There are only a few simple rules about italicizing foreign words, and they make pretty good sense.
Basically, italicize the foreign word the first time it appears, but not every time after that— if it is used frequently. More details below.
Foreign words can help convey a distinct meaning to our stories. Some words, like these, do not have a clear translation.
Find more of these gems in the book: Lost in Translation: An Illustrated Compendium of Untranslatable Words from Around the World by Ella Frances Sanders.