Distinct levels of DDIT3 Amplification in Dedifferentiated Liposarcoma Developing After DDIT3 Rearrangement in Myxoid Liposarcoma.

Dedifferentiated liposarcoma (DDLPS) is a high-grade tumor characterized by its diverse histomorphology and development from atypical lipomatous tumor/well-differentiated liposarcoma (ALT/WDLPS). The variable morphology of DDLPS, particularly its similarity to myxoid LPS, necessitates a reliable diagnostic tool for accurate diagnosis. While DDIT3 rearrangement is a known characteristic of myxoid LPS, its amplification in DDLPS has not been extensively studied. To investigate this, we evaluated DDIT3 amplification in 29 DDLPS cases from Asan Medical Center over a 7-year period using fluorescence in situ hybridization, with immunohistochemistry for MDM2 and CDK4 performed for diagnostic confirmation. Our findings revealed DDIT3 amplification in 89.7% (26/29) of DDLPS cases, with a mean copy number of 7.4. While no significant differences in clinical characteristics or outcomes were observed between patients with and without DDIT3 amplification, patients with <4 copies of DDIT3 amplification showed a tendency toward shorter disease-free survival. These findings demonstrate the prevalence of DDIT3 amplification in DDLPS, suggesting its potential diagnostic and therapeutic significance. Additional research is necessary to fully understand the prognostic implications of DDIT3 amplification levels in DDLPS and its potential application in targeted therapies.