Abstract

BACKGROUND
The natural killer cell antigen CD56 (NCAM) is a member of the immunoglobulin superfamily and is expressed on neurons, astrocytes, and Schwann cells. Recently, it has been reported that CD56 expression is detected on plasma cells of multiple myeloma by flow cytometry.
METHOD
In this study, to test the diagnostic usefulness of the anti-CD56 antibody for plasma cell neoplasm on paraffin-embedded materials, we performed immunohistochemical staining of samples from 19 patients with plasma cell neoplasms. These cases included 14 cases of multiple myeloma, 3 cases of solitary plasmacytoma of the bone, and two cases of extramedullary plasmacytoma.
RESULTS
The neoplastic plasma cells from 68 % of the patients with plasma cell neoplasms expressed CD56 highly. CD56 was expressed in all three cases of solitary plasmacytoma of the bone and one of two extramedullary plasmacytoma, and nine out of 14 multiple myeloma cases. In contrast, reactive plasma cells from the 18 patients with miscellaneous lesions were completely negative for CD56.
CONCLUSIONS
CD56 is aberrantly expressed on the neoplastic plasma cells, and it may be used as a useful marker for the diagnosis of plasma cell neoplasms in paraffin-embedded tissues.

• Keywords: CD56;Plasma cell;Multiple myeloma;Plasmacytoma;Immunohistochemistry;