LAUSR

Preoperative diagnosis is a cornerstone of surgical oncology. Nonetheless, in the past, fine-needle aspiration and core needle biopsy in retroperitoneal sarcoma (RPS) were considered to rarely yield a correct diagnosis. In addition, they were considered at risk of complications, such as bleeding and tumor seeding. As a result, most RPS series before 2015 still reported preoperative biopsy in only 40–50% of patients. In recent years, improved diagnostics, molecular testing, and protected coaxial needle have become available, and percutaneous biopsy in RPS has been proven safe in terms of potential complications and seeding. Indication for percutaneous biopsy has therefore been strongly advocated by expert consensus as a standard approach in all suspected RPS. Moreover, robust data about different risk patterns in single histological subtypes have become available. Retroperitoneal liposarcoma (LPS) represents the main histology, and within this well-differentiated LPS (WDLPS), grade 2 and grade 3 dedifferentiated LPS (DDLPS) have different prognoses. PRESENT