LYMPHOCYTE-PREDOMINANT HODGKINS-DISEASE - AN IMMUNOHISTOCHEMICAL ANALYSIS OF 208 REVIEWED HODGKINS-DISEASE CASES FROM THE GERMAN HODGKIN STUDY-GROUP

There is wide consensus that lymphocyte predominance Hodgkin's disease (LPHD) represents a distinct clinicopathological entity of B-cell ori gin. However, inconsistent results of immunophenotyping studies and lo w confirmation rates among multi-center trials pose the question of wh ether LPHD really expresses heterogeneous marker profiles or whether i t represents a mixture of morphologically similar entities. Among 2,83 6 cases reviewed by the German Hodgkin Study Group, immunophenotyping was performed on 1) cases classified or confirmed as LPHD by the refer ence panel (n = 104) or 2) cases not confirmed as LPHD but classified as classical HD (cHD) within the reference study trial (n = 104). In m ost cases, immunohistochemistry revealed a phenotype either LPHD-like (CD20(+), CD15(-), CD30(-), CD45(+)) or cHD-like (CD15(+), CD30(+), CD 20(-), CD45(-)). In 27 cases, the immunophenotype was not fully conclu sive. Additional markers for Epstein-Barr virus and CD57 and in situ h ybridization for mRNA light chains allowed for a more clear-cut distin ction between LPHD and cHD. However, in 25 of 104 cases, immunohistoch emistry disproved the morphological diagnosis of LPHD of the panel exp erts, whereas 13 cases originally not confirmed as LPHD showed a LPHD- like immunopattern. Immunohistochemically confirmed LPHD cases showed a significantly better freedom front treatment failure (P = 0.033) tha n cHD; this was not observed in the original study classification base d only on morphology (P > 0.05). Significantly better survival for LPH D cases improved from P = 0.047 (original study classification) to P = 0.0071 when classified by immunohistochemistry. Our results show that LPHD is a more immunohistochemical rather than a purely morphological diagnosis. Immunophenotyping of HD biopsies suspected of being LPHD i s mandatory when a modified therapy protocol, that is, one different f rom those used in cHD, is discussed.