How can I use a xsl file to remove empty elements except if it is a mycol element?

Ex.:
Code:
<mytable>
<myrow>
<mycol><para align="right">Just for testing<para></para></para></mycol>
<mycol>anything <b></b>else</mycol>
</myrow>
<myrow>
<mycol></mycol>
<mycol></mycol>
</myrow>
</mytable>
In the example above I need to remove the <para></para> and the <b></b> empty elements and keep only the <mycol></mycol> elements.
Any idea?