aristotle - 12:46 am on Dec 29, 2012 (gmt 0)
No, it looks like every few days they pick their showcase list and that list is attached to all their articles that get published for the next few days. Being a news site, the number of articles every day is quite large.
In that case a large majority of the 90,000 backlinks will come from pages with mostly unrelated content, and all links to the same page on your site will have the same anchor text. This clearly could have caused your site to get hit by Penguin, especially since Penguin has some major defects that have led to many mistakes in which sites it has affected.
One nice thing about Google's disavow tool is that you don't have to actually remove the questionable links, but only disavow them, so that your site can still get traffic from them.
In my opinion, your potential reward is greater than your potential risk if you disavow these 90,000 backlinks