fidencio@jerk ~ $ port deps gtk2 +no_x11+quartz
Full Name: gtk2 @2.24.3_0+no_x11+quartz
Build Dependencies:   pkgconfig
Library Dependencies: atk, pango, gdk-pixbuf2
Runtime Dependencies: shared-mime-info


Looking for atk deps, we have:

fidencio@jerk ~ $ port deps atk
Full Name: atk @1.32.0_0
Build Dependencies:   pkgconfig, gtk-doc
Library Dependencies: glib2, gettext, libiconv



And looking for gtk-doc deps ...

fidencio@jerk ~ $ port deps gtk-doc
Full Name: gtk-doc @1.16_0+python27
Build Dependencies:   gnome-doc-utils, pkgconfig, glib2
Library Dependencies: rarian, libxml2, perl5, docbook-xml, docbook-xsl, python27
Runtime Dependencies: py27-libxml2


And, finally, looking for gnome-doc-utils

fidencio@jerk ~ $ port deps gnome-doc-utils
Full Name: gnome-doc-utils @0.20.4_0
Build Dependencies:   intltool, pkgconfig
Library Dependencies: gettext, libxslt, py27-libxml2, python27
Runtime Dependencies: docbook-xml, docbook-xsl, rarian, iso-codes

libxslt is Library dependency of gnome-doc-utils