Current morphologic and immunophenotypic overlaps of true ALCLs and anaplastic large B-cell lymphomas with classic Hodgkin disease.

The REAL classification refers to the overlapping neoplasms as ALCL–HD-like because they cannot, because of missing morphologic and immunophenotypic criteria, be allocated to one of the established lymphoma entities. The overlap between ALK⁺ ALCL and Hodgkin disease has disappeared with the availability of monoclonal antibodies to ALK protein, which strongly stain the tumor cells of all cases of ALCL with a rearranged ALK gene but consistently fail to stain Hodgkin and Reed-Sternberg cells of Hodgkin disease.