In 1920, I had occasion to describe two rather rare tumors of the type first depicted by Cruveilhier1 under the name "tumeurs perlées." Since then, the observations which follow, as well as the articles of Cushing2 and Horrax,3 have cleared up many doubtful points in my original description.
The cases reported in 1920, the ones detailed by Cushing and Horrax, and those which follow, all belong to the class known to Bostroem4 as piale Epidermoide. They have also been termed "tumeurs perlées" and "cholesteatomas." None of these terms is satisfactory, for various reasons. There are, for example, the pearly tumors so often found in the lateral ventricle of the horse, which have nothing in common with the growths under discussion except the glistening pearly surface. The term cholesteatomas is no less objectionable because often cholesterin is not present, and furthermore, tumors of the breast, testicle, etc.,