Trivial Trivia - taking trivia to new levels

[L Verge]

This is a question posed to our two super sleuths who seem to find assassination-related artifacts everywhere:

Rich and Jim - A tourism website for weird museums says that the Mutter Museum has a growth taken from John Wilkes Booth. What is it? The piece of thoracic tissue? The carbuncle removed by Dr. May that inspired the phrase "Mark of the Scalpel?" Are they both the same thing? If it is the carbuncle, why would Dr, May have kept it?

Blaine - Feel free to chime in on this also as our team physician here (or any other doctors we may have in the house).