In 2008 the European Union relaxed its previously strict rules against the marketing of “imperfect” fruits and vegetables, but only on 26 varieties – not including tomatoes. At the time of the announcement, European Commission spokesman Michael Mann said “This is a happy day indeed for the curvy cucumber and the knobbly carrot, and other amusingly shaped fruits and vegetables.”
I haven’t found a specific explanation yet for the type of aberrant growth shown here. The closest I’ve found is that misshapen tomatoes (including “catfacing”) are caused by pollination during cool weather. This tomato was harvested today, so that doesn’t seem to be the likely root cause (no pun intended), more than six weeks since we’ve had any cool weather.
Another possibility is that the growth is simply a genetic throwback to heirloom tomatoes, when non-hybridized tomatoes weren’t perfectly shaped. Our judgement is that the growth does not affect taste or nutrition.
Anybody know the root cause for the appendage? (BTW: We know the reasons for the cracking and the green “shoulders”.)
albert vick 
Oh my! I thought you were kidding about the EU — but I can see that you aren’t.
http://www.dailymail.co.uk/news/article-1081329/Campaign-bring-curvy-cucumber-grows-EU-comes-pressure-relax-rules-sale-imperfect-fruit-veg.html
The most recent EU produce standards info I could find was 2009. Tomatoes are listed in three classes, and all three disallow “green backs” (I think they mean green shoulders) and any cracking more than a few CMs in length. I think the rigorous standards actually backfire, by driving hybridizers to pursue cosmetic quality over nutrition. Green “shoulders” are caused by extreme heat and scorching sun. The tomato fruit actually needs to be partially shaded by the plant’s foliage to minimize detrimental effects of sun scalding.