From:
dr_bruce_williams
Date: 2002-06-17 21:44:00 UTC
Subject: Re: Thymoma (?) Update...chemotherapy??
--- In Ferret-Health-list@y..., "drlambson" <drlambson@y...> wrote:
> We started him on Prednisone two Saturdays ago (.2ml 2x daily) and
> took another chest x-ray last Saturday. The mass has shrunk, and
> there is definitely more room for his lungs. I was under the
> impression that a thymoma would not be responsive to Prednisone,
and
> that really the only course of action would be radiation therapy or
> surgery. I suppose it could mean we're dealing with lymphoma? We
did
> a CBC on Sherlock today and will receive the results tomorrow. The
> vet would like to begin chemotherapy tomorrow if the CBC looks
good.
> Can anyone advise what the pros/cons of chemotherapy are? I know
it's
> not so bad for them as it is for humans, but he's so old I don't
want
> to hurt by trying to help.
Although I haven't seen either the lab report or the slides, the
diagnosis of thymoma, a very rare neoplasm in ferrets is not easily
done by fine needle aspirate, and both reported cases (actually, I've
seen one as well) were diagnosed at necropsy from a section of
tisue. Thymic lymphoma is a neoplasm composed totally of
lymphocytes, and thymoma is composed of epithelial cells (the
structural cells of the thymus), but by virtue of being in the
thymus, there will also be many many lymphocytes as well (the thymus
is a site where lymphocytes mature.) Hence, both neoplasms would
look pretty much identical on a fine needle aspirate, and only a
tissue section would definitively tell them apart.
The fact that it is responding well to the prednisone is much more
suggestive of lymphoma, as thymomas generally won't respond to it.
The use of prednisone as a chemotherapeutic agent is a relatively
benign approach in which the potential good far outweighs any
possible side effects. Ferrets are fairly resistant to the side
effects of prednisone which we seen in other species, and only at the
highest doses will you ever see gastric ulcers. However, continued
growth of a mass in the chest is not long compatible with life, so
you really have little choice here.
With kindest regards,
Bruce Williams, dVM