A systematic approach to the immunohistologic classification of lymphoproliferative disorders.

From the study of over 3,000 immunologically well characterized cases, we have developed a systematic approach for the immunohistologic evaluation of lymphoproliferative disorders (LPD). By using a basic screening panel of antibodies on fresh-frozen sections, LPD can be reliably immunophenotyped. Fourteen patterns of immunoreactivity have been identified that can be used in differential diagnosis and the establishment of the correct diagnosis. A comprehensive table has been developed for systematically recording for each case the results of immunohistologic evaluation of fresh-frozen sections. The information recorded is easily computerized for later studies of large numbers of cases. We also propose a strategy for the further characterization of rare cases that are not easily defined with the basic screening panel of immunologic reagents. The proposed systematic approach allows the rapid recognition of the predominant immunologic pattern, the determination of the differential diagnoses, and the establishment of the correct diagnosis. In many cases, the final diagnosis can be predicted on the basis of patterns of immunoreactivity in the fresh-frozen section prior to the evaluation of the paraffin-embedded histologic material. Moreover, this systematic approach may provide an additional method to classify LPD more precisely and reproducibly.