prior ALT/WDL; or who present with a retroperitoneal liposarcoma (DDL constitutes ~57% of all retroperitoneal liposarcomas). DDL tumors only rarely (<1% of cases) present as superficial skin tumors; are almost 5 times less likely than ALT/WDL to occur in the eye socket; and are extremely rare in children. Detection of tumor cell MDM2 amplification is the diagnostic gold standard in distinguishing WDL from lipomas, dysplastic lipomas, atypical spindle cell sarcomas, pleomorphic lipomas, and solitary fibrous tumors. Alternately, detection in the tumor cells of an overexpressed CDK4 gene or the presence of either the specific ALT/WDL-associated sSMCs or giant marker chromosome strongly support the diagnosis of DDL or ALT/WDL. The clinical presentation, histopathology, and gene differences (e.g. tumor cell overexpression of the cJUN gene strongly favors the diagnosis of DDL over ATL/WDL) between the latter two liposarcoma forms usually help distinguish between them. Treatment and Prognosis Complete surgical resection is usually the recommended first-line treatment for localized DDL tumors. However, emerging studies suggest that patients with DDL tumors that are restricted to an extremity or the trunk and have a predicted 10-year tumor-related overall survival of 51% or less have improved outcomes when chemotherapy (e.g. doxorubicin plus ifosfamide) is added to their surgical regimens. For these localized forms of DDL, perioperative radiotherapy following National Comprehensive Cancer Network guidelines may also be considered. Retroperitoneal DDL is the most common, surgically unassessible and serious form of DDL: it has a recurrence rate of 66% and a five-year overall survival rate of 54%. The primary treatment option for retroperitoneal DDL is surgical resection. A phase III clinical trial found little difference in the results of radiation therapy followed by surgical resection compared to surgical resection alone in the treatment of retroperitoneal DDL. In other phase III clinical trials, DDL patients with inaccessible retroperitoneal and/or metastatic tumors were treated with front-line chemotherapy comparing doxorubicin to doxorubicin plus ifosfamide or doxorubicin to gemcitabine plus docetaxel. Other studies have likewise examined the value of various chemotherapy regimens. These studies often found little difference in the overall survival times in their comparisons but did show some improvements in progression-free survival and other clinical parameters. Based on these studies, a recommended first-line therapy for retroperitoneal and other surgically inassessible or metastatic DDL tumors is treatment with an anthracycline-based chemotherapy regimen or, in tumor-resistant or relapsed cases, eribulin chemotherapy. A review conducted in 2020 reported median survival times for low