CLL early in transformation often has bright CD20 and surface light
chains. At this time CD23 may be dim to negative but FMC7 is usually dim.
Furthermore, mantle cell lymphoma can have dim CD23. I've even seen CLL
with no evidence of transformation with CD20 and light chains that weren't
dim or with dim to negative CD23. They aren't that common but they happen.
The problem in diagnosing CLL compared to mantle cell in leukemic phase is
that no one antibody does the job. It requires a panel, clinical history
and morphology and the more data you have the better. One does not
absolutely need FMC7 in the panel but don't always count on CD23, CD20 or
surface immunoglobulin as a single indicator. We are hoping that cyclin D1
will be the answer but will have to see how good the various antibodies are
in detecting mantle cell (not necessarily the same as detecting the normal
cell product).
Maryalice
>Melissa --
>
>According to the FAB group (Bennett JM, et al, J. Clin. Pathol. 1989;
>42:567-584), the incidence at which FMC7 is positive in >30% of cells in
>intermediate lymphocytic lymphoma (ie, Mantle Cell lymphoma) is 40-80%; in
>CLL, it is 10-40%.
>
>Our lab here in Scottsdale does not use FMC7; our panel resembles what Hugh
>Johnson has listed in his message earlier. We found that the addition of CD23
>sometime ago has facilitated identification of early (leukemic) presentations
>of MCL (CD5+/CD23-). These cases probably account for as many as 5-10% of our
>clonal B cell lymphoid leukemia patients. I would, however, add something to
>what Maryalice and Hugh have stated: the relative *intensity* of sIg and CD20
>expression can be extremely helpful in distinguishing between MCL and CLL. MCL
>(and other NHL) are typically bright CD20+ and bright kappa (or lambda)
>positive, while CLL shows dim/weak expression for these markers.
>
>What do some other folks have to say about panels in the workup of chronic
>lymphoid leukemias? (Randy Gascoyne? Curt Hanson?)
>
>***************************************************************
>Christopher R. Conley, MD conley.christopher@mayo.edu
>Dept. of Pathology Tel:(602)301-8021 FAX:(602)301-8372
>Mayo Clinic Scottsdale 13400 E. Shea Blvd. Scottsdale AZ 85259
Maryalice Stetler-Stevenson
Director Flow Cytometry Unit
Laboratory of Pathology, NCI, NIH
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