To better define the spectrum of lymphomas that contain this translocation, we have analyzed 70 cases of non-Hodgkin's lymphoma (NHL) for expression of the t(2;5)-derived NPM/ALK chimeric message by reverse transcriptase-polymerase chain reaction (RT-PCR).     ///    "Using a previously described set of oligonucleotide primers, NPM/ALK chimeric transcripts were detected in 21 of 22 cases that contained the t(2;5) by cytogenetic analysis and in 10 of 48 cases that either lacked evidence of the t(2;5) or had unsuccessful cytogenetics. "    ///    "The NPM/ALK-expressing cases were not confined to NHLs with anaplastic morphology and included 15 ALCLs, 6 immunoblastic lymphomas, and 10 diffuse large-cell lymphomas. "    ///    "In all but 1 case, the NPM/ALK PCR products were of identical size and sequence, suggesting that the genomic chromosome breaks are clustered in a single intron in both NPM and ALK. "    ///    "Moreover, only slightly greater than half of the cases with anaplastic morphology and 59% of CD30-expressing cases were NPM/ALK positive. "