Brief report: natural history of individuals with clinically recognized monoclonal B-cell lymphocytosis compared with patients with Rai 0 chronic lymphocytic leukemia.
OBJECTIVE
The diagnosis of monoclonal B-cell lymphocytosis (MBL) is used to characterize patients with a circulating population of clonal B cells, a total B-cell count of less than 5 x 10(9)/L, and no other features of a B-cell lymphoproliferative disorder including lymphadenopathy/organomegaly. The natural history of clinically identified MBL is unclear. The goal of this study was to explore the outcome of patients with MBL relative to that of individuals with Rai stage 0 chronic lymphocytic leukemia (CLL).


METHODS
We used hematopathology records to identify a cohort of 631 patients with newly diagnosed MBL or Rai stage 0 CLL. Within this cohort, 302 patients had MBL (B-cell counts of 0.02 to 4.99 x 10(9)/L); 94 patients had Rai stage 0 CLL with an absolute lymphocyte count (ALC) < or = 10 x 10(9)/L; and 219 patients had Rai stage 0 CLL with an ALC more than 10 x 10(9)/L. Data on clinical outcome were abstracted from medical records.


RESULTS
The percentage of MBL patients free of treatment at 1, 2, and 5 years was 99%, 98%, and 93%, respectively. B-cell count as a continuous variable (hazard ratio [HR] = 2.9, P = .04) and CD38 status (HR = 10.8, P = .006) predicted time to treatment (TTT) among MBL patients. The likelihood of treatment for MBL patients was lower (HR = 0.32, P = .04) than that of both Rai stage 0 CLL patients with an ALC less than 10 x 10(9)/L (n = 94) and Rai stage 0 CLL patients with an ALC more than 10 x 10(9)/L (n = 219; P = .0003).


CONCLUSIONS
Individuals with MBL identified in clinical practice have a low risk for progression at 5 years. Because B-cell count seems to relate to TTT as a continuous variable, additional studies are needed to determine what B-cell count should be used to distinguish between MBL and CLL.
Shanafelt
Tait D
TD
Mayo Clinic, Rochester, MN 55905, USA. shanafelt.tait@mayo.edu
Kay
Neil E
NE
Rabe
Kari G
KG
Call
Timothy G
TG
Zent
Clive S
CS
Maddocks
Kami
K
Jenkins
Greg
G
Jelinek
Diane F
DF
Morice
William G
WG
Boysen
Justin
J
Schwager
Susan
S
Bowen
Deborah
D
Slager
Susan L
SL
Hanson
Curtis A
CA
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001402:B-Lymphocytes / Q000473:pathology*; D005260:Female; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000097:blood* / Q000473:pathology; D018655:Lymphocyte Count; D008218:Lymphocytosis / Q000097:blood* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging