My daughter gave me a tomato plant this spring originating many years
back from my son-in-law's family - a somewhat typical Italian red
tomato, slightly plumper than a Roma . It's doing well with 7 or 8
normal looking tomatoes, but appears to have a 'sport', a single large
bulbous tomato off one branch bearing no resmblance to the others.

Is this common with tomatoes? If not, depending on how it looks at
maturity, is it something I should get excited about and pursue with a
local expert?

RHR