<< I've been reading all night about possible reasons but I have fallen short
of any reasonable answer.

Thank you for your help. >>

Have you been to a vet?  Food allergy?  Ringworm?  Fleas?

Candace
(take the litter out before replying by e-mail)

See my cats:
http://photos.yahoo.com/maccandace

"One does not meet oneself until one catches the reflection from an eye other
than human."  (Loren Eisely)

Patterned hair loss can be a sign of infection, among other things.
Get the cat to the vet asap.

-L.

I haven't seen the hair loss you seem to be describing, but in case you
actually meant the hair loss to have started from the base of the tail
(nearest the body), it could be the following:

If the cat is intact (not neutered), he may have "stud tail."

If neutered, he may have developed an allergy to fleas.

Either way (or neither way), you need to consult your vet.

Let us know the outcome.

Sharon Talbert
Friends of Campus Cats