We have seen a rare example of a T cell malignancy expressing CD20. In
particular, one well documented case of mycosis fungoides demonstrated CD20
expression in addition to the typical CD3+, CD4+, CD7- immunophenotype on a
marrow aspirate. This was confirmed by immunocytochemistry on the biopsy.
Other rare cases have been reported in the literature. As expected, it is
best not to rely on a single immunophenotypic marker to define the lineage of
a neoplastic cell.
Brent Wood MD PhD
Univeristy of Washington
Hematopathology Laboratory