Intracellular Ig identification on paraffin-embedded solitary plasmacytoid proliferation: a routine method to define the biological nature of plasma cells.

The difficulty to recognize morphologically the biological nature of the exuberant plasma cell proliferations is known by every pathologist. Therefore, an immunohistochemical method has been applied to routine paraffin-embedded sections of biopsies from 26 patients suspected to bear a solitary plasmacytoma. The method has allowed to distinguish between monoclonal (likely to be neoplastic) and polyclonal cases (likely to be reactive).