Chordoma 

• A malignant tumor with notochordal differentiation
•  involves the clivus, sacrococcygeal bones or vertebrae
• T gene (brachyury) duplication (6q27)
• Cells with bubbly cytoplasm (physaliphorous cells) are diagnostic of chordoma -  You need not be efficient in identifying them on microscopy -  You will have a history to pick them up. 
• Physaliphorous =  Bubble. 
  
  

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