This is a quote from "The Secret Life of Walter Mitty", and it is a made-up term. He is not a skilled surgeon, so he made up the term obstreosis (a word that does not even exist), duct is like a passage, the same way as tract. So this "disease" makes no sense and does not exist.
The first sentence uses 'in greeting' redundancy, as 'to bow' means to greet someone in a very polite, formal way.
Revising, Reviewing, Editing...
Please vote my answer branliest! Thanks.
