. Author manuscript; available in PMC: 2010 Oct 25.

Published in final edited form as: Cytometry B Clin Cytom. 2010;78(Suppl 1):S10–S18. doi: 10.1002/cyto.b.20538

Table 2.

Overview of Studies that Reported the Frequency of MBL Among Outpatient Clinics, Excluding Familial-CLL Clinics

Authors, year (reference)	Country, study period, and study population	Laboratory tests and clinical evaluation	MBL Criteria	Frequency of MBL N (%)
Rawstron et al., 2008 (3)	United Kingdom Cohort 1: Outpatients with entirely normal blood counts Total n: 1520 Age: 62–80 years Male 630; female 890 Cohort 2: 1995–2000 Patients referred for current or previous lymphocytosis Total n: 2228 Age: 39–99 years	Flow cytometry Acquisition: 5 × 10⁵ events/sample Four color screening: CD5/CD19/k/λ Extended panel^a for cases with a k:λ ratio of >2.1:1 or <1:1 FISH PCR analysis for IGHV gene	B-cell count <5 × 10^9/L CLL-phenotype MBL: CD19⁺, CD5⁺, CD23⁺, CD20^weak, CD79b^weak, and either k or λ Ig light chains Non–CLL-phenotype MBL: light-chain–restricted CD19⁺ B-cells with CD5⁻ and strong CD20⁺ No history of cancer	Cohort 1 All MBL:105/1520 (6.9%) CLL-phenotype: 78/1520 (5.1%) Non-CLL-phenotype: 27/1520 (1.8%) Cohort 2 CLL-phenotype: 309/2228 (13.9%)
Ghia et al., 2004 (15)	Italy Study period: “20 months” Outpatients from three clinics outside Turin; referred for routine blood tests; normal blood cell counts; and had no history or suspicion of malignancy Total n: 500 Age: > 65 years Male 231; female 269	Flow cytometry Acquisition: ≥2 × 10⁵ events/sample Four color: CD5/CD19/k/λ for all 500 cases and CD5/CD20/CD79b/CD19 for 350 cases Extended panel for cases with CLL-like phenotype or unbalanced k:λ ratio^b: CD10, CD20, CD23, CD79b, IgM, IgD, IgG, FMC7 PCR analysis for IGHV, bcl-1, bcl-2 genes	Unbalanced k:λ ratio^b CLL-like MBL: CD20^low, CD23⁺, CD5^bright, FMC7⁻, CD10⁻, IgM^low, CD79b^low Atypical CLL-like MBL: CD20^high, CD23⁺, CD5^bright FMC7⁻, CD10⁻, IgM^low, CD79b^low Non–CLL-like MBL: CD20^high, CD23⁻, CD5⁻, FMC7⁺, CD10⁻, IgM^1+/low, CD79b⁺	All MBL: 32/500 (6.4%) Male/female: (7.4%)/(5.6%) k restricted (includes two biclonal MBLs): 25/500 (5.0%) λ restricted: 7/500 (1.4%) CLL-like: 22/500 (4.4%) Atypical CLL-like: 3/500 (0.6%) Non–CLL-like (includes 2 biclonal MBLs): 7/500 (1.4%)
Rawstron et al., 2002 (16)	United Kingdom Hospital outpatients with normal hematologic parameters; samples not sent to assess any malignancy; had not been seen at hematology, oncology, transplantation clinic; <24 h sample available Total n: 910 Age: > 40 years Male 425; female 485	Flow cytometry Acquisition: ≥2 × 10⁵events/sample Four color screening: CD20/CD76b/CD19/CD5; k/λ/CD19/CD5 Extended panel for cases with CLL-phenotype: CD19, CD5 or CD20; CD3/CD3; k/λ; CD5 or CD79b, CD20/CD79b; CD11a/CD23; IgM/CD38; CD10/CD22; IgG/CD27 PCR analysis for IGHV gene	Clonal B-cell cluster of minimum 50 cellular events CLL-phenotype MBL: CD20^low, CD5^bright, CD79b⁺, and abnormal Ig light-chain expression^c Non-CLL phenotype MBL: normal expression of CD5/20/79b and light chain restriction	All MBL: 41/910 (4.5%) CLL-phenotype: 32/910 (3.5%) Male/female: (4.9%)/(2.3%) Age: 40–59 (2.1%), ≥60 (5.0%); Non-CLL phenotype: 9/910 (1.0%)

Extended panel for lymphocytosis cases:CD19, CD3/CD3 (control), CD20/CD5, CD10/CD38, k/λ, FMC7/CD22, CD11a/CD23, IgM/IgD, IgG/CD76b and for cases with normal blood count: CD19, CD5, CD20/CD79b, FMC7/CD23.

unbalanced k:λ ratio: a k:λ ratio of >3:1 or <1:3.

abnormal Ig light-chain expression: a k/λ ratio of >4.0 or <0.5, or >25% lacking sIg.