NPM-ALK gene rearrangements were detected in all RT-PCR, NPM-ALK-positive ALCL by Southern blot analysis.     ///    "To investigate the presence and the precise frequency of NPM-ALK gene products among ALCL and HD cases, a large and well-characterized panel of ALCL (n = 49) and HD (n = 72) cases was studied using multiple strategies including reverse transcriptase-polymerase chain reaction (RT-PCR), Southern blot analysis, and immunohistochemistry. "    ///    "Overall, 6 (3 T and 3 null) of 49 ALCL and 3 (2 nodular sclerosis and 1 mixed cellularity) of 72 HD showed the presence of NPM-ALK transcripts by RT-PCR. "    ///    "Our data show that NPM-ALK gene transcripts are identified in a subpopulation of ALCL, almost exclusively in T or null cell in origin, and in rare cases of HD. "