For LyX to work you need to install some kind of TeX distribution. See the
print/texlive-* ports in the ports tree.

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As of version 2.0.0, LyX depends on the textproc/mythes ports for
thesaurus support. Even though the LyX port depends on textproc/mythes,
it is up to the user to install the thesaurus ports for her languages
of preference.