Is the nonlipomatous component of dedifferentiated liposarcoma always soft tissue on CT? Analysis of CT densities and correlation with rate of growth in 60 patients

Abstract

Purpose

To define the various CT densities of nonlipomatous component of dedifferentiated liposarcoma (DDLPS) and to determine if the rate of growth varies with density.

Methods

This study identified 60 patients with DDPLS (38 men, 22 women; mean age at diagnosis 59 years, range, 35–82 years) who had one or more resections. CT scan immediately before the surgical resection (presurgery) and up to a maximum of one year before the surgery (baseline) was reviewed by two radiologists to note the density of the nonlipomatous elements and rate of growth during that period. Clinical and histopathological data were extracted from electronic medical records. Rate of growth of various densities was compared using Kruskal–Wallis test.

Results

Three distinct densities of the nonlipomatous component were noted: soft tissue density (SD), fluid density (FD), and mixed density (MD). Of 109 lesions on the presurgery scan (SD = 78; MD = 22; FD = 9), scans at baseline were available for 72/109 lesions (SD = 49; MD = 14; FD = 9). Median growth rate/month without treatment, with chemotherapy, and with radiotherapy were 40%, 24%, and 62%, respectively, for SD lesions and 28%, 61%, and 52% for MD lesions. For FD lesions, it was 72% and 35%, respectively, without treatment and with chemotherapy. There was no statistical difference in the rate of growth of various densities. Density changed over time in 8/72 (11%) lesions, including 2/49 SD lesions (to MD), 1/14 MD lesions (to SD), and 5/9 FD lesions (to SD).

Conclusions

DDLPS has three distinct CT densities of which soft tissue density is the most common. Despite not being statistically significant, fluid density lesions had rapid growth rate and often converted to soft tissue density in our study.