This morning I was looking through some cans in the garage and pantry and found that the S&W Premium Ready-Cut Diced Tomatoes cans was bulging. I sent an email contact to https://www.swfinefoods.com/ to see how they handle these sorts of situations.
Call 800- 252-7033
Monday – Friday, 9:00 am to 5:00 pm ET
Write
S&W Fine Foods Consumer ServicesP.O. Box 193575San Francisco, CA 94119-3575

The cans I have are Best By Mar 31 09
With a code 5B 6228H8 19:54

Then I did some research and found the following.

Cans bulge primarily because of a potentially deadly bacteria fermenting in it, which causes a type of food poisoning known as Botulism. DO NOT PURCHASE A CAN WITH BULGES. Botulism can kill you.

botulism /bot·u·lism/ (boch´ah-lizm) an extremely severe type of food poisoning due to a neurotoxin (botulin) produced by Clostridium botulinum in improperly canned or preserved foods.

There is lots of info about this topic. They all say the same thing, do not purchase or eat a can that has expanded/bulged it could make you very sick or ill.