Oil Red O stain might be used to demonstrate which tumor type?

• A. Chondrosarcomas
• B. Liposarcomas
• C. Osteosarcomas
• D. Fibrosarcomas

Answer: (B)

Oil Red O stains neutral lipids such as triglycerides and cholesterol esters. Because lipids are dissolved during routine paraffin processing, this stain is used on frozen sections to visualize intracellular lipid droplets. Liposarcoma is a tumor of fat-forming cells and contains lipoblasts with abundant cytoplasmic lipid vacuoles, which Oil Red O highlights as bright red droplets. Other sarcomas like chondrosarcoma, osteosarcoma, or fibrosarcoma have little to no intracellular neutral lipid content, so they don’t show the same lipid-positive staining pattern. Therefore, Oil Red O is best used to demonstrate lipogenic tumors, such as liposarcoma.