The inventon relates to antibodies that react with a variant epilope in the extracellular region of a variant CD44 polypeptide, wherein the variant epitope has the amino acid sequence:I S S T I S T T P R A P D H T K Q N Q D W T Q W N P S H S N P EV L L Q T T T R M T D V D R N G T T A Y E G N W N P E A H P P LI H H E H H E E E E T P H S T S T I O A T P S S T T E E T A T QK E Q W F G N R W H E G Y R Q T P R E D S H S T T G T A A A S AH T S H P M Q G R T T P S P E D S S W T D F F N P I S H P M G RG H Q A G R R (residues 53-219 of SEQ ID NO:4). Methods of using the antibodies to identify variant epitopes also are provided.