ALK-positive plasmablastic B-cell lymphoma with expression of the NPM-ALK fusion transcript: report of 2 cases.
While most anaplastic lymphoma kinase (ALK)-positive non-Hodgkin lymphomas (NHLs) are of T-cell lineage, a small number of B-lineage tumors with plasmablastic morphology and expression of the full-length ALK protein have been described in the literature. All of these reported tumors lacked the NPM-ALK fusion transcript. There is controversy regarding the existence of ALK fusion-positive B-cell NHL, with many investigators contending that ALK fusions are expressed uniquely in T- or null-cell lymphomas. Here we describe 2 well-characterized cases of ALK-positive B-cell lymphoma expressing the NPM-ALK fusion. Both tumors occurred in pediatric patients and showed poor response to chemotherapy. Each had plasmablastic morphology, showed immunoglobulin A restriction, and was ALK positive and CD30- by immunohistochemistry. One tumor showed the t(2;5)(p23;q35) chromosomal translocation by conventional cytogenetics. Both were positive for NPM-ALK by reverse transcriptase-polymerase chain reaction. Thus, ALK-positive plasmablastic B-cell lymphomas are more heterogeneous at the molecular level than previously recognized.
Onciu
Mihaela
M
Department of Pathology, St Jude Children's Research Hospital, 332 N Lauderdale St, Memphis, TN 38105, USA. mihaela.onciu@stjude.org
Behm
Frederick G
FG
Downing
James R
JR
Shurtleff
Sheila A
SA
Raimondi
Susana C
SC
Ma
Zhigui
Z
Morris
Stephan W
SW
Kennedy
Wren
W
Jones
Sandra C
SC
Sandlund
John T
JT
D000293:Adolescent; D000077548:Anaplastic Lymphoma Kinase; D002648:Child; D006801:Humans; D016393:Lymphoma, B-Cell / Q000235:genetics* / Q000378:metabolism* / Q000473:pathology; D008297:Male; D010950:Plasma Cells / Q000473:pathology; D011505:Protein-Tyrosine Kinases / Q000235:genetics* / Q000378:metabolism*; D020794:Receptor Protein-Tyrosine Kinases
C107023:p80(NPM-ALK) protein; C000626173:ALK protein, human; D000077548:Anaplastic Lymphoma Kinase; D011505:Protein-Tyrosine Kinases; D020794:Receptor Protein-Tyrosine Kinases