Frequent CD7 antigen loss in aggressive natural killer-cell leukemia: a useful diagnostic marker.
BACKGROUND
Aggressive natural killer-cell leukemia (ANKL) is a rare neoplasm characterized by systemic proliferation of NK cells. However, the differential diagnosis of NK lymphoproliferative disorders is difficult because of the absence of a distinct diagnostic hallmark. Therefore, to identify diagnostic markers for ANKL, we analyzed the clinical data and laboratory findings obtained for 20 patients with ANKL.


METHODS
From January 2000 to July 2007, 20 patients were diagnosed with ANKL on the basis of bone marrow studies. We retrospectively analyzed the clinical features and laboratory findings, including the complete blood count, Epstein-Barr virus status, immunophenotype, and the cytogenetic results.


RESULTS
The subjects included 6 women and 14 men (median age, 44 yr; range, 2-70 yr). Cytogenetic studies were performed in 18 patients, and karyotypic abnormalities were observed in 9 patients (50%). None of the cytogenetic abnormalities were constantly observed in all the patients. However, 6q abnormalities were observed in 4 patients (4/18, 22%). The immunophenotype of the leukemic NK-cells was cytoplasmic CD3(+), surface CD3(-), CD16/56(+), CD2(+), and CD5(-). Notably, the CD7 antigen was absent in 10 patients (50%). When the CD7 loss was combined with cytogenetic abnormalities, clonal markers could be identified in 75% of the ANKL cases.


CONCLUSIONS
The CD7 antigen loss was frequently observed in our series of ANKL patients. In conjunction with the cytogenetic findings, this characteristic immunophenotypic finding can serve as a reliable marker for the timely diagnosis of ANKL. Therefore, immunophenotypic analysis of CD7 expression should be included in the diagnosis of NK cell neoplasms.
Yoo
Eun-Hyung
EH
Department of Laboratory Medicine & Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
Kim
Hee-Jin
HJ
Lee
Seung-Tae
ST
Kim
Won-Seog
WS
Kim
Sun-Hee
SH
D000293:Adolescent; D000328:Adult; D000368:Aged; D019011:Antigens, CD7 / Q000032:analysis*; D014408:Biomarkers, Tumor / Q000032:analysis*; D001772:Blood Cell Count; D002648:Child; D002675:Child, Preschool; D003582:Cytogenetics; D005260:Female; D004854:Herpesvirus 4, Human / Q000302:isolation & purification; D006801:Humans; D016130:Immunophenotyping; D007621:Karyotyping; D054066:Leukemia, Large Granular Lymphocytic / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies
D019011:Antigens, CD7; D014408:Biomarkers, Tumor