The 2017 MeSH Tree Hierarchy(2017MeSHTree.pdf) contained originally 57842 categories. Below is A list of articles named after MeSH categories, after excluding:
categories with places names like (California, Germany, Australia, etc)
categories with publication types like (Atlases, Bibliography, Biography, Book reviews, etc)
duplicates
categories with the suffix "as topic" like (meta analysis as topic, statistics as topic, clinical trials as topic, etc)
articles already present in Wikipedia (as of April 2017)