Imaging for retroperitoneal liposarcoma includes a CT scan of the chest, abdomen, and pelvis, with metastasis present in up to 50% of these images2. Well differentiated tumors appear homogenous in nature and similar to surrounding adipose tissue with septations throughout the mass, while the undifferentiated subtype is heterogenous without similarities to surrounding fat7. MRI may also be a useful adjunct to identify satellite lesions and further demarcate boundaries of the tumor7. Surgical planning and intervention may be based on imaging findings alone. Biopsy for liposarcoma is unnecessary unless distal disease is present or it invades vital structures. In this case, biopsy is recommended to direct systemic therapy5.
The primary treatment of liposarcoma is complete macroscopic resection8. Up to 40 percent of patients require contiguous organ removal. The organ most commonly taken is the kidney, followed by the colon9. En bloc resection with negative margins confers the greatest opportunity for remission. If there is tumor invasion into important neurovascular structures, the overlying fascial layer of the structure is taken to optimize margins without taking the structure itself10. However, these patients have a high rate of recurrent disease. It has been cited that local recurrence occurs in 2/3 of patients with retroperitoneal liposarcoma secondary to difficulty in obtaining adequate margins2. Our patient had involvement of the margin of his resection and due to the location of his tumor will likely have a high risk of recurrence. This will make postoperative adjuvant therapy and surveillance an important aspect of his course.
Adjuvant therapy recommendations remain controversial as neither chemotherapy or radiation have shown significant survival benefit in well differentiated or dedifferentiated liposarcoma8. Adjuvant radiation should be considered in patients with high risk for recurrence, such as in our patient. Placing clips at the margins of resection is helpful for deciding precise locations to radiate, however in our patient, no clips were placed because his tumor involved the entire retroperitoneum. Neoadjuvant radiotherapy has been associated with increased wound complications, particularly in the extremities, as opposed to receiving radiation postoperatively. This is one reason a multidisciplinary approach is imperative in the liposarcoma patient10. There have been multiple case reports demonstrating the efficacy of neoadjuvant chemotherapy in treating dedifferentiated liposarcoma of the retroperitoneum11. Currently, there is no consensus of the role of chemotherapy overall in the treatment of liposarcoma. Further randomized control trials should be completed to evaluate its efficacy. This patient will be followed as an outpatient and presented at tumor board to determine his appropriate next steps in treatment.
Local recurrence is the most common cause of mortality in these patients. Because of this, patients require routine surveillance imaging by CT scan every three to six months for 3 years, then every six months for two years, and annually thereafter6. Pathologic grade of tumor is the most important prognostic factor and predictor of local recurrence8. Other factors influence the rate of local recurrence including gross residual disease, tumor rupture, high grade and positive margins12.
In conclusion, retroperitoneal liposarcoma is a rare form of cancer that requires a multidisciplinary approach to treatment. Our case is an example of a well differentiated retroperitoneal liposarcoma that was treated with primary resection.