In ups.com,
purred:
Hi - I need the help of a cat owner if possible. (one that has a cat
around them now would be great!) My cat had a bout with fibrosaurcoma
cancer over the past year and half that ended with a hopefulyl
curative amputation of one of her front legs. She has adapted well.

Here's my problem, diligently observing her my wife felt a tiny bump
in her other front leg. We both think that it maybe normal but we
have no other leg to feel to see if the bump is symetrical to her
other leg. Can someone check their cat and see if they also have this
small bump?

Its located in the back of the front leg about an inch above the
"thumb" pad, but below the elbow - directly in line with thumb pad. We
do have an appointment to bring her in to the vet later this week to
be sure but wanted to (hopefully) put my mind at ease by having
someone else verfiy this is actually normal.

Thanks in advance,
A concerned kitty owner

After reading your message, I felt around my desktop-kitty's (Mimi) front
legs. She has what appears to be callous like lumps about where you
describe. They are fur-covered, and move with the skin. Since Mimi doesn't
like her paws messed with, i went to check another cat (this one was
napping on the bed, and doesn't mind 'inspections' quite so much), and he
has the same.

Both cats are siblings, but not from the same litter.