Bauhinia purpurea--a new paraffin section marker for Reed-Sternberg cells of Hodgkin's disease. A comparison with Leu-M1 (CD15), LN2 (CD74), peanut agglutinin, and Ber-H2 (CD30).

Thirty-three cases of Hodgkin's disease (thirteen nodular sclerosis, four diffuse, lymphocyte predominance, and sixteen mixed cellularity) were studied with Bauhinia purpurea (BPA), peanut agglutinin (PNA), anti-Leu-M1, LN2, and Ber-H2 by the avidinbiotin-peroxidase complex (ABC) method in paraffin sections. Reed-Sternberg (RS) cells and variants were stained positively with one or more of the reagents in all cases. BPA staining was positive in 32 of 33 cases (97.0%), PNA staining was positive in 23 of 33 cases (69.7%), Leu-M1 was positive in 13 of 33 cases (39.4%), LN2 was positive in 14 of 33 cases (42.4%), and Ber-H2 was positive in 24 of 33 cases (72.7%). Many RS cells were stained moderately to strongly and were readily recognized in 31 cases (96.9%) of BPA+, 10 (43.5%) of PNA+, 8 (61.5%) of Leu-M1+, 6 (42.9%) of LN2+, and 22 (91.7%) of Ber-H2+ cases; in the remaining positive cases, the RS cells were found only after careful searching. Three staining patterns were recognized: paranuclear, diffuse cytoplasmic, and membranous. These three patterns were obtained with all markers except for LN2. LN2 showed diffuse cytoplasmic staining in most of the positive cells, and a few cells showed paranuclear deposits. BPA reactivity was not affected by formalin fixation or paraffin embedding. Except for RS cells, BPA also showed dense cytoplasmic staining reaction with macrophage-histiocytes. Sixty cases of non-Hodgkin's diffuse lymphomas (30 T- and 30 B-cell origin) were also studied. Tumor cells were not stained with BPA, PNA, and Leu-M1, but stained positively with LN2 in six T-cell lymphomas and thirteen B-cell lymphomas, and with Ber-H2 in six T-cell lymphomas and one B-cell lymphoma. In conclusion, to facilitate the detection of RS cells and related variants in paraffin sections, BPA can be accepted as a useful marker due to its high-detection rate, reproducible staining pattern, and resistance to fixatives.