Luschka's tonsil vs nasopharyngeal tonsil

Luschka's tonsil

noun

  • Synonym of adenoid. 

nasopharyngeal tonsil

noun

  • Synonym of adenoid. 

How often have the words Luschka's tonsil and nasopharyngeal tonsil occurred in a corpus of books? (source: Google Ngram Viewer )