response 25 of 31:

Mar 4 01:41 UTC 2006

Histiocytosis X is now called Langerhans Cell Histiocytosis (LCH).  Langerhans
cells are part of the immune system and are distant cousins of lymph cells,
and they tend to travel around the body.  If this is a benign case, it means
they caught it at a very early stage before there were many symptoms, and it
will be easier to treat and have a much better chance of success.  It can show
up in various ways - rash, coughing, digestive problems, thirst, depending
on the location, similar to lymphoma.  Some types progress very slowly and
can go away by themselves.  

There are other types of histiocytosis that don't affect Langerhans cells.
They are relatively rare (1 in 1 million) and also nonmalignant.  There is
a third category that is malignant.

The LCH is classified as to how many places are affected.  The earliest stage
is just skin.

There is one form where the symptoms are just due to a reaction against some
infection, which might explain the antibiotics.  Reactive hemophagocytic
syndrome.  It often clears up by itself but if severe it is treated with
chemotherapy.  This sounds like what is happening here.  

Look up eMedicine - histiocytosis, for a lot more facts that even I can
understand.

There is also sinus histiocytosis, which can go away by itself but may be
treated if the symptoms are severe, such as swollen lymph nodes.

May be caused by viruses, immune system dysfunction, etc.

There are 34 large pages (at 1024 text resolution with lynx).

It can be treated with corticosteroids (prednisone) and other drugs similar
to what is used for lymphoma (one of them comes from the Vinca plant which
is related to periwinkle flowers, vinca minor) that stop cells from dividing,
or with cyclosporine, which blocks the immune response.  They might give the
drugs every other week or every month for 1 to 4 months, maybe a combination
of three drugs, depending on the symptoms. They are relatively well tolerated
and the rate of complete remission ('cure') is very high even if it has
spread.

Drugs they might use are vinblastine and doxorubicin, both of which interfere
with cell division or DNA.  Cases that are not cured in this way sometimes
respond to thalidomide, which blocks the production of certain chemicals by
cells.

What are the symptoms that led to the diagnosis?

response 27 of 31:

Mar 4 15:51 UTC 2006

tod plesco for soopreme cort!

response 29 of 31:

Mar 5 12:55 UTC 2006

More reading, in an Immunology textbook, reveals that, if this is indeed
Langerhans cell histiocytosis, it is due to over production of Langerhans
cells, which reside in the skin.  They are a subtype of dendritic cells. 
Dendritic cells and lymph cells and a couple other types of cells are formed
from one branch of blood stem cells (the other branch forms red blood cells
and a few other things), and their job is to gobble up bacteria and viruses
and digest them into smaller pieces and put the pieces on their surface, where
the lymph cells see them and become activated to attack other cells with
viruses in them.  When they find a virus they migrate to the lymph nodes and
from there to all over the body.

If this is localized (benign) they have not migrated.  If it is not cancer,
they have not mutated (unlike lymphoma) but are just being overproduced for
some mysterious reason, maybe due to a viral infection that triggered this.
Since they have not mutated, they only live for a finite number of days
(cancer cells can be immortal) and then die naturally, which is probably why
this sort of disease can often clear up by itself.   But you can treat it with
the same sort of drugs as cancer, which stop cells from dividing.

They adjust the frequency of the drugs depending on the response to them.

response 31 of 31:

Mar 5 14:06 UTC 2006

Same thing as Langerhans Cell Histiocytosis, localized probably on the skin.
Is there a rash?  Fever due to the immune system being overactive?  How did
you know he was sick in the first place?