I don't understand, I think it's the first time I see that. Perhaps because it breaks my design here.
I have 3 TD with text. For the first :
<td rowspan="1" colspan="2" style="color:#000000;font-size:23px;font-weight:bold;mso-line-height-rule: exactly;line-height: 26px;">blablabla<br /><span style="color:#03a859;">blablabla</span><br />blablabla</td>
It's ok, as for the last : size is the same for all email clients.
But for the second, displayed font size is not the same on Outlook 07/10/13 !
<td rowspan="1" colspan="2" style="font-size: 11px; text-align:left; color:#000000;mso-line-height-rule: exactly;line-height: 16px;">blablablabla<br />blablablabalbbl, blablablabablblabla.<br />Blablablablabla blabla blablablabla.</td>
It's ok on all email clients but this Outlook versions. Text is slightly bigger and so, I have to reduce its size, making the text difficult to read.
Did you ever had this problem?