CLL-like MBL has been so-named because of its close phenotypic resemblance with clinical CLL. Shared markers used in the diagnostic work-up include, beside CD5 and CD20, also CD23, low levels of surface Immunoglobulins (Ig) and Ig-related molecules (CD79b), and low to negative expression of FMC7.(4, 5) Further analyses have been performed to define specific protein expression that may distinguish MBL from CLL. One study evaluated 18 additional B-cell markers by flow cytometry in individuals with CLL, MBL, other B-cell lymphoproliferative disorders, and individuals without B-cell malignancy.(16) This analysis confirmed the distinct phenotype of CLL compared to other B-cell disorders, but found individuals with CLL and CLL-like MBL clustered together when an unsupervised analysis was performed. Expression of no specific protein was able to distinguish between CLL and CLL-like MBL.
