THE DETECTION OF ACQUIRED-IMMUNODEFICIENCY-SYNDROME ASSOCIATED KAPOSI-SARCOMA CELLS IN PLEURAL EFFUSION BY CD34 IMMUNOSTAIN

Background. Acquired immunodeficiency syndrome (AIDS)-associated Kapos i sarcoma (KS) cells have not been reported in pleural effusions. This study identifies the effusional form of AIDS-KS cells with the CD34 a ntibody, a newly recognized marker for vascular neoplasia. Methods. In the pleural effusion of a patient with AIDS and biopsy proven pulmona ry KS, the authors found bizarre amoeboid cells. Parallel sections fro m the cell blocks of the pleural effusions from the index patient and six other patients with AIDS were immunostained for cytokeratin, CD68, leukocyte common antigen (LCA), Factor VIII:R, and CD34. Results. The atypical cells were not observed in the pleural effusions of the othe r six patients with AIDS. The atypical cells were positive for CD34 (4 +) and Factor VIII:R (1+) but were negative for cytokeratin, CD68, or LCA, which were expressed by mesothelial cells, macrophages, and lymph ocytes, respectively. The expression for CD34 and Factor VIII:R was li mited to a sharply delineated perinuclear region in the cytoplasm, cor responding to the erythrocyte-containing intracytoplasmic space of the atypical cells on the filter. Conclusion. In conclusion, the erythroc yte-containing intracytoplasmic space within the atypical cells most l ikely represents the intracytoplasmic lumina of the AIDS-KS endothelia l cells and the CD-34-positive atypical cells represent the effusional form of the AIDS-KS cells.