The Collaborative International Dictionary of English v.0.48:

malignant anemia \malignant anemia\ n. (Med.)
   A chronic progressive anemia of older adults, thought to
   result from a lack of intrinsic factor (a substance secreted
   by the stomach that is responsible for the absorption of
   vitamin B-12); also called pernicious anemia.
   [WordNet 1.5]

WordNet (r) 3.0 (2006):

pernicious anemia
    n 1: a chronic progressive anemia of older adults; thought to
         result from a lack of intrinsic factor (a substance
         secreted by the stomach that is responsible for the
         absorption of vitamin B12) [syn: pernicious anemia,
         pernicious anaemia, malignant anemia, malignant
         anaemia]