Anaplastic large cell lymphoma (ALCL) is a distinct clinicopathologic variant of intermediate grade non-Hodgkin's
lymphomas (NHL) composed of large pleomorphic cells that usually express the
CD30 antigen and
interleukin (IL)-2 receptors, and is characterized by frequent cutaneous and extranodal involvement. With variable frequency ALCL bear the t(2;5)(
p23;q35)
chromosomal translocation that fuses the
nucleophosmin (NPM) gene on chromosome 5q35 to a novel
protein kinase gene,
Anaplastic Lymphoma Kinase (ALK), on chromosome 2p23. We determined the frequency of this translocation with a novel
DNA polymerase chain reaction (PCR) technique using 0.5 microgram of genomic
DNA, 5'-primers derived from the NPM gene and 3'-primers derived from the ALK gene and hybridization with internal probes. The presence of amplifiable
DNA in the samples was tested with the inclusion in the PCR reaction of
oligonucleotide primers designed to amplify a 3016-bp fragment from the
beta-globin locus. NMP-ALK fusion amplicons were detected using
DNA isolated either from all three ALCL cell lines tested, or from all four primary ALCL
tumors known to contain the t(2;5)(
p23;q35) translocation. Nested amplicons were detected by hybridization in 100% of specimens diluted 10(4)-fold and in 20% of those diluted 10(5)-fold. We subsequently examined archival genomic
DNA from 20 patients with ALCL, 39 with diffuse large cell, 2 with mantle cell, 20 with peripheral T cell, 13 with low-grade NHL, 31 with
Hodgkin's disease (HD), and 6 with
lymphomatoid papulosis. Fusion of the NPM and ALK genes was detected in three of 18 patients with ALCL who had amplifiable
DNA (17%, 95% confidence intervals 4% to 41%), but not in any patients with other NHL, HD, or
lymphomatoid papulosis. The amplicon sizes were different in all cell lines and patients reflecting unique genomic
DNA breakpoints. We conclude that with genomic
DNA-PCR the rearrangement of the NPM and ALK loci is restricted to patients with ALCL. Further studies are needed to determine the prognostic significance of the
NPM-ALK rearrangement, to determine whether its detection can aid in the differential diagnosis between ALCL.
Hodgkin's disease, and
lymphomatoid papulosis, and to establish the usefulness of the genomic
DNA PCR in the monitoring of
minimal residual disease in those patients whose
tumors bear the t(2;5).