the left hepatic lobe, and minimal ascites in the abdominal and pelvic cavities. At the same time, three-dimensional visualization reconstruction was performed (Figure 1).

Figure 1 Three-dimensional visualization reconstruction. A: Three-dimensional reconstructed image; B: Cross section of the abdominal computed tomography (CT); C: Coronal view of the abdominal CT; D: Sagittal view of the abdominal CT.

FINAL DIAGNOSIS

Giant RPLS (high differentiation).

TREATMENT

Ultrasound-guided tumor biopsy was performed, and histopathological analysis revealed a mesenchymal tissue-derived tumor. Subsequent immunohistochemical and molecular detection confirmed the diagnosis of liposarcoma (considering high differentiation). To prevent intraoperative ureteral injury, bilateral ureteral stents were preoperatively placed via cystoscopy under general anesthesia. The surgery was performed on February 19, 2025, and involved resection of the giant retroperitoneal mass.

OUTCOME AND FOLLOW-UP

The tumor was completely removed and consisted of multiple masses, with a total weight of 17 kg and the largest mass size of 35 cm × 28 cm × 14 cm (Figure 2). Postoperative pathological examination and molecular results of the puncture specimen (II25-08446) confirmed a well-differentiated liposarcoma (WDLS)/atypical lipomatous tumor. Immunohistochemical analysis revealed the following marker profile: (1) Mouse double minute 2 (MDM2) (+); (2) Cyclin-dependent kinase 4 (CDK4) (+); (3) P16 (+); (4) S-100 (+); and (5) Ki-67 (labeling index of approximately 10%). Molecular detection revealed MDM2 gene expansion (Figure 3). The patient recovered uneventfully and was discharged on postoperative day 15. Later, radiation therapy was performed in the oncology department. At a follow-up of 2 months, a reexamination of contrast-enhanced CT of the whole abdomen revealed no evidence of recurrence (Figure 4).

Figure 2  Postoperative tissue specimen (maximum 35 cm × 28 cm × 14 cm).

Figure 3 Molecular detection revealed mouse double minute 2 gene expansion. A and B: Tissue staining (hematoxylin and eosin 10 × 20); C and D: Immunohistochemistry; E and F: Molecular detection.

Figure 4  Contrast-enhanced abdominal computed tomography after 2 months.

DISCUSSION

RPLS is insidious and usually asymptomatic in the early stage. Due to the loose anatomical structure of the retroperitoneal space and the absence of rigid bony boundaries, retroperitoneal tumors often grow rapidly. As the mass grows, patients may develop abdominal distension and pain, and these symptoms are particularly exacerbated postprandially and accompanied by mild dyspepsia[4]. Patient evaluation is frequently delayed until palpable abdominal masses or local compressive symptoms manifest. By the time of hospital consultation, these tumors commonly exceed 20 cm in diameter, with an average weight of 15–20 kg[5]. Sun et al[6] conducted a comprehensive review of all the literature in the PubMed database and identified only 34 reported cases of giant RPLS (RPLS exceeding 30 cm in diameter). Among these 35 patients, 23 patients were male (65.7%), and 12 were female (34.3%). Giant RPLS is extremely rare. At present, there is a lack of clinical experience in its diagnosis, treatment, prognosis and follow-up, which poses a great challenge to doctors. Based on the literature, the difficulties in the diagnosis and treatment, surgical decision-making and long-term prognosis of giant RPLS are discussed below.

Diagnostic challenges and radiological differentiation

The preoperative diagnosis of giant RPLS relies heavily on imaging evaluation; however, distinguishing it from benign lipomas remains challenging. Previous reports indicate that well-differentiated RPLS typically presents on CT or magnetic resonance imaging (MRI) as predominantly lipomatous lesions. However, the presence of lipomatous lesions accompanied by septations or nodular enhancement should raise suspicion for malignancy[7-9]. However, the accuracy of imaging modalities in predicting histological subtypes is limited. In the present case, preoperative imaging revealed that the patient was initially misdiagnosed with "retroperitoneal lipoma", similar to the misdiagnosis reported by Nureta et al[10]. These findings emphasize the need to maintain a high degree of clinical suspicion for malignancy when evaluating masses containing minimal nonadipose components; moreover, preoperative needle biopsy should be considered when ambiguity persists. In this case, an ultrasound-guided needle biopsy was performed preoperatively, revealing a mesenchymal neoplasm. Subsequent immunohistochemical and molecular analyses confirmed the diagnosis of WDLS, thereby validating the malignant nature of the lesion.

Surgical timing and preoperative preparation

Surgery remains the primary treatment for giant RPLS. A comprehensive evaluation of the tumor size, growth rate and clinical symptoms is needed to determine the optimal timing of surgery. Studies have recommended early surgery for patients with tumors > 5 cm in diameter or those presenting with compression symptoms, whereas immediate resection is advised for giant RPLS (diameter > 30 cm) upon diagnosis[11]. Achour et al[12] reported a case of giant RPLS measuring 38 cm in diameter, which encased the left kidney and compressed the left ureter, resulting in hydronephrosis. Due to the extensive involvement of the tumor in the present case, the surgical team initially deemed it unresectable and opted for biopsy-confirmed neoadjuvant chemotherapy (gemcitabine) to reduce the tumor volume. However, after 1 year of treatment with no clinical improvement or tumor enlargement to 45 cm, multidisciplinary consultation led to attempted surgical excision, resulting in an R1 resection margin followed by adjuvant chemotherapy. These findings underscore the critical importance of timely surgical intervention in giant RPLS.

Preoperative preparation necessitates comprehensive imaging evaluation (CT/MRI) to delineate tumor-to-surrounding structural relationships, supplemented by multidisciplinary team consultation if necessary[13]. For hypervascular tumors, preoperative arterial embolization serves to mitigate the risk of intraoperative hemorrhage[5]. Given the substantial tumor burden of giant RPLS and the inherent complexity of the retroperitoneal anatomy, iatrogenic injury to adjacent structures—including the descending colon, pancreas, kidneys, and ureters—is a critical concern. Surgical challenges increase significantly when tumors infiltrate neighboring organs, tissues, or musculature. To address these risks, three-dimensional visualization reconstruction may be employed preoperatively. Compared with conventional CT and MRI, this advanced modality has enhanced spatial resolution, enabling comprehensive anatomical mapping of tumor interfaces with vital vascular and visceral structures. Such detailed imaging facilitates optimized surgical approach selection and precise margin determination[14]. Furthermore, prophylactic cystoscopic placement of bilateral ureteral stents preoperatively enables intraoperative ureteral identification, substantially reducing inadvertent ureteral injury during dissection.

Surgical decision-making and the necessity of multivisceral resection

Complete surgical resection (R0/R1) constitutes the cornerstone for giant RPLS management, improving the 5-year survival rates from 16.7% to 58%[6]. For giant RPLS, resection of the involved organs is frequently required to achieve R0 margins. Santangelo et al[15] systematically reviewed 157 RPLS resection cases and reported that approximately 65% necessitated the resection of adjacent organs (such as the kidneys, colon or musculature), which significantly increased the recurrence rates observed in patients who underwent tumor debulking alone compared with multivisceral resection cohorts. However, the literature also indicates that multivisceral resection may increase the risk of postoperative complications, so there is a particular need to carefully evaluate organ preservation in younger patients to balance functional outcomes[16]. Notably, some scholars advocate for organ preservation in the absence of definitive histopathological invasion. For example, Rachman and Hardja[3] reported a case of a 30-cm RPLS managed via tumor resection alone, achieving 3-month recurrence-free survival, suggesting that meticulous fascial plane dissection without radical resection may suffice for well-differentiated subtypes. Nevertheless, the pseudocapsule structure of RPLS often adheres to adjacent tissues, rendering intraoperative determination of "safe margins" heavily reliant on the experience of the surgeon. Wei et al[17] reported that a series of giant RPLS resulted in severe compression and deviation of the left ureter. During the operation, the iliac vessels, mesenteric vessels and other large vessels and tumor tissues were finely separated, and the ureter was protected to achieve complete resection of the tumor. The peripheral blood vessels and ureter were protected. Consequently, preoperative planning should be integrated with three-dimensional image reconstruction and intraoperative frozen pathology to dynamically adjust the resection boundaries.

Controversies regarding tumor size, histological subtyping and recurrence risk

The debate persists regarding whether tumor size is an independent risk factor for recurrence. Marjiyeh-Awwad et al[11], in a comprehensive review, emphasized that while large, well-differentiated RPLS has a high recurrence risk, histological subtype and margin status (R0 vs R1) remain the paramount prognostic determinants. The World Health Organization classifies liposarcoma into five principal subtypes: (1) WDLS; (2) Dedifferentiated liposarcoma (DDLS); (3) Myxoid liposarcoma; (4) Pleomorphic liposarcoma (PLS); and (5) Myxoid PLS[18]. The histological subtype serves as the primary prognostic indicator for local recurrence and distant metastasis. While well-differentiated variants demonstrate favorable prognoses, the presence of dedifferentiated components markedly increases malignant potential. The literature has shown that WDLS accounts for 40%-50% of RPLS cases and is characterized by strong local proliferative capacity but low metastatic rates, whereas DDLS and PLS are associated with significantly greater risks of recurrence and metastasis[19]. In the present case, postoperative pathology confirmed WDLS with focal dedifferentiation, a feature that aligns with the clinicopathological profile reported by Mansour et al[5]. This underscores the inherent heterogeneity of such tumors and the need for extensive tissue sampling to avoid underdiagnosis of aggressive components. A recent systematic analysis revealed that recurrence is not significantly correlated with tumor volume but is strongly associated with the presence of dedifferentiated components and margin status[15].

Evidence and controversies related to adjuvant therapy

The efficacy of postoperative radiotherapy or chemotherapy in reducing the recurrence rate remains unclear. It is generally believed that WDLS is less sensitive to radiotherapy and chemotherapy than are DDLS or high-grade sarcomas, which may respond to these treatments[20-22]. Kanthala et al[19] reported cases managed with surgery alone, whereas Herrera-Almario et al[22] administered adjuvant doxorubicin-based chemotherapy for recurrent cases with minimal therapeutic benefit. Adjuvant radiotherapy is currently recommended for high-grade tumors or positive surgical margins (R1) according to National Comprehensive Cancer Network guidelines; however, the clinical utility of this approach is constrained by toxicity profiles (such as radiation enteritis) in retroperitoneal malignancies[6]. Given that RPLS recurrence predominantly occurs locally, chemotherapy or targeted therapies (such as CDK4/6 inhibitors) may be considered for unresectable recurrent or metastatic lesions. Carboni et al[23] reported that chemotherapy for liposarcoma is a palliative treatment for advanced or metastatic disease, offering symptomatic relief and modest quality-of-life improvements. However, the overall therapeutic value of chemotherapy is still controversial in clinical practice[24,25], so further prospective studies are needed to clarify the indications and optimize treatment regimens.

Optimization of postoperative surveillance strategies

In light of the high local recurrence risk of RPLS (40%-80%)[15], contrast-enhanced abdominal CT or MRI is recommended every 3-6 months postoperatively for at least 5 years according to published guidelines[26]. Emerging evidence suggests that MRI combined with diffusion-weighted imaging may enhance the early detection of recurrent lesions, although large-scale validation is pending[11]. In addition, routine patient education is critical. In this case, self-monitoring protocols (e.g., recurrent abdominal distention, pain, or unintentional weight loss) were emphasized to expedite the diagnosis of recurrence.

CONCLUSION

Giant RPLS is a rare malignancy with insidious onset that is often diagnosed at an advanced stage. Surgical resection is the only radical treatment, and CT and MRI serve as cornerstone diagnostic tools. Three-dimensional visualization/reconstruction aids in preoperative planning. Reoperation can still be performed to treat local recurrence. For metastatic or unresectable tumors, radiotherapy and neoadjuvant therapies may be reasonably selected. In addition, multidisciplinary collaboration is critical, particularly in cases involving adjacent organ infiltration. Long-term postoperative surveillance is imperative because of the disease’s propensity for recurrence.