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Well-Differentiated Liposarcoma of the Psoas Muscle: A Distinct Anatomic Subset with Highly Favorable Outcomes
William W Tseng1, Francesco Barretta2, Marco Fiore3
1Division of Surgical Oncology, Department of Surgery, City of Hope National Medical Center, Duarte, CA, USA. wtseng@coh.org.
Annals of Surgical Oncology
|May 5, 2026
Summary
Well-differentiated retroperitoneal liposarcoma in the psoas muscle shows excellent outcomes after surgery, with no local recurrences or disease-specific deaths. This suggests a potentially more conservative management approach for this specific liposarcoma subtype.
Area of Science:
- Surgical Oncology
- Sarcoma Research
- Medical Imaging
Background:
- Retroperitoneal liposarcoma (LPS) classification relies on histologic subtype and grade.
- A specific subset, well-differentiated (WD) LPS located in the psoas muscle, requires further outcome definition.
Purpose of the Study:
- To define the clinical outcomes for patients with well-differentiated retroperitoneal liposarcoma located in the psoas muscle.
- To compare these outcomes with those of non-psoas retroperitoneal and extremity liposarcomas.
Main Methods:
- Retrospective review of patients with primary WD LPS undergoing complete resection (March 2006-September 2021).
- Stratification into three groups: psoas WD LPS, non-psoas RP LPS, and extremity LPS.
- Estimation of crude cumulative incidences for local recurrence (LR) and disease-specific death (DSD).
Main Results:
- No local recurrences (LR) were observed in the 12 psoas WD LPS patients (Group A) over a median follow-up of 8.8 years.
- Psoas tumors were large (median 20.0 cm), with some requiring muscle/nerve resection (33%).
- Five-year LR incidence was 16.3% for non-psoas RP LPS (Group B) and 2.9% for extremity LPS (Group C); 5-year DSD was 1.9% for Group B and 0% for Groups A and C.
Conclusions:
- Psoas WD LPS demonstrates highly favorable local control and survival rates post-surgery, comparable to extremity liposarcomas.
- A more conservative management strategy may be suitable for this anatomically defined subset of RP LPS, pending multicenter validation.
