Sensitivity and specificity of immunostaining in the diagnosis of mantle zone lymphoma.

The diagnosis of mantle zone lymphoma is sometimes difficult to make solely on the basis of morphology because the mantle zone pattern may be present in other disorders such as benign mantle zone hyperplasia, follicular center cell (FCC) lymphomas, and Castleman disease. To distinguish mantle zone lymphoma from the other disorders mentioned previously, the authors performed immunoperoxidase studies on B-5-fixed, paraffin-embedded sections or cryostat sections of lymph nodes from nine patients with a diagnosis of mantle zone lymphoma. The results then were compared with the immunostaining pattern seen in FCC lymphomas and various benign lymphoid hyperplasias. A monoclonal proliferation of mantle zone cells, as shown by staining for immunoglobulin light chains, was noted in the mantle zones and interfollicular areas in all six cases from which cryostat sections were available. The cells in the residual follicular centers uniformly had a polyclonal light chain marking pattern. Two novel monoclonal antibodies (LN-1 and LN-2) that identify FCCs and B-cells in B-5-fixed, paraffin-embedded tissues also were used in this study. Of the six cases in which the monoclonal antibodies could be used, the cells in the residual follicles were uniformly LN-1 positive, LN-2 positive, while the mantle zone and interfollicular cells were almost completely LN-1 negative, LN-2 positive. The data suggest that mantle zone lymphomas are a distinctive neoplasm of monoclonal B-cells of non-FCC origin. The authors conclude that immunostaining is a sensitive technic for identifying a malignant neoplasm of B-cells in the mantle zone and interfollicular areas. In addition, the method is relatively specific and useful for distinguishing mantle zone lymphoma from similar-appearing disorders such as benign mantle zone hyperplasias and certain FCC lymphomas.