Molecular analysis of the NPM-ALK rearrangement in Hodgkin's disease.

The fusion gene NPM-ALK occurs in a subset of anaplastic large cell lymphomas (ALCLs), as a result of a chromosomal translocation, t(2;5) (p23;q35). It has been suggested that Hodgkin's disease (HD) and ALCL share a common histogenesis because of pathological and phenotypical similarities. In order to check this hypothesis, reverse transcriptase-polymerase chain reaction (RT-PCR) was performed to detect the hybrid NPM-ALK gene in 30 tumour samples, including 22 lymph node biopsies from HD and eight ALCL specimens. The threshold level of sensitivity was shown to reach at least 1/10(4) by dilution experiments using cell lines as positive and negative controls. The expected 177 bp product indicative of the NPM-ALK rearrangement was identified in Karpas 299 and SUDHL-1 cell lines and in two out of eight ALCLs. The 22 HD cases were negative, even after two successive tests. Thus, since the ALCL-specific genetic alteration was absent in our series of HD cases, the present study does not support the hypothesis that HD and ALCL are histogenetically related entities.