Clinicopathological characteristics and experience in the treatment of giant retroperitoneal liposarcoma: A case report and review of the literature

ABSTRACT

Retroperitoneal liposarcoma (RPLS) is a rare tumor, especailly those over 20 kg that are called “giant liposarcoma," whose characteristics and treatments remain relatively unknown. Herein, we report a giant RPLS measuring 65 × 45 × 30 cm in diameter and 31 kg in weight, which we successfully performed complete excision through interdisciplinary cooperation. The patient had an uneventful postoperative course and was discharged without complications. Afterwards he underwent radiotherapy and had no evidence of tumor recurrence or symptoms of metastasis at 3-month CT scan and 8-month follow-up. We also first review the 13 cases reported in literature published in PubMed regarding giant RPLS. Giant RPLS commonly occurs in adults aged 40–60 y and presents atypical clinical manifestations. CT scan is the most useful examination and preoperative biopsy is controversial. Complete surgical resection still remains the principal treatment. Giant RPLS can also be removed, even reach to R0 excision, by a multidisciplinary team in a specialized center after meticulous planning even though its gigantic tumor size. Local radiotherapy following surgery may improve the rate of recurrence. Besides, closely follow-up and routine examinations are required.

KEYWORDS:

• complete resection
• giant liposarcoma
• multidisciplinary cooperation
• retroperitoneal liposarcoma

Introduction

Liposarcoma, which appears to originate from primitive mesenchymal cells rather than from mature adipose tissue, is one of the most common soft tissue sarcomas, accounting 10–12% of all soft tissue sarcomas.^1-3 Furthermore, liposarcoma originating within the retroperitoneum is the most popular histologic type, which constitutes 41% of these tumors.² Retroperitoneal liposarcoma (RPLS) commonly occurs in adults aged 40–60 years, with a slight male predominance.³

Most tumors that grow to excessively large are benign (for example, ovarian mucinous cystadenomas).⁴ Unfortunately, RPLS is exceptional. These tumors are usually late to be detected owing to their absence of symptoms in retroperitoneum and reach a large size (> 15 cm) by time of diagnosis. However, resected tumors weighing over 20 kg are extremely rare and considered to be “giant liposarcoma.”⁵ Due to the rarity of giant RPLS, few surgeons know its clinicopathological features and gain enough experience in the treatment, thus resulting in delayed diagnosis and inadequated therapy. Herein, we report our experience in the treatment of a giant RPLS weighing 31 kg that we managed marginal resection. Meanwhile, we also provide a review of 13 cases of giant RPLS through PubMed search of English language articles. To the best of our knowledge, this review is the first document regarding its clinicopathological characteristics of giant RPLS and communicating the experience in treatment.

Case report

A 45-year-old male reported gradual increase in abdominal girth, without significant abdominal pain, nausea, vomiting, constipation or dyspepsia. On examination, a diffuse hard, non-mobile mass with ill-defined margins that occupied the entire abdomen was palpated and there was edema in both lower extremities (Fig. 1A), with a ECOG score of 2 and ASA score of 4. As for routine investigations, haemograms showed mild anemia (hemoglobin 80 g/L), renal and liver functions test were within normal limits. Computed tomography (CT) showed a bulky mass, with mixed content, mainly of fat density, filling the entire abdominal cavity (Fig. 2A and B). The scan also revealed the lump originating from the retroperitoneum probably indicative of RPLS. The intestinal loops and other abdominal organs were pushed aside but without signs of infiltration or distant metastasis.

Figure 1. A: Appearance of the retroperitoneal liposarcoma as a giant mass. B: At surgery, well-encapsulated tumor and its exact supplying vessels were found. C: Gross appearance of resected tumor, measuring 65 × 45 × 30 cm and weighting 31 kg. D: The cut section of the specimen, showing a homogenous, yellow look.

Figure 2. A and B: Abdominal computed tomography (CT) shows a heterogeneous retroperitoneal mass occupying the entire abdominal cavity, with stomach being pushed aside (red arrow). C and D: The 3-month follow-up CT scan, with the normal stomach (red arrow).

For the curative resection intention, we arranged CT aortography of abdominal aortic for him and performed bilateral intraureteral catheterization. Following this, an interdisciplinary team worked out a meticulous plan and then successfully performed en bloc resection of the tumor through a midline incision. In the operation, we found that the tumor originated from the omentum majus in front of caput pancreatis and was supplied by a branch of arteriae gastroduodenalis (Fig. 1B). The operation took 4 hours, and the estimated blood loss was only 400 mL. The specimen measured 65 × 45 × 30 cm and weighted 31 kg (Fig. 1C). Grossly, the tumor was well encapsulated and was consistent with R0 resection. The cut section showed a homogenous, yellow appearance (Fig. 1D). Histologic studies revealed a well-differentiated liposarcoma (Fig. 3A and B). According to the grading system of the French Federation of Cancer Centers (FNCLCC), the tumor was classified as grade I.

Figure 3. Histopathologic findings. A (original magnification, × 40; hematoxylin and eosin staining) and B (original magnification, × 100; hematoxylin and eosin staining) views demonstrate a well-differentiated liposarcoma.

In the beginning postoperative period, the patient required respiratory support. Spontaneous respiration reached a sufficient level 2 d later. Afterwards he had an uneventful postoperative course and was discharged without complications 10 d after the operation, and thereafter he underwent radiotherapy 3 weeks after surgery. In addition, the patient underwent follow-up CT scans at 3 months after surgery, there has been no evidence of tumor recurrence (Fig. 2C and D). To date, at 8-month follow-up, he had neither symptoms nor signs of recurrence or metastasis.

Review

In English literature, from 1975 to Octobor 2016, only 13 cases of giant RPLS have been reported (Table 1).^6-18 Of the 14 patients (including ours), there were 9 male (64.3%) and 5 female (35.7%) with a median age of 53 (39–72) years and they all presented atypical clinical manifestations such as abdominal distention or increasing in abdominal girth. All the 14 giant RPLS were diagnosed by CT scan. Besides, 4 cases (28.6%) took preoperative biopsy examination and made exact preoperative diagnosis of liposarcoma. In terms of histologic subtypes, 7 cases (50%) were well-differentiated, 4 cases (28.6%) were dedifferentiated and the rest of 3 cases (28%) were myxoid/round cell. All the 14 cases of giant RPLS underwent surgical operations and 12 of them (85.7%) achieved R0 excision, with half of combined resections, including 5 cases of nephrectomy and 2 cases of bowel resection. Surprisingly, the tumor weight of 6 cases (42.9%), which was nearly half of all, exceeded 40 kg, with the heaviest of 47 kg. Nevertheless, 3 cases (21.4%) had postoperative complications and recovered smoothly without a secondary operation. The follow-up ranged from 6–63 (median, 24) months, and 4 cases recurred at 9, 12, 16 and 40 months respectively.

Table 1. Clinical features, preoperative evaluation, type of therapeutic approach, histopathologic characteristics at diagnosis, follow-up and clinical outcomes of 14 patients with giant RPLS.

No.	Author/year	Sex/age (yr)	Main clinical presentation	Pre- imaging	Pre- histology	Type of intervention	Compli- cations	Weight (kg)	Size(cm)^a	Histological subtype	FNCLCC grade	Complete resection (R)	Adjuvant therapy	Follow- up(mo)	Evolution
1	Hazen B[6] 2016	M/64	Abdominal distention	CT	No	Wide excision	No	41	60×42×31	Poorly- differentiated	Grade III	Yes(R0)	No	NA	NA
2	Oh SD[7] 2016	F/71	Abdominal distention	US CT	No	Wide excision	No	25	45×30×11	Well- differentiated	Grade I	Yes(R0)	No	28	Local recurrence at 16 mo from diagnosis→resection
3	Sharma M[8] 2013	F/60	Increasing in weight and abdominal girth	CT	Yes (FNAC)	Wide excision	No	23	47×40×25	Well- differentiated	Grade I	Yes(R0)	No	6	No recurrence
4	Bansal VK[9] 2012	M/52	Abdominal distention, early satiety and dyspnoea	CT	No	Wide excision with 50 cm of ileum and right middle ureter along with autotransplantation of right kidney	No	24	40×35×35	Mixed	NA	Yes(R0)	No	63	Local recurrence at 40 mo from diagnosis→ resection and adjuvant chemo-radiotherapy
5	Amir M[10] 2011	F/72	Increasing in abdominal girth and prolonged ileus	CT	No	Subtotal piecemeal excision	No	46	NA	Poorly- differentiated	Grade II	No(R2)	No	6	Dead
6	Akhoondinasab MR[11] 2011	M/54	Enlargement of abdomen	US CT	No	Wide excision	Atelectasis	32	58×45×36	Well- differentiated	Grade I	Yes(R0)	No	36	Local recurrence at 12 mo from diagnosis→resection
7	De Nardi P[12] 2011	M/40	Increasing in abdominal girth	CT	No	Wide excision	No	42	50×49×35	Well- differentiated	Grade I	Yes(R0)	No	12	No recurrence
8	Hashimoto Y[13] 2010	M/41	Abdominal swelling, edema and respiratory failure	CT	Yes (FNCB)	Wide excision with right kidney	No	22	45×40×30	Poorly- differentiated	Grade II	Yes(R0)	No	12	No recurrence
9	Clar H[14] 2009	M/66	Increasing in abdominal girth, dyspepsia, asthenia and dyspnoea	CT	Yes (FNCB)	Wide excision with left kidney	Chylo- abdomen	25	47×42×25	Well- differentiated	Grade I	Yes(R0)	No	36	No recurrence
10	Benseler V[15] 2009	M/39	Abdominal distention, dyspnoea, nausea and vomiting	CT	No	Wide excision with left kidney and descending colon	No	45	60×50×36	Well- differentiated	Grade I	Yes(R0)	No	48	Local recurrence at 9 mo from diagnosis→resection
11	Morandeira A[16] 2008	F/63	Abdominal distention, edema and cachexia	CT	No	Wide excision with right kidney, appendix,cholecyst and hystera	No	31	45×43×24	Myxoid	Grade II	Yes(R0)	Chemo- therapy (doxo- rubicin)	24	No recurrence
12	McCallum OJ[17] 2006	F/47	Increasing in abdominal girth and anemia	CT	No	Local excision with hystera,bilateral tuboovarianabscess and paraaortic lymph node	ileus	47	50×48×45	Poorly- differentiated	Grade II	No(R1)	No	35	No recurrence
13	Yol S[18] 1998	M/63	Abdominal mass, constipation,dyspnea and severe edema	US CT	Yes (FNAC)	Wide excision with descending colon	No	42	50×45×32	Myxoid	Grade II	Yes(R0)	Radio- therapy	NA	NA
14	our case, 2016	M/45	Increasing in abdominal girth	CT	No	Wide excision	No	31	65×45×30	Well- differentiated	Grade I	Yes(R0)	No	8	No recurrence

Pre-: preoperative; US: ultrasonography; CT: computed tomography; FNAB: fine-needle aspiration biopsy; FNAC: fine-needle aspiration cytology; FNCLCC: French Federation of Cancer Centers grading system; NA: not available. ^aLongitudinal, transverse, and anteroposterior diameters.

Discussion

Retroperitoneal liposarcoma (RPLS) is a rare tumor accounting for less than 0.2% of all malignancies, but it is the most common variant of retroperitoneal tumor.² Giant RPLS that exceed 20 kg are extremely rare even though RPLS sometimes weigh as much as 10 kg or more. Similar to RPLS, giant RPLS occurs with a peak incidence between 40 and 60 y and affect male more frequently. Besides, giant RPLS are usually asymptomatic. Their most typical manifestations are discomfort or a palpable abdominal mass rather than emergences such as hematochezia, haematemesis or obstruction, resulting in their prolonged natural history and bulk.¹⁹ Given this, few surgeons gain enough experience in this field, with the diagnosis often being made late, and therapy is inadequate.

For giant RPLS, the most appropriate diagnostic tests is abdominal CT, which not only defines their size, consistency, and relation between the tumor and the adjacent tissue but also allows us to detect residual tumor and recurrences.²⁰ Meanwhile, selective angiography can help us realize the tumor blood supply so that we can work out a more detailed security plan. In our case, due to the preoperative CT aortography of abdominal aortic, we could ligate the supplying vessels of tumor exactly thereby only 400 mL blood loss in operation. Moreover, intravenous pyelography is necessary because unilateral nephrectomy is often required in complete resection.²¹ In great majority of RPLS, the CT imaging appearance (location, density, displacement, invasion and metastasis) is nearly diagnostic and preoperative biopsy seems unnecessary.²² Otherwise, image-guided percutaneous coaxial core needle biopsy is strongly suggested for those imaging are not pathognomonic.^23,24

RPLS can be classified into 4 histologic types (well-differentiated, myxoid/round cell, pleomorphic, and dedifferentiated) and 3 grades (grade I, II and III) according to the grading system of French Federation Cancer Centers (FNCLCC).²⁵ Among the 4 subtypes, well-differentiated (46%) were the most common form, followed by myxoid/round cell (28%), dedifferentiated (18%) and pleomorphic (8%), as Dalal²⁶ showed. Both the histologic subtype and grade were prognostic variables. In a large cohort of 72 patients with primary RPLS, Neuhaus²⁷ found that R0 excision and histologic grade I were the only variables significantly associated with a decrease in the rate of local recurrence. In a recent study, Gronchi²⁸ reported that overall 5-year survival for well-differentiated subtypes was 90%, contrasting to 30–50% of pleomorphic subtypes. The rate of de-differentiated and myxoid/round cell subtypes was 75% and 60–90%, respectively.

Complete surgical resection is the cornerstone of therapy, and it is the most consistent prognostic factor.²⁹ Size alone does not contraindicate complete resection of giant RPLS, which is currently the only potentially curative treatment. Even huge, those bulks can be removed as well by a multidisciplinary team in a specialized center, which is consistent with the consensus management of RPS in the adult.³⁰ It has been demonstrated³¹ that they can be successfully resected obtaining negative microscopic margins with combined resection of involved organs such as kidney, ureter and large bowel. Long-term prognosis without complete resection is poor with average 5 and 10-year survival rates of 16.7% and 8.0% respectively.³² Lewis³³ reported their single-institutional data of 500 retroperitoneal sarcoma cases, a median survival of 103 months for those who underwent complete resection with grossly negative margins in contrast to 18 months for those who underwent incomplete resection.

Retroperitoneal location is itself a negative prognostic factor for the reason that the retroperitoneal provides a sizeable potential space allowing significant growth before appearance of clinical signs and symptoms. Meanwhile, local recurrence and distant metastasis closely related to the tumor size. The 5-year rate of metastasis is approximately 3% when the size of the tumor is less than 2.5 cm. Nevertheless, the rate is multiplied to 55–60% in case that tumors are larger than 20 cm.¹⁷ To obtain clear surgical margins and considering the highly aggressive nature of retroperitoneal liposarcomas and their propensity for local recurrence and distant metastasis, complementary adjuvant/neoadjuvant therapy may be required.³⁴ However, adjuvant therapy including chemotherapy and radiotherapy are of few study-proven value and just benefit a minority of patients.^35-37 Furthermore, after 2 small randomized trials, Beane³⁸ and Yang³⁹ et al. argued that postoperative radiotherapy improved local control only instead of overall survival.

Large tumor size should not be regarded as a contraindication to surgical resection. Even gigantic, complete surgical cure can also be achieved in giant RPLS with a thorough program. Giant RPLS patients are usually malnourished, hypoproteinemia or anemia as a result of tumor consumption. Therefore, much longer preoperative interval for enteral or parenteral nutrition support to improve patients’ condition is indispensable. Multidisciplinary cooperation is particularly important in the treatment of gaint RPLS. Furthermore, prudent surgical program and closely monitoring vital sign intra-operation play significant role in the whole course of the patients’ hospitalization period. Moreover, meticulous management of postoperation is crucial component of the entire process. Finally, long-term follow-up CT scan is also considered to be important, especially within 2 y after initial resection, which is peak recurrence period of giant RPLS.⁴⁰

Conclusions

In summary, giant RPLS is aggressive tumor and particularly rare, with no typical presentation. CT scan is the most valuable examination for diagnosis. It can be completely resected, oftentimes with combined resection of unilateral kidney and/or intestines, by an intradisciplinary team in a specialized center even though its huge tumor size. Of the whole process, multidisciplinary cooperation and meticulous preoperative preparation are particularly important. Postoperative radiotherapy may improve local control. R0 excision, histologic subtype of well-differentiated and grade I are the most significant prognostic risk factors. Long-term follow-up examination is absolutely necessary as well.

Disclosure of potential conflicts of interest

No potential conflicts of interest were disclosed.

Funding

This study was suppoted by National Natural Science Foundation of China (No. 81572413) and Scientific and Technological Application Foundation Project of Wuhan (No. 2015060101010044).