Extramedullary plasmacytoma of the oropharynx producing kappa-type Bence-Jonas protein.

A case of extramedullary plasmacytoma in the oropharynx of a 41 year-old woman is reported. Histologically, the tumor was plasmacytoma consisting mainly of matured plasma cells and showing a deposit of amyloid in the interstitial structure. Immunoelectrophoretic studies of the concentrated urine specimen revealed a kappa-type Bence-Jones protein even though there was no increase in blood M-protein. Lineac electron radiation of 5,100 rad was given over a period of eight weeks but no effect was noted. After the tumor was surgically removed, follow up of the patient was made for 2 years without evidence of recurrence or metastasis.