Benign Lipoid Neoplasm or Malignant Liposarcoma in Disguise? Diagnostic Dilemmas Pertaining to Lipomatous Neoplasms of the Retroperitoneum

Retroperitoneal benign lipoid lesions are extremely rare, representing about 2.9% of all primary retroperitoneal tumors. Despite being of benign origin, they can have severe complications. We report a case of an elderly Chinese male presenting with urinary obstruction and lower limb deep vein thrombosis, with computer tomography findings of an extending pre-sacral retroperitoneal lesion. Histology and fluorescence in situ hybridization investigations confirmed that the lesion was of benign lipoid origin. Patient was offered surgical intervention which he declined in view of age.