Diagnostic use of the immunoperoxidase technique for cutaneous plasma cell lesions.

Distinguishing cutaneous neoplastic plasma cell infiltrations from inflammatory reactions containing predominantly plasma cells can present diagnostic problems when conventional histological techniques are used. Eight cases of cutaneous lesions, composed almost exclusively of plasma cells, are presented. We discuss the use of the peroxidase-antiperoxidase technique to distinguish malignant plasma cells that produce only one type of immunoglobulin from benign lesions that are polyclonal and produce several immunoglobulins.