A rare case of abdominal (lesser sac) myxoid liposarcoma: A case report

Abstract

Background and importance

Myxoid liposarcomas (MLS) are genetically defined by DDIT3 gene fusions and most commonly arise in the extremities. They can also occur in the retroperitoneum as a primary site. However, there are controversies in its occurrence. It peaks in the fourth and fifth decades of life, affecting both gender equally.

Case presentation

A 38-year-old male patient presented with painless abdominal swelling, indigestion, and loss of appetite of 08 months duration. The abdominal examination showed a regular non-tender mass filling the left upper quadrant mimicking huge splenomegaly. An abdominopelvic ultrasound shows a huge echo complex mass filling the left upper abdomen. A contrast CT scan revealed a well-defined mass filling the lesser sac with a moderate mass effect on nearby abdominal organs with a clear fat plane and hence with no sign of invasion. Laboratory tests were found to be in the normal range except moderate anemia. Laparotomy was decided after case analysis and correction of anemia. A huge mass excised from the lesser sac and sent for histology. The patient went home on the third day after laparotomy. Histopathologic results reported retroperitoneal MLS with the classic microscopic findings.

Clinical discussion

MLS is the second most common type of liposarcoma, and tends to occur in the lower extremities. It rarely occurs in the retroperitoneum, with most cases being classified as atypical lipomatous tumors with prominent myxoid change.

Conclusion

It is crucial to differentiate a metastatic MLS originating from the lower extremities. The principle of treatment is complete surgical resection.

Highlights

• •The presence of DDIT3 gene fusions genetically defines myxoid liposarcomas.
• •Epidemiologically, it peaks in the fourth and fifth decades of life, equally affecting both genders.
• •It is the second most common type of liposarcoma, with a marked predilection of lower extremities.
• •It practically never occurs in the retroperitoneum.
• •The principle of treatment for liposarcoma is a complete surgical resection.

1. Introduction

Myxoid liposarcoma (MLS) is the second most common type of liposarcoma, with a strong preference for the lower extremities, especially the thigh and popliteal fossa. It rarely occurs in the retroperitoneum and the most diagnosed cases are atypical lipomatous tumors (ALT) with significant myxoid change [1,2]. Therefore, it is crucial to rule out metastatic myxoid liposarcoma from the lower extremities and assess for the presence of DDIT3 gene fusions [3].

The clinical presentation of retroperitoneum liposarcoma differs from liposarcomas from other locations. In addition to presenting as an abdominal mass, it may cause symptoms such as urinary and intestinal obstruction, due to the tumor's impacts to these structures [4].

Microscopically, MLS exhibits few or no mitotic figures and is characterized by proliferating lipoblasts in various stages of differentiation. It also features a prominent anastomosing (“chicken wire”) capillary network, and a mucoid matrix rich in hyaluronidase-sensitive acid mucopolysaccharides [[5], [6], [7]].

2. Case presentation

A 38-year-old male patient presented with a complaint of painless abdominal swelling, indigestion, and loss of appetite of 08 months duration. On physical examination, his vital signs were within normal ranges (BP = 124/81 mmHg, PR = 98 bpm, RR = 18 bpm, and SPO2 = 98 %). An abdominal examination finding was a regular non-tender mass filling the left upper quadrant mimicking huge splenomegaly. An abdominopelvic ultrasound shows a huge (15 × 15 cm) echo complex mass filling the left upper abdomen. The spleen and other intra-abdominal organs were reported normal. The liver was free and no enlarged mesenteric lymph node. A contrast enhanced abdominopelvic CT scan was conducted, showing a large left upper quadrant abdominal mass, well-defined heterogeneously a hypodense mass grossly measuring 17.9 × 14.9 × 13.8 cm with internal foci of calcification and fat; the mass has a moderate mass effect on the stomach, pancreas, spleen, and left kidney with no loss of fat plane. The conclusion of the CT scan indicated a likely teratoma (Fig. 1).

Fig. 1.

CT SCAN finding.

3. Surgical procedure

After obtaining written consent, a laparotomy was performed. The intra-operative finding was a huge hard well encapsulated mass in the lesser sac, with no attachment to adjacent organs. The mass was successfully excised and sent for histopathologic examination. The patient was discharged home on the third day after surgery (Fig. 2).

Fig. 2.

Intra-operative finding.

3.1. Pathologic findings

3.1.1. Gross/Macroscopic description

The mass in formalin was globular and nodular, with a smooth surface and firm tissue measuring 12 X 18 X 12 cm. The cut section shows well defined solid yellowish–white mass with areas of myxoid changes and necrosis (Fig. 3).

Fig. 3.

Gross examination shows well defined solid yellowish to white mass with areas of myxoid changes and necrosis.

3.1.2. Microscopic description

Microscopic section showed encapsulated tumoral tissue composed of a mainly hypocellular area containing bland round to stellate cells dispersed in myxoid stroma along with arborizing chicken wire-like blood vessels, pulmonary edema-like pattern and variably sized adipocytes mixed with signet rings like lipoblasts and metaplastic bone formation. The tumor was signed out by pathologists as retroperitoneal myxoid liposarcoma having histologic grade-II, stage pT4NxMx, mitosis-0/10 HPF, focal necrosis with a negative margin and 23 cm of maximum tumor size (Fig. 4).

Fig. 4.

Microscopic examination shows encapsulated tumor mainly composed of myxoid stroma along with areas of chicken wire blood vessels and metaplastic bone formation.

3.2. Post-operative outcome

The patient started sips on the postoperative of 48 h and a soft diet on the following day. He was discharged on the 5th postoperative day without any remarkable events. He was advised on danger signs and discharged with an appointment.

4. Discussion

The work has been reported in line with the SCARE criteria [8]. Retroperitoneal sarcomas are rare tumors that account for only 1 %–2 % of all solid tumors. Most sarcomas occur outside of the retroperitoneum with only 10 %–20 % originating in the retroperitoneal space. They are a group of heterogeneous neoplasms with wide histological varieties; the most frequent histological types are liposarcomas (49 %), leiomyosarcomas (29 %), and malignant fibrous histiocytomas. Liposarcoma is the most common soft tissue sarcoma, accounting for 20 % of all sarcomas in adults [[9], [10], [11]]. The extent of differentiation, reflected by histologic grade remains the most important determinant of clinical course and the ultimate prognosis of patients with liposarcoma after resection [[12], [13], [14]].

Liposarcoma is quite rare in adolescents and children, but unequivocal cases have been reported. It is usually large and occurs most frequently in the lower extremities, retroperitoneal, perirenal, mesenteric region, and shoulder area. In their classic article on liposarcoma, Enzinger and Winslow divided liposarcomas into four histologic types: myxoid, round cell, well-differentiated, and pleomorphic, acknowledging the existence of mixed forms [3].

MLS more commonly appear in the extremities of young adults. However, the retroperitoneum may be the primary site. In order to characterize its sources of location as primary the retroperitoneum, it is necessary to exclude that they are not metastatic lesions, as the extremity myxoid liposarcoma frequently metastasizes to the retroperitoneum [15].

Myxoid liposarcomas are genetically defined by the presence of DDIT3 gene fusions and most commonly arise in the extremities of young adults. Whether it develops primarily in the retroperitoneum is controversial and a recent retrospective study found no molecularly confirmed examples. Because it tends to metastasize to deep soft tissues, reported examples of primary retroperitoneal lesions might represent distant metastasis, most commonly from the extremities. Additionally, well-differentiated or dedifferentiated liposarcomas, characterized by MDM2 amplifications, may exhibit prominent myxoid changes and mimic MLSs [[16], [17], [18], [19], [20]].

5. Conclusion

The principle of treatment for liposarcoma is complete surgical resection. It is generally agreed that the most important factor influencing the survival outcome of RPLS is the surgeon's skill in resecting the tumor completely. In addition, tumor histology, negative margins after surgery, metastases, and tumor size are independently associated with disease-specific survival, patients with decreased local recurrence rate after adjuvant therapies, and patients with local recurrence having lower survival rates.

Microscopically it has few or no mitotic figures and is characterized by proliferating lipoblasts in different stages of differentiation, a prominent anastomosing (“chicken wire”) capillary network, and a mucoid matrix rich in hyaluronidase-sensitive acid mucopolysaccharides. The presence of a delicate network of thin-walled vessels is an important feature in the differential diagnosis of myxoma and other myxoid tumors. The mucoid extracellular material may accumulate in large pools (so-called “pulmonary edema” pattern), thus simulating a tumor of lymph vessel origin. Metaplastic cartilage is found in rare instances.

Author contribution

SA, BM, AK were actively engaged in the patient evaluation and management; MM, WT contributed in revision of the manuscript; WRD developed the manuscript.

Consent

Written informed consent was obtained from the patient for the publication of the case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.

Ethical approval

Ethical approval for this study was provided.

Guarantor

Seifu Alemu, Bilisuma Mulatu and Abdo Kedir will take the primary responsibility of the report.

Research registration number

• 1.Name of the registry: Research registry (RR): A rare case of abdominal (lesser sac) myxoid liposarcoma: A case report.
• 2.Unique identifying number or registration ID: researchregistry10925.
• 3.Hyperlink to your specific registration (must be publicly accessible and will be checked): https://www.researchregistry.com/browse-the-registry#home/.

Provenance and peer review

Not commissioned, externally peer-review.

Funding

This work does not receive any funds.

Conflict of interest statement

The authors declare that they have no competing interests.