The degree of sclerosis is associated with prognosis in well-differentiated liposarcoma of the retroperitoneum

Background and Objectives: Well-differentiated liposarcomas (WDL) are often partly composed of sclerotic tissue, however, the amount varies widely between tumors, and its prognostic significance is unknown. We hypothesized that tumors with more sclerosis would behave more aggressively. Methods: Primary retroperitoneal WDL from 29 patients resected at our institution with follow-up were histologically evaluated by soft tissue pathologists blinded to outcome. Tumors with ≥ 10% sclerosis were designated “sclerotic” while tumors with < 10% sclerosis were designated as “minimally sclerotic”. Cellular and dedifferentiated tumors were excluded. Clinical parameters and radiologic assessments on computed tomography (CT) were recorded. Results: Histological evaluation identified 13 minimally sclerotic WDL and 16 sclerotic WDL. Median follow-up was 9 years (range, 3-20). Median recurrence-free survival (RFS) and median overall survival (OS) were 6.16 and 13.9 years, respectively. Compared with patients with sclerotic WDL, those with minimally sclerotic WDL had superior RFS (HR = 0.17 [95% CI, 0.06-0.53], P =.002) and OS (log-rank test, P =.002). Sclerotic WDL exhibited higher Houndsfield Units than minimally sclerotic WDL (26 vs 1, P =.040). Conclusions: Minimally sclerotic WDL were associated with more favorable outcome compared with sclerotic tumors. Assessment of sclerosis in WDL is likely a useful prognostic marker.