Retroperitoneal liposarcomas are uncommon. They typically produce few symptoms until they become sufficiently large to be incidentally discovered or compress surrounding structures. Herein, we report a case of retroperitoneal liposarcomas that clinically presented as flu-like symptoms and review relevant literature to introduce the current treatment. Recognizing this rare form of presentation is crucial to diagnosing liposarcomas early and should be considered in the differential diagnosis of acute upper respiratory infection when a palpable abdominal mass is present.