Monoclonal antibody against CD20 (rituximab) is used to treat patients with B-cell malignant lymphomas that express CD20. Sometimes a patient treated with lymphoma will develop a recurrence of lymphoma with CD20-negative cells.
Features:
(1) history of B-cell malignant lymphoma that expresses CD20
(2) prolonged therapy with rituximab
(3) development of a malignant lymphoma that is CD20 negative
Possible explanations
(1) reversible suppression of CD20 expression
(2) selection of CD20-negative clone of same tumor (possibly through deletion of the CD20 gene)
(3) progression to a more aggressive form of lymphoma that is CD20 negative
New Lymphoma
Change After Stopping Rituximab
Diagnosis
same as original
lymphocytes become CD20 positive
reversible suppression
same as original
lymphocytes stay CD20 negative
selection of CD20 negative clone
different and higher grade
NA
progression to more aggressive lymphoma
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