Pathologic and clinical features of Hodgkin lymphoma--like posttransplant lymphoproliferative disease

Because of its rarity, pathologic and clinical features of Hodgkin lymphoma-like posttransplant lymphoproliferative disorder (HL-like PTLD) are not well understood, and it is unclear whether its biological behavior is more closely related to classical Hodgkin disease or to monomorphic B-cell PTLD. The authors compared 6 cases of HL-like PTLD with 5 cases of monomorphic B-cell PTLD for differences in histology, immunophenotype, and clinical behavior. Histologically, all cases of HL-like PTLD resembled classical HL with typical Reed-Sternberg (RS) cells and a cellular background mimicking mixed cellularity subtype. CD45 was absent on RS-like cells, but the expression pattern of B-cell-associated markers Oct-2 and BOB.1 resembled monomorphic B-cell PTLD. Whereas Epstein-Barr virus early RNA expression is normally restricted to RS cells of classical HL, it was expressed in both RS-like cells and background lymphocytes in HL-like PTLD. Although all patients diagnosed with monomorphic B-cell PTLD show no evidence of disease following treatment, half of the patients with HL-like PTLD relapsed or died, indicating a more aggressive clinical behavior. The findings suggest that HL-like PTLD represents a distinct clinicopathologic entity with an aggressive clinical course.