I am not too sure you
will be able to tell the tissue of origin here, but it is spleen. These
tumors can occur in many different organs, liver, spleen and bone marrow
being most frequent. The plasma cells in this lesion may be active, and
if so produce a monoclonal gamma globulin or portion of gamma globulin.
(Be sure you understand what is meant by an electrophoretic spike.)
On occasion no spike is seen in the serum and the reason is that the protein
being elaborated is so small that it is cleared in the urine.
Checking the urine for a gamma globulin spike is always a good idea in
plasma cell tumor.
The story here is simply
plasma cells. Essentially every cell in the field is a plasma cell.
As I try to emphasize above, it's the protein they are making that needs
to be watched and understood.
