• Extramedullary plasmacytoma is a tumor consisting of myeloma cells but occurs outside the bone marrow .
The most commonly involved area is the back of the nose and throat (nasopharynx), and the sinuses may also
be involved. Eighty percent of cases involve the upper respiratory area.
Extramedullary plasmacytomas may also involve the stomach, small bowel, colon, urinary bladder, thyroid,
breast or the brain. Examination of the bone marrow is normal, and the patients have no lytic bone lesions or
M-protein in the blood or urine. If an abnormal protein is present, it should disappear after treatment.
Diagnosis of a plasmacytoma is made after a biopsy of the tumor. It is treated with large doses of radiation
therapy. Most patients are cured, but the disease may recur in a nearby area. The development of typical
multiple myeloma is uncommon.
What Causes It The cause is not known, although exposure to radiation may be a factor in some cases. Survivors of the atomic bomb explosions in Japan had an increased incidence of multiple myeloma.
There is little evidence that chemicals cause myeloma in humans, although some reports have linked multiple myeloma with benzene or asbestos. An increased risk of multiple myeloma has been recognized in farmers in several countries and has been noted in rubber workers, furniture workers and those exposed to pesticides. The number of cases is small, however, and more information is needed to confirm this association.
