Combined cytomorphologic and immunophenotypic analysis in the diagnostic workup of lymphomatous effusions

OBJECTIVE: To analyze the results of cytomorphology and immunophenotyping i n 54 patients with lymphomatous effusions. STUDY DESIGN: We report the results of cytomorphology and immunophenotyping in 54 patients with lymphomatous effusions. Twenty-three of tile 54 had a previous diagnosis of NHL. In the remaining 31 patients, lymphomatous invol vement was clinically suspected. RESULTS: Thirty-three lymphomatous effusions were positive for involvement by NHL. Twenty-one of these 33 patients (64%) had a previous diagnosis of N HL. Of the remaining 12 patients with newly diagnosed NHL, 11 had high grad e lymphoma, and one had follicular center lymphoma. Twenty effusions were c onsidered to be reactive; only two of these patients had NHL. One effusion revealed involvement by a previously unknown carcinoma. We observed seven f alse negative results if only one of bell? methods was considered. A high g rade NHL was not diagnosed by immunophenotyping in one ease, and six cases of low grade NHL could not be detected by cytomorphology. The combined stra tegy of cytomorphology and immunophenotyping had a sensitivity of 100% and specificity of 100% in our study, confirmed by followup studies. CONCLUSION: Both methods have shown difficulties in the examination of lymp homatous effusions. Cytomorphology has problems distinguishing reactive eff usions from low grade NHL. The detection of high grade NHL by immunophenoty ping is difficult. However, both methods together offer the advantage of du al staining ability and are most helpful in distinguishing clonal lymphomat ous from reactive effusions.