pigmentation vs polychromasia

pigmentation

noun
  • Coloration of human, plant or animal tissue, especially by pigment. 

polychromasia

noun
  • A disorder in which there is an abnormally high number of red blood cells in the bloodstream as a result of their having been prematurely released from the bone marrow during blood formation. 

How often have the words pigmentation and polychromasia occurred in a corpus of books? (source: Google Ngram Viewer )